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  • 1. Agapitov, Oleksiy
    et al.
    Krasnoselskikh, Vladimir
    Khotyaintsev, Yuri V.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutet för rymdfysik, Uppsalaavdelningen.
    Rolland, Guy
    A statistical study of the propagation characteristics of whistler waves observed by Cluster2011Ingår i: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 38, s. L20103-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    VLF waves play a crucial role in the dynamics of radiation belts, and are responsible for the loss and the acceleration of energetic electrons. Modeling wave-particle interactions requires the best possible knowledge for how wave energy and wave-normal directions are distributed in L-shells and for the magnetic latitudes of different magnetic activity conditions. In this work, we performed a statistical study for VLF emissions using a whistler frequency range for nine years (2001-2009) of Cluster measurements. We utilized data from the STAFF-SA experiment, which spans the frequency range from 8.8 Hz to 3.56 kHz. We show that the wave energy distribution has two maxima around L similar to 4.5 = 6 and L similar to 2, and that wave-normals are directed approximately along the magnetic field in the vicinity of the geomagnetic equator. The distribution changes with magnetic latitude, and so that at latitudes of similar to 30 degrees, wave-normals become nearly perpendicular to the magnetic field. The observed angular distribution is significantly different from Gaussian and the width of the distribution increases with latitude. Since the resonance condition for wave-particle interactions depends on the wave normal orientation, our results indicate that, due to the observed change in the wave-normal direction with latitude, the most efficient particle diffusion due to wave-particle interaction should occur in a limited region surrounding the geomagnetic equator.

  • 2. Aichner, Bernhard
    et al.
    Makhmudov, Zafar
    Rajabov, Iljomjon
    Zhang, Qiong
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi.
    Pausata, Francesco S. R.
    Werner, Martin
    Heinecke, Liv
    Kuessner, Marie L.
    Feakins, Sarah J.
    Sachse, Dirk
    Mischke, Steffen
    Hydroclimate in the Pamirs Was Driven by Changes in Precipitation-Evaporation Seasonality Since the Last Glacial Period2019Ingår i: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 46, nr 23, s. 13972-13983Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The Central Asian Pamir Mountains (Pamirs) are a high-altitude region sensitive to climatic change, with only few paleoclimatic records available. To examine the glacial-interglacial hydrological changes in the region, we analyzed the geochemical parameters of a 31-kyr record from Lake Karakul and performed a set of experiments with climate models to interpret the results. delta D values of terrestrial biomarkers showed insolation-driven trends reflecting major shifts of water vapor sources. For aquatic biomarkers, positive delta D shifts driven by changes in precipitation seasonality were observed at ca. 31-30, 28-26, and 17-14 kyr BP. Multiproxy paleoecological data and modelling results suggest that increased water availability, induced by decreased summer evaporation, triggered higher lake levels during those episodes, possibly synchronous to northern hemispheric rapid climate events. We conclude that seasonal changes in precipitation-evaporation balance significantly influenced the hydrological state of a large waterbody such as Lake Karakul, while annual precipitation amount and inflows remained fairly constant.

  • 3.
    Akbari, H.
    et al.
    Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO 80309 USA.
    Andersson, L.
    Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO 80309 USA.
    Andrews, David J.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutet för rymdfysik, Uppsalaavdelningen.
    Malaspina, D.
    Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO 80309 USA.
    Benna, M.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA.
    Ergun, R.
    Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO 80309 USA.
    In Situ Electron Density From Active Sounding: The Influence of the Spacecraft Wake2019Ingår i: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 46, nr 17-18, s. 10250-10256Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Results obtained in the Martian ionosphere by the Langmuir Probe and Waves instrument aboard the Mars Atmosphere and Volatile EvolutioN Mission spacecraft are presented. The results include ionospheric electron densities determined from the frequency of Langmuir waves. Since the amplitude of thermal Langmuir waves is often below the instrument's detection level, Langmuir Probe and Waves excites these waves by injecting into the plasma a 3.3-V white noise signal. Electric field spectral measurements obtained shortly after the excitation show a resonance line at frequencies slightly below the local plasma frequency. The observed resonance line is interpreted to originate from plasma waves excited in the wake behind the spacecraft. These results reveal an important phenomenon in electron density estimation from stimulated Langmuir waves. The observed phenomenon, not previously reported by earlier missions, may be a common process in active sounding that can affect in situ electron density measurements.

  • 4.
    Aldahan, Ala
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Luft-, vatten- och landskapslära.
    Hedfors, Jim
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Luft-, vatten- och landskapslära.
    Possnert, Göran
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, Tandemlaboratoriet. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Jonfysik.
    Kulan, Abdulhadi
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Luft-, vatten- och landskapslära.
    Berggren, Ann-Marie
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Luft-, vatten- och landskapslära.
    Söderström, C.
    FOI, Swedish Defence Research Agency, Stockholm, Sweden.
    Atmospheric impact on beryllium isotopes as solar activity proxy2008Ingår i: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 35, nr L21812Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Reconstructing solar activity variability beyond the time scale of actual measurements provides invaluable data for modeling of past and future climate change. The 10 Be isotope has been a primary proxy archive of past solar activity and cosmic ray intensity, particularly for the last millennium. There is, however, a lack of direct high-resolution atmospheric time series on 10 Be that enable estimating atmospheric modulation on the production signal. Here we report quasi-weekly data on 10 Be and 7 Be isotopes covering the periods 1983-2000 and 1975-2006 respectively, that show, for the first time, coherent variations reflecting both atmospheric and production effects. Our data indicate intrusion of stratosphere/upper troposphere air masses that can modulate the isotopes production signal, and may induce relative peaks in the natural 10 Be archives (i.e., ice and sediment). The atmospheric impact on the Be-isotopes can disturb the production signals and consequently the estimate of past solar activity magnitude. Citation: Aldahan, A., J. Hedfors, G. Possnert, A. Kulan, A.-M. Berggren, and C. Soderstrom (2008), Atmospheric impact on beryllium isotopes as solar activity proxy, Geophys. Res. Lett., 35, L21812, doi: 10.1029/2008GL035189.

  • 5.
    Aldahan, Ala
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper.
    Persson, S
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, Tandemlaboratoriet.
    Possnert, Göran
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Jonfysik.
    Hou, Xiaolin
    Distribution of I-127 and I-129 in preciptitation at high European latitudes2009Ingår i: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 36, s. L11805-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

     We here present the most extensive data set on the distribution of   I-127 and I-129 in precipitation (rain and snow) covering the period   2000-2006 and European latitudes 55 degrees N-68 degrees N. Our results   indicate a wide variation in the concentrations and fluxes of the two   isotopes associated with generally higher values at near coastal sites   compared to the inland ones. Total wet-related annual deposition of   I-127 and I-129 on Sweden and Denmark is estimated at about 1.2 x 10(9)   g and 60 g respectively. The average annual I-129 wet deposition   accounts for <1% and <0.05% of the total annual gaseous and liquid,   respectively, discharges from the Sellafiled and La Hague Facilities.   The I-127 annual wet deposition represents < 1% of the estimated global   oceanic iodine flux. Air mass trajectories suggest that events of   enhanced I-129 in precipitation are closely related to southwesterly weather fronts from regions of elevated concentrations.

  • 6.
    Aleinov, I
    et al.
    Columbia Univ, Ctr Climate Syst Res, New York, NY 10027 USA;NASA, Goddard Inst Space Studies, New York, NY 10025 USA.
    Way, Michael J.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi. NASA, Goddard Inst Space Studies, New York, NY 10025 USA; GSFC Sellers Exoplanet Environm Collaborat, Greenbelt, MD USA.
    Harman, C.
    NASA, Goddard Inst Space Studies, New York, NY 10025 USA;Columbia Univ, Dept Appl Phys & Appl Math, New York, NY USA.
    Tsigaridis, K.
    Columbia Univ, Ctr Climate Syst Res, New York, NY 10027 USA;NASA, Goddard Inst Space Studies, New York, NY 10025 USA.
    Wolf, E. T.
    Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO 80309 USA.
    Gronoff, G.
    NASA, Sci Directorate, Chem & Dynam Branch, Langley Res Ctr, Hampton, VA USA;SSAI, Hampton, VA USA.
    Modeling a Transient Secondary Paleolunar Atmosphere: 3-D Simulations and Analysis2019Ingår i: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 46, nr 10, s. 5107-5116Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The lunar history of water deposition, loss, and transport postaccretion has become an important consideration in relation to the possibility of a human outpost on the Moon. Very recent work has shown that a secondary primordial atmosphere of up to 10 mbar could have been emplaced similar to 3.5 x 10(9) years ago due to volcanic outgassing from the maria. Using a zero-dimensional chemistry model, we demonstrate the temperature dependence of the resulting major atmospheric components (CO or CO2). We use a three-dimensional general circulation model to test the viability of such an atmosphere and derive its climatological characteristics. Based on these results, we then conjecture on its capability to transport volatiles outgassed from the maria to the permanently shadowed regions at the poles. Our preliminary results demonstrate that atmospheres as low as 1 mbar are viable and that permanent cold trapping of volatiles is only possible at the poles.

  • 7. Alfimov, V
    et al.
    Aldahan, A
    Possnert, G
    Tracing water masses with I-129 in the western Nordic Seas in early spring 20022004Ingår i: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 31, nr 19Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The distribution of I-129 was utilized for labeling water masses in three sections of the western Nordic Seas. An increase of the tracer in Polar Waters of the East Greenland Current was observed between the Fram Strait and 72degreesN section and attributed to either unaccounted Polar Waters and/or recirculation of cold and fresh Atlantic Waters from the West Spitzbergen Current. Recent convection homogenized I-129 in upper 1000 m of the Greenland Sea, and similar concentrations were observed in dense waters of the Denmark Strait. The densest outflow waters were not found in either the Greenland Sea or the East Greenland Current at 72degreesN.

  • 8. Alm, L.
    et al.
    André, M.
    Vaivads, Andris
    Khotyaintsev, Y. V.
    Torbert, R. B.
    Burch, J. L.
    Ergun, R. E.
    Lindqvist, Per-Arne
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Rymd- och plasmafysik.
    Russell, C. T.
    Giles, B. L.
    Mauk, B. H.
    Magnetotail Hall Physics in the Presence of Cold Ions2018Ingår i: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 45, nr 20, s. 10,941-10,950Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present the first in situ observation of cold ionospheric ions modifying the Hall physics of magnetotail reconnection. While in the tail lobe, Magnetospheric Multiscale mission observed cold (tens of eV) E × B drifting ions. As Magnetospheric Multiscale mission crossed the separatrix of a reconnection exhaust, both cold lobe ions and hot (keV) ions were observed. During the closest approach of the neutral sheet, the cold ions accounted for ∼30% of the total ion density. Approximately 65% of the initial cold ions remained cold enough to stay magnetized. The Hall electric field was mainly supported by the j × B term of the generalized Ohm's law, with significant contributions from the ∇·P e and v c ×B terms. The results show that cold ions can play an important role in modifying the Hall physics of magnetic reconnection even well inside the plasma sheet. This indicates that modeling magnetic reconnection may benefit from including multiscale Hall physics.

  • 9.
    Alm, Love
    et al.
    Swedish Inst Space Phys, Uppsala, Sweden..
    Andre, Mats
    Swedish Inst Space Phys, Uppsala, Sweden..
    Graham, Daniel B.
    Swedish Inst Space Phys, Uppsala, Sweden..
    Khotvaintsev, Yuri, V
    Swedish Inst Space Phys, Uppsala, Sweden..
    Vaivads, Andris
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Rymd- och plasmafysik.
    Chappell, Charles R.
    Vanderbilt Univ, Dept Phys & Astron, Vanderbilt Dyer Observ, Nashville, TN 37235 USA..
    Dargent, Jeremy
    Univ Pisa, Phys Dept Enrico Fermi, Pisa, Italy..
    Fuselier, Stephen A.
    Southwest Res Inst, San Antonio, TX USA.;Univ Texas San Antonio, Dept Phys & Astron, San Antonio, TX USA..
    Haaland, Stein
    Max Planck Inst Solar Syst Res, Gottingen, Germany.;Univ Bergen, Birkeland Ctr Space Sci, Bergen, Norway..
    Lavraud, Benoit
    Univ Toulouse, Inst Rech Astrophys & Planetol, CNRS, UPS,CNES, Toulouse, France..
    Li, Wenya
    Chinese Acad Sci, Natl Space Sci Ctr, State Key Lab Space Weather, Beijing, Peoples R China..
    Tenfjord, Paul
    Univ Bergen, Birkeland Ctr Space Sci, Bergen, Norway..
    Toledo-Redondo, Sergio
    Univ Toulouse, Inst Rech Astrophys & Planetol, CNRS, UPS,CNES, Toulouse, France..
    Vines, Sarah K.
    Johns Hopkins Univ, Appl Phys Lab, Laurel, MD USA..
    MMS Observations of Multiscale Hall Physics in the Magnetotail2019Ingår i: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present Magnetospheric Multiscale mission (MMS) observations of Hall physics in the magnetotail, which compared to dayside Hall physics is a relatively unexplored topic. The plasma consists of electrons, moderately cold ions (T similar to 1.5 keV) and hot ions (T similar to 20 keV). MMS can differentiate between the cold ion demagnetization region and hot ion demagnetization regions, which suggests that MMS was observing multiscale Hall physics. The observed Hall electric field is compared with a generalized Ohm's law, accounting for multiple ion populations. The cold ion population, despite its relatively high initial temperature, has a significant impact on the Hall electric field. These results show that multiscale Hall physics is relevant over a much larger temperature range than previously observed and is relevant for the whole magnetosphere as well as for other astrophysical plasma.

  • 10.
    Alm, Love
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutet för rymdfysik, Uppsalaavdelningen.
    André, Mats
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutet för rymdfysik, Uppsalaavdelningen.
    Graham, Daniel B.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutet för rymdfysik, Uppsalaavdelningen.
    Khotyaintsev, Yuri V.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutet för rymdfysik, Uppsalaavdelningen.
    Vaivads, Andris
    KTH Royal Inst Technol, Stockholm, Sweden.
    Chappell, Charles R.
    Vanderbilt Univ, Dept Phys & Astron, Vanderbilt Dyer Observ, Nashville, TN 37235 USA.
    Dargent, Jeremy
    Univ Pisa, Phys Dept Enrico Fermi, Pisa, Italy.
    Fuselier, Stephen A.
    Southwest Res Inst, San Antonio, TX USA;Univ Texas San Antonio, Dept Phys & Astron, San Antonio, TX USA.
    Haaland, Stein
    Max Planck Inst Solar Syst Res, Gottingen, Germany;Univ Bergen, Birkeland Ctr Space Sci, Bergen, Norway.
    Lavraud, Benoit
    Univ Toulouse, Inst Rech Astrophys & Planetol, CNRS, UPS,CNES, Toulouse, France.
    Li, Wenya
    Chinese Acad Sci, Natl Space Sci Ctr, State Key Lab Space Weather, Beijing, Peoples R China.
    Tenfjord, Paul
    Univ Bergen, Birkeland Ctr Space Sci, Bergen, Norway.
    Toledo-Redondo, Sergio
    Univ Toulouse, Inst Rech Astrophys & Planetol, CNRS, UPS,CNES, Toulouse, France.
    Vines, Sarah K.
    Johns Hopkins Univ, Appl Phys Lab, Laurel, MD USA.
    MMS Observations of Multiscale Hall Physics in the Magnetotail2019Ingår i: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 46, nr 17-18, s. 10230-10239Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present Magnetospheric Multiscale mission (MMS) observations of Hall physics in the magnetotail, which compared to dayside Hall physics is a relatively unexplored topic. The plasma consists of electrons, moderately cold ions (T similar to 1.5 keV) and hot ions (T similar to 20 keV). MMS can differentiate between the cold ion demagnetization region and hot ion demagnetization regions, which suggests that MMS was observing multiscale Hall physics. The observed Hall electric field is compared with a generalized Ohm's law, accounting for multiple ion populations. The cold ion population, despite its relatively high initial temperature, has a significant impact on the Hall electric field. These results show that multiscale Hall physics is relevant over a much larger temperature range than previously observed and is relevant for the whole magnetosphere as well as for other astrophysical plasma.

  • 11.
    Alm, Love
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutet för rymdfysik, Uppsalaavdelningen.
    André, Mats
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutet för rymdfysik, Uppsalaavdelningen.
    Vaivads, Andris
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutet för rymdfysik, Uppsalaavdelningen.
    Khotyaintsev, Yuri V.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutet för rymdfysik, Uppsalaavdelningen.
    Torbert, R. B.
    Univ New Hampshire, Ctr Space Sci, Durham, NH 03824 USA;Southwest Res Inst, San Antonio, TX USA.
    Burch, J. L.
    Southwest Res Inst, San Antonio, TX USA.
    Ergun, R. E.
    Univ Colorado, Atmospher & Space Phys Lab, Campus Box 392, Boulder, CO 80309 USA.
    Lindqvist, P. -A
    Russell, C. T.
    Univ Calif Los Angeles, IGPP EPSS, Los Angeles, CA USA.
    Giles, B. L.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA.
    Mauk, B. H.
    Johns Hopkins Univ, Appl Phys Lab, Laurel, MD USA.
    Magnetotail Hall Physics in the Presence of Cold Ions2018Ingår i: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 45, nr 20, s. 10941-10950Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present the first in situ observation of cold ionospheric ions modifying the Hall physics of magnetotail reconnection. While in the tail lobe, Magnetospheric Multiscale mission observed cold (tens of eV) E x B drifting ions. As Magnetospheric Multiscale mission crossed the separatrix of a reconnection exhaust, both cold lobe ions and hot (keV) ions were observed. During the closest approach of the neutral sheet, the cold ions accounted for similar to 30% of the total ion density. Approximately 65% of the initial cold ions remained cold enough to stay magnetized. The Hall electric field was mainly supported by the j x B term of the generalized Ohm's law, with significant contributions from the del center dot P-e and v(c) x B terms. The results show that cold ions can play an important role in modifying the Hall physics of magnetic reconnection even well inside the plasma sheet. This indicates that modeling magnetic reconnection may benefit from including multiscale Hall physics. Plain Language Summary Cold ions have the potential of changing the fundamental physics behind magnetic reconnection. Here we present the first direct observation of this process in action in the magnetotail. Cold ions from the tail lobes were able to remain cold even deep inside the much hotter plasma sheet. Even though the cold ions only accounted for similar to 30% of the total ions, they had a significant impact on the electric fields near the reconnection region.

  • 12. An, Lu
    et al.
    Rignot, Eric
    Chauche, Nolwenn
    Holland, David M.
    Holland, Denise
    Jakobsson, Martin
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för geologiska vetenskaper.
    Kane, Emily
    Wood, Michael
    Klaucke, Ingo
    Morlighem, Mathieu
    Velicogna, Isabella
    Weinrebe, Wilhelm
    Willis, Josh K.
    Bathymetry of Southeast Greenland From Oceans Melting Greenland (OMG) Data2019Ingår i: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 46, nr 11, s. 197-205Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Southeast Greenland has been a major participant in the ice sheet mass loss over the last several decades. Interpreting the evolution of glacier fronts requires information about their depth below sea level and ocean thermal forcing, which are incompletely known in the region. Here, we combine airborne gravity and multibeam echo sounding data from the National Aeronautics and Space Administration's Oceans Melting Greenland (OMG) mission with ocean probe and fishing boat depth data to reconstruct the bathymetry extending from the glacier margins to the edges of the continental shelf. We perform a three-dimensional inversion of the gravity data over water and merge the solution with a mass conservation reconstruction of bed topography over land. In contrast with other parts of Greenland, we find few deep troughs connecting the glaciers to the sources of warm Atlantic Water, amidst a relatively uniform, shallow (350 m) continental shelf. The deep channels include the Kangerlugssuaq, Sermilik, Gyldenlove, and Tingmiarmiut Troughs.

  • 13. Anderson, L. G.
    et al.
    Jutterstrom, S.
    Hjalmarsson, S.
    Wahlstrom, I.
    Semiletov, I. P.
    Out-gassing of CO2 from Siberian Shelf seas by terrestrial organic matter decomposition2009Ingår i: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 36Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The Siberian shelf seas cover large shallow areas that receive substantial amounts of river discharge. The river runoff contributes nutrients that promote marine primary production, but also dissolved and particulate organic matter. The coastal regions are built up of organic matter in permafrost that thaws and result in coastal erosion and addition of organic matter to the sea. Hence there are multiple sources of organic matter that through microbial decomposition result in high partial pressures of CO2 in the shelf seas. By evaluating data collected from the Laptev and East Siberian Seas in the summer of 2008 we compute an excess of DIC equal to 10.10(12) g C that is expected to be outgassed to the atmosphere and suggest that this excess mainly is caused by terrestrial organic matter decomposition. Citation: Anderson, L. G., S. Jutterstrom, S. Hjalmarsson, I. Wahlstrom, and I. P. Semiletov (2009), Out-gassing of CO2 from Siberian Shelf seas by terrestrial organic matter decomposition, Geophys. Res. Lett., 36, L20601, doi:10.1029/2009GL040046.

  • 14.
    Andersson, Andreas
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för ekoteknik och hållbart byggande. Uppsala University, Uppsala.
    Falck, E.
    Univ Ctr Svalbard, Dept Arctic Geophys, Longyearbyen, Norway.
    Sjöblom, A.
    Uppsala Univ, Dept Earth Sci, Uppsala; Univ Ctr Svalbard, Longyearbyen, Norway.
    Kljun, N.
    Swansea Univ, Swansea, Wales.
    Sahlee, E.
    Uppsala Univ, Uppsala.
    Omar, A. M.
    Bjerknes Ctr Climate Res, Bergen, Norway.
    Rutgersson, A.
    Uppsala Univ, Uppsala.
    Air-sea gas transfer in high Arctic fjords2017Ingår i: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 44, nr 5, s. 2519-2526Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In Arctic fjords and high-latitude seas, strong surface cooling dominates during a large part of the year, generating water-side convection (w(*w)) and enhanced turbulence in the water. These regions are key areas for the global carbon cycle; thus, a correct description of their air-sea gas exchange is crucial. CO2 data were measured via the eddy covariance technique in marine Arctic conditions and reveal that water-side convection has a major impact on the gas transfer velocity. This is observed even at wind speeds as high as 9ms(-1), where convective motions are generally thought to be suppressed by wind-driven turbulence. The enhanced air-sea transfer of CO2 caused by water-side convection nearly doubled the CO2 uptake; after scaled to open-sea conditions the contribution from w(*w) to the CO2 flux remained as high as 34%. This phenomenon is expected to be highly important for the total carbon uptake in marine Arctic areas.

  • 15.
    Andersson, Andreas
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Luft-, vatten- och landskapslära. Department of Ecotechnology and Sustainable Building Engineering, Mid Sweden University, Östersund, Sweden.
    Falck, Eva
    Sjöblom, Anna
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Luft-, vatten- och landskapslära. Department of Arctic Geophysics, University Centre in Svalbard, Longyearbyen, Norway.
    Kljun, Natascha
    Sahlée, Erik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Luft-, vatten- och landskapslära.
    Omar, Abdirahaman
    Rutgersson, Anna
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Luft-, vatten- och landskapslära.
    Air-sea gas transfer in high Arctic fjords2017Ingår i: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 44, nr 5, s. 2519-2526Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In Arctic fjords and high-latitude seas, strong surface cooling dominates during a large part of the year, generating water-side convection (w*w) and enhanced turbulence in the water. These regions are key areas for the global carbon cycle; thus, a correct description of their air-sea gas exchange is crucial. CO2-data were measured via the eddy covariance technique in marine Arctic conditions and reveal that water-side convection has a major impact on the gas transfer velocity. This is observed even at wind speeds as high as 9 m s-1, where convective motions are generally thought to be suppressed by wind-driven turbulence. The enhanced air-sea transfer of CO2 caused by water-side convection nearly doubled the CO2uptake, after scaled to open sea conditions the contribution from  to the CO2 flux remained as high as 34%; this phenomenon is expected to be highly important for the total carbon uptake in marine Arctic areas.

  • 16. Andre, M.
    et al.
    Li, W.
    Toledo-Redondo, S.
    Khotyaintsev, Yu. V.
    Vaivads, Andris
    Graham, D. B.
    Norgren, C.
    Burch, J.
    Lindqvist, Per-Arne
    KTH, Skolan för elektro- och systemteknik (EES), Rymd- och plasmafysik.
    Marklund, Göran
    KTH, Skolan för elektro- och systemteknik (EES), Rymd- och plasmafysik.
    Ergun, R.
    Torbert, R.
    Magnes, W.
    Russell, C. T.
    Giles, B.
    Moore, T. E.
    Chandler, M. O.
    Pollock, C.
    Young, D. T.
    Avanov, L. A.
    Dorelli, J. C.
    Gershman, D. J.
    Paterson, W. R.
    Lavraud, B.
    Saito, Y.
    Magnetic reconnection and modification of the Hall physics due to cold ions at the magnetopause2016Ingår i: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 43, nr 13, s. 6705-6712Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Observations by the four Magnetospheric Multiscale spacecraft are used to investigate the Hall physics of a magnetopause magnetic reconnection separatrix layer. Inside this layer of currents and strong normal electric fields, cold (eV) ions of ionospheric origin can remain frozen-in together with the electrons. The cold ions reduce the Hall current. Using a generalized Ohm's law, the electric field is balanced by the sum of the terms corresponding to the Hall current, the vxB drifting cold ions, and the divergence of the electron pressure tensor. A mixture of hot and cold ions is common at the subsolar magnetopause. A mixture of length scales caused by a mixture of ion temperatures has significant effects on the Hall physics of magnetic reconnection.

  • 17.
    Andrews, David J.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutet för rymdfysik, Uppsalaavdelningen.
    Andersson, L.
    Lab Atmospher & Space Phys, Boulder, CO USA..
    Delory, G. T.
    Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA..
    Ergun, R. E.
    Lab Atmospher & Space Phys, Boulder, CO USA..
    Eriksson, Anders I.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutet för rymdfysik, Uppsalaavdelningen.
    Fowler, C. M.
    Lab Atmospher & Space Phys, Boulder, CO USA..
    McEnulty, T.
    Lab Atmospher & Space Phys, Boulder, CO USA..
    Morooka, M. W.
    Lab Atmospher & Space Phys, Boulder, CO USA..
    Weber, T.
    Lab Atmospher & Space Phys, Boulder, CO USA..
    Jakosky, B. M.
    Lab Atmospher & Space Phys, Boulder, CO USA..
    Ionospheric plasma density variations observed at Mars by MAVEN/LPW2015Ingår i: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 42, nr 21, s. 8862-8869Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We report on initial observations made by the Langmuir Probe and Waves relaxation sounding experiment on board the NASA Mars Atmosphere and Volatile EvolutioN (MAVEN) mission. These measurements yield the ionospheric thermal plasma density, and we use these data here for an initial survey of its variability. Studying orbit-to-orbit variations, we show that the relative variability of the ionospheric plasma density is lowest at low altitudes near the photochemical peak, steadily increases toward higher altitudes and sharply increases as the spacecraft crosses the terminator and moves into the nightside. Finally, despite the small volume of data currently available, we show that a clear signature of the influence of crustal magnetic fields on the thermal plasma density fluctuations is visible. Such results are consistent with previously reported remote measurements made at higher altitudes, but crucially, here we sample a new span of altitudes between similar to 130 and similar to 300 km using in situ techniques.

  • 18.
    Andriopoulou, M.
    et al.
    Austrian Acad Sci, Space Res Inst, A-8010 Graz, Austria..
    Nakamura, R.
    Austrian Acad Sci, Space Res Inst, A-8010 Graz, Austria..
    Torkar, K.
    Austrian Acad Sci, Space Res Inst, A-8010 Graz, Austria..
    Baumjohann, W.
    Austrian Acad Sci, Space Res Inst, A-8010 Graz, Austria..
    Torbert, R. B.
    Univ New Hampshire, Inst Study Earth Oceans & Space, Durham, NH 03824 USA..
    Lindqvist, P. -A
    Khotyaintsev, Yuri V.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutet för rymdfysik, Uppsalaavdelningen.
    Dorelli, J.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Burch, J. L.
    SW Res Inst, San Antonio, TX USA..
    Russell, C. T.
    Univ Calif Los Angeles, Dept Earth Planetary & Space Sci, Los Angeles, CA USA..
    Study of the spacecraft potential under active control and plasma density estimates during the MMS commissioning phase2016Ingår i: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 43, nr 10, s. 4858-4864Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Each spacecraft of the recently launched magnetospheric multiscale MMS mission is equipped with Active Spacecraft Potential Control (ASPOC) instruments, which control the spacecraft potential in order to reduce spacecraft charging effects. ASPOC typically reduces the spacecraft potential to a few volts. On several occasions during the commissioning phase of the mission, the ASPOC instruments were operating only on one spacecraft at a time. Taking advantage of such intervals, we derive photoelectron curves and also perform reconstructions of the uncontrolled spacecraft potential for the spacecraft with active control and estimate the electron plasma density during those periods. We also establish the criteria under which our methods can be applied.

  • 19. Andriopoulou, M.
    et al.
    Nakamura, R.
    Torkar, K.
    Baumjohann, W.
    Torbert, R. B.
    Lindqvist, Per-Arne
    KTH, Skolan för elektro- och systemteknik (EES), Rymd- och plasmafysik.
    Khotyaintsev, Y. V.
    Dorelli, J.
    Burch, J. L.
    Russell, C. T.
    Study of the spacecraft potential under active control and plasma density estimates during the MMS commissioning phase2016Ingår i: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 43, nr 10, s. 4858-4864Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Each spacecraft of the recently launched magnetospheric multiscale MMS mission is equipped with Active Spacecraft Potential Control (ASPOC) instruments, which control the spacecraft potential in order to reduce spacecraft charging effects. ASPOC typically reduces the spacecraft potential to a few volts. On several occasions during the commissioning phase of the mission, the ASPOC instruments were operating only on one spacecraft at a time. Taking advantage of such intervals, we derive photoelectron curves and also perform reconstructions of the uncontrolled spacecraft potential for the spacecraft with active control and estimate the electron plasma density during those periods. We also establish the criteria under which our methods can be applied.

  • 20.
    André, Mats
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutet för rymdfysik, Uppsalaavdelningen.
    Cully, Christopher M.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutet för rymdfysik, Uppsalaavdelningen.
    Low-energy ions: A previously hidden solar system particle population2012Ingår i: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 39, s. L03101-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Ions with energies less than tens of eV originate from the Terrestrial ionosphere and from several planets and moons in the solar system. The low energy indicates the origin of the plasma but also severely complicates detection of the positive ions onboard sunlit spacecraft at higher altitudes, which often become positively charged to several tens of Volts. We discuss some methods to observe low-energy ions, including a recently developed technique based on the detection of the wake behind a charged spacecraft in a supersonic flow. Recent results from this technique show that low-energy ions typically dominate the density in large regions of the Terrestrial magnetosphere on the nightside and in the polar regions. These ions also often dominate in the dayside magnetosphere, and can change the dynamics of processes like magnetic reconnection. The loss of this low-energy plasma to the solar wind is one of the primary pathways for atmospheric escape from planets in our solar system. We combine several observations to estimate how common low-energy ions are in the Terrestrial magnetosphere and briefly compare with Mars, Venus and Titan.

  • 21.
    André, Mats
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutet för rymdfysik, Uppsalaavdelningen.
    Li, Wenya
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutet för rymdfysik, Uppsalaavdelningen.
    Toledo-Redondo, S.
    European Space Agcy ESAC, Madrid, Spain..
    Khotyaintsev, Yuri V.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutet för rymdfysik, Uppsalaavdelningen.
    Vaivads, Andris
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutet för rymdfysik, Uppsalaavdelningen.
    Graham, Daniel B.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutet för rymdfysik, Uppsalaavdelningen.
    Norgren, Cecilia
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutet för rymdfysik, Uppsalaavdelningen. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Rymd- och plasmafysik.
    Burch, J.
    Southwest Res Inst, San Antonio, TX USA..
    Lindqvist, P. -A
    KTH, Stockholm, Sweden.
    Marklund, G.
    KTH, Stockholm, Sweden..
    Ergun, R.
    Univ Colorado, LASP, Boulder, CO 80309 USA..
    Torbert, R.
    Southwest Res Inst, San Antonio, TX USA.;Univ New Hampshire, Durham, NH 03824 USA..
    Magnes, W.
    Austrian Acad Sci, Space Res Inst, Graz, Austria..
    Russell, C. T.
    Univ Calif Los Angeles, Dept Earth & Space Sci, Los Angeles, CA 90024 USA..
    Giles, B.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Moore, T. E.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Chandler, M. O.
    NASA, Marshall Space Flight Ctr, Huntsville, AL USA..
    Pollock, C.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Young, D. T.
    Southwest Res Inst, San Antonio, TX USA..
    Avanov, L. A.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Dorelli, J. C.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Gershman, D. J.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA.;Univ Maryland, Dept Astron, College Pk, MD 20742 USA..
    Paterson, W. R.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Lavraud, B.
    Univ Toulouse, Inst Rech Astrophys & Planetol, Toulouse, France.;CNRS, UMR 5277, Toulouse, France..
    Saito, Y.
    Inst Space & Astronaut Sci, JAXA, Chofu, Tokyo, Japan..
    Magnetic reconnection and modification of the Hall physics due to cold ions at the magnetopause2016Ingår i: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 43, nr 13, s. 6705-6712Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Observations by the four Magnetospheric Multiscale spacecraft are used to investigate the Hall physics of a magnetopause magnetic reconnection separatrix layer. Inside this layer of currents and strong normal electric fields, cold (eV) ions of ionospheric origin can remain frozen-in together with the electrons. The cold ions reduce the Hall current. Using a generalized Ohm's law, the electric field is balanced by the sum of the terms corresponding to the Hall current, the vxB drifting cold ions, and the divergence of the electron pressure tensor. A mixture of hot and cold ions is common at the subsolar magnetopause. A mixture of length scales caused by a mixture of ion temperatures has significant effects on the Hall physics of magnetic reconnection.

  • 22.
    André, Mats
    et al.
    Uppsala universitet, Institutionen för astronomi och rymdfysik.
    Vaivads, Andris
    Buchert, Stephan C.
    Fazakerley, A. N.
    Lahiff, A.
    Thin electron-scale layers at the magnetopause2004Ingår i: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 31, s. L03803-Artikel i tidskrift (Refereegranskat)
  • 23.
    André, Mats
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutet för rymdfysik, Uppsalaavdelningen.
    Vaivads, Andris
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutet för rymdfysik, Uppsalaavdelningen.
    Khotyaintsev, Yu V.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutet för rymdfysik, Uppsalaavdelningen.
    Laitinen, Tiera V.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutet för rymdfysik, Uppsalaavdelningen.
    Nilsson, H.
    Stenberg, G.
    Fazakerley, A.
    Trotignon, J. G.
    Magnetic reconnection and cold plasma at the magnetopause2010Ingår i: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 37, nr 22, s. L22108-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We report on detailed observations by the four Cluster spacecraft of magnetic reconnection and a Flux Transfer Event (FTE) at the magnetopause. We detect cold (eV) plasma at the magnetopause with two independent methods. We show that the cold ions can be essential for the electric field normal to the current sheet in the separatrix region at the edge of the FTE and for the associated acceleration of ions from the magnetosphere into the reconnection jet. The cold ions have small enough gyroradii to drift inside the limited separatrix region and the normal electric field can be balanced by this drift, E approximate to -v x B. The separatrix region also includes cold accelerated electrons, as part of the reconnection current circuit.

  • 24.
    André, Mats
    et al.
    Uppsala universitet, Institutet för rymdfysik, Uppsalaavdelningen.
    Vaivads, Andris
    Uppsala universitet, Institutet för rymdfysik, Uppsalaavdelningen.
    Khotyaintsev, Yu V.
    Uppsala universitet, Institutet för rymdfysik, Uppsalaavdelningen.
    Laitinen, Tiera V.
    Uppsala universitet, Institutet för rymdfysik, Uppsalaavdelningen.
    Nilsson, H.
    Stenberg, G.
    Fazakerley, A.
    Trotignon, J. G.
    Magnetic reconnection and cold plasma at the magnetopause2010Ingår i: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 37, nr 22, s. L22108-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We report on detailed observations by the four Cluster spacecraft of magnetic reconnection and a Flux Transfer Event (FTE) at the magnetopause. We detect cold (eV) plasma at the magnetopause with two independent methods. We show that the cold ions can be essential for the electric field normal to the current sheet in the separatrix region at the edge of the FTE and for the associated acceleration of ions from the magnetosphere into the reconnection jet. The cold ions have small enough gyroradii to drift inside the limited separatrix region and the normal electric field can be balanced by this drift, E approximate to -v x B. The separatrix region also includes cold accelerated electrons, as part of the reconnection current circuit.

  • 25.
    Archer, W. E.
    et al.
    Univ Saskatchewan, Dept Phys & Engn Phys, Saskatoon, SK, Canada.
    Gallardo-Lacourt, B.
    Univ Calgary, Dept Phys & Astron, Calgary, AB, Canada.
    Perry, G. W.
    Univ Calgary, Dept Phys & Astron, Calgary, AB, Canada;New Jersey Inst Technol, Ctr Solar Terr Res, Newark, NJ 07102 USA.
    St-Maurice, J. P.
    Univ Saskatchewan, Dept Phys & Engn Phys, Saskatoon, SK, Canada;Univ Western Ontario, Dept Phys & Astron, London, ON, Canada.
    Buchert, Stephan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutet för rymdfysik, Uppsalaavdelningen. Univ Western Ontario, Dept Phys & Astron, London, ON, Canada.
    Donovan, E.
    Univ Calgary, Dept Phys & Astron, Calgary, AB, Canada.
    Steve: The Optical Signature of Intense Subauroral Ion Drifts2019Ingår i: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 46, nr 12, s. 6279-6286Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Little is currently known about the optical phenomenon known as Steve. The first scientific publication on the subject suggests that Steve is associated with an intense subauroral ion drift (SAID). However, additional inquiry is warranted as this suggested relationship as it is based on a single case study. Here we present eight occurrences of Steve with coincident or near-coincident measurements from the European Space Agency's Swarm satellites and show that Steve is consistently associated with SAID. When satellite observations coincident with Steve are compared to that of typical SAID, we find the SAID associated with Steve to have above average peak ion velocities and electron temperatures, as well as extremely low plasma densities.

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  • 26.
    Arndt, Jan Erik
    et al.
    Alfred Wegener Inst Polar & Marine Res, Bremerhaven, Germany..
    Schenke, Hans Werner
    Alfred Wegener Inst Polar & Marine Res, Bremerhaven, Germany..
    Jakobsson, Martin
    Stockholm Univ, Dept Geol Sci, S-10691 Stockholm, Sweden..
    Nitsche, Frank O.
    Columbia Univ, Lamont Doherty Earth Observ, Palisades, NY USA..
    Buys, Gwen
    British Antarctic Survey, Cambridge CB3 0ET, England..
    Goleby, Bruce
    Geosci Australia, Canberra, ACT, Australia..
    Rebesco, Michele
    Ist Nazl Oceanog & Geofis Sperimentale, Sgonico, Italy..
    Bohoyo, Fernando
    Inst Geol & Minero Espana, Madrid, Spain..
    Hong, Jongkuk
    Korean Polar Res Inst, Inchon, South Korea..
    Black, Jenny
    Inst Geol & Nucl Sci, Lower Hutt, New Zealand..
    Greku, Rudolf
    Ukrainian Acad Sci, Inst Geol Sci, Kiev, Ukraine..
    Udintsev, Gleb
    Vemadsky Inst Geochem & Analyt Chem, Moscow, Russia..
    Barrios, Felipe
    Serv Hidrog & Oceanog, Valparaiso, Chile..
    Reynoso-Peralta, Walter
    Serv Hidrog Naval, Buenos Aires, DF, Argentina..
    Taisei, Morishita
    Japan Coast Guard, Hydrog & Oceanog Dept, Tokyo, Japan..
    Wigley, Rochelle
    Univ New Hampshire, Ctr Coastal & Ocean Mapping, Joint Hydrog Ctr, Durham, NH 03824 USA..
    The International Bathymetric Chart of the Southern Ocean (IBCSO) Version 1.0-A new bathymetric compilation covering circum-Antarctic waters2013Ingår i: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 40, nr 12, s. 3111-3117Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The International Bathymetric Chart of the Southern Ocean (IBCSO) Version 1.0 is a new digital bathymetric model (DBM) portraying the seafloor of the circum-Antarctic waters south of 60 degrees S. IBCSO is a regional mapping project of the General Bathymetric Chart of the Oceans (GEBCO). The IBCSO Version 1.0 DBM has been compiled from all available bathymetric data collectively gathered by more than 30 institutions from 15 countries. These data include multibeam and single-beam echo soundings, digitized depths from nautical charts, regional bathymetric gridded compilations, and predicted bathymetry. Specific gridding techniques were applied to compile the DBM from the bathymetric data of different origin, spatial distribution, resolution, and quality. The IBCSO Version 1.0 DBM has a resolution of 500 x 500 m, based on a polar stereographic projection, and is publicly available together with a digital chart for printing from the project website (www.ibcso.org) and at .

  • 27. Arndt, Jan Erik
    et al.
    Schenke, Hans Werner
    Jakobsson, Martin
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för geologiska vetenskaper.
    Nitsche, Frank O.
    Buys, Gwen
    Goleby, Bruce
    Rebesco, Michele
    Bohoyo, Fernando
    Hong, Jongkuk
    Black, Jenny
    Greku, Rudolf
    Udintsev, Gleb
    Barrios, Felipe
    Reynoso-Peralta, Walter
    Taisei, Morishita
    Wigley, Rochelle
    The International Bathymetric Chart of the Southern Ocean (IBCSO) Version 1.0-A new bathymetric compilation covering circum-Antarctic waters2013Ingår i: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 40, nr 12, s. 3111-3117Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The International Bathymetric Chart of the Southern Ocean (IBCSO) Version 1.0 is a new digital bathymetric model (DBM) portraying the seafloor of the circum-Antarctic waters south of 60 degrees S. IBCSO is a regional mapping project of the General Bathymetric Chart of the Oceans (GEBCO). The IBCSO Version 1.0 DBM has been compiled from all available bathymetric data collectively gathered by more than 30 institutions from 15 countries. These data include multibeam and single-beam echo soundings, digitized depths from nautical charts, regional bathymetric gridded compilations, and predicted bathymetry. Specific gridding techniques were applied to compile the DBM from the bathymetric data of different origin, spatial distribution, resolution, and quality. The IBCSO Version 1.0 DBM has a resolution of 500 x 500 m, based on a polar stereographic projection, and is publicly available together with a digital chart for printing from the project website (www.ibcso.org) and at .

  • 28.
    Artemyev, A. V.
    et al.
    Univ Calif Los Angeles, Dept Earth Planetary & Space Sci, Los Angeles, CA 90095 USA.;Univ Calif Los Angeles, Inst Geophys & Planetary Phys, Los Angeles, CA 90024 USA.;RAS, Space Res Inst, Moscow, Russia..
    Pritchett, P. L.
    Univ Calif Los Angeles, Dept Phys & Astron, Los Angeles, CA 90024 USA..
    Angelopoulos, V.
    Univ Calif Los Angeles, Dept Earth Planetary & Space Sci, Los Angeles, CA 90095 USA.;Univ Calif Los Angeles, Inst Geophys & Planetary Phys, Los Angeles, CA 90024 USA..
    Zhang, X. -J
    Nakamura, R.
    Austrian Acad Sci, Space Res Inst, Graz, Austria..
    Lu, S.
    Univ Calif Los Angeles, Dept Earth Planetary & Space Sci, Los Angeles, CA 90095 USA.;Univ Calif Los Angeles, Inst Geophys & Planetary Phys, Los Angeles, CA 90024 USA..
    Runov, A.
    Univ Calif Los Angeles, Dept Earth Planetary & Space Sci, Los Angeles, CA 90095 USA.;Univ Calif Los Angeles, Inst Geophys & Planetary Phys, Los Angeles, CA 90024 USA..
    Fuselier, S. A.
    Southwest Res Inst, San Antonio, TX USA..
    Wellenzohn, S.
    Austrian Acad Sci, Space Res Inst, Graz, Austria..
    Plaschke, F.
    Austrian Acad Sci, Space Res Inst, Graz, Austria..
    Russell, C. T.
    Univ Calif Los Angeles, Dept Earth Planetary & Space Sci, Los Angeles, CA 90095 USA.;Univ Calif Los Angeles, Inst Geophys & Planetary Phys, Los Angeles, CA 90024 USA..
    Strangeway, R. J.
    Univ Calif Los Angeles, Dept Earth Planetary & Space Sci, Los Angeles, CA 90095 USA.;Univ Calif Los Angeles, Inst Geophys & Planetary Phys, Los Angeles, CA 90024 USA..
    Lindqvist, Per-Arne
    KTH.
    Ergun, R. E.
    Univ Colorado, LASP, Boulder, CO 80309 USA..
    Field-Aligned Currents Originating From the Magnetic Reconnection Region: Conjugate MMS-ARTEMIS Observations2018Ingår i: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 45, nr 12, s. 5836-5844Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Near-Earth magnetic reconnection reconfigures the magnetotail and produces strong plasma flows that transport plasma sheet particles and electromagnetic energy to the inner magnetosphere. An essential element of such a reconfiguration is strong, transient field-aligned currents. These currents, believed to be generated within the plasma sheet and closed at the ionosphere, are responsible for magnetosphere-ionosphere coupling during substorms. We use conjugate measurements from Magnetospheric Multiscale (MMS) at the plasma sheet boundary (around x approximate to- 10R(E)) and Acceleration, Reconnection, Turbulence and Electrodynamics of the Moon's Interaction with the Sun (ARTEMIS) at the equator (around x approximate to- 60R(E)) to explore the potential generation region of these currents. We find a clear correlation between the field-aligned current intensity measured by MMS and the tailward plasma sheet flows measured by ARTEMIS. To better understand the origin of this correlation, we compare spacecraft observations with results from 3-D particle-in-cell simulations of magnetotail reconnection. The comparison reveals that field-aligned currents and plasma flows start, wax, and wane due to the development of a reconnection region between MMS (near-Earth) and ARTEMIS (at lunar distance). A weak correlation between the field-aligned current intensity at MMS and earthward flow magnitudes at ARTEMIS suggests that distant magnetotail reconnection does not significantly contribute to the generation of the observed near-Earth currents. Our findings support the idea that the dominant role of the near-Earth magnetotail reconnection in the field-aligned current generation is likely responsible for their transient nature, whereas more steady distant tail reconnection would support long-term field-aligned current system. Plain Language Summary Field-aligned currents connect the Earth magnetotail and ionosphere, proving energy and information transport from the region where main energy release process, magnetic reconnection, occurs to the region where the collisional energy dissipation takes place. Therefore, investigation and modeling of the field-aligned current generation is important problem of the magnetosphere plasma physics. However, field-aligned current investigation requires simultaneous observations of reconnection signatures in the magnetotail and at high latitudes. Simultaneous and conjugate operation of two multispacecraft missions, Magnetospheric Multiscale and Acceleration, Reconnection, Turbulence and Electrodynamics of the Moon's Interaction with the Sun, for the first time provide an opportunity for such investigation. Combining spacecraft observations with results from 3-D particle-in-cell simulations of magnetotail reconnection, we demonstrate that field-aligned currents and plasma flows start, wax, and wane due to the development of a reconnection region between near-Earth (Magnetospheric Multiscale location) and lunar distant tail (Acceleration, Reconnection, Turbulence and Electrodynamics of the Moon's Interaction with the Sun location). Our findings support the idea that the dominant role of the near-Earth magnetotail reconnection in the field-aligned current generation is likely responsible for their transient nature, whereas more steady distant tail reconnection would support long-term field-aligned current system.

  • 29. Askebjer, P.
    et al.
    Barwick, S. W.
    Bergström, L.
    Bouchta, A.
    Carius, Staffan
    Department of Radiation Sciences, Uppsala University.
    Dalberg, E.
    Erlandsson, B.
    Goobar, A.
    Gray, L.
    Hallgren, A.
    Halzen, F.
    Heukenkamp, H.
    Hulth, P. O.
    Hundertmark, S.
    Jacobsen, J.
    Kandhadai, V.
    Karle, A.
    Liubarsky, I.
    Lowder, D.
    Miller, T.
    Mock, P.
    Morse, R.
    Porrata, R.
    Price, P. B.
    Richards, A.
    Rubinstein, H.
    Schneider, E.
    Spiering, Ch.
    Streicher, O.
    Sun, Q.
    Thon, Th.
    Tilav, S.
    Wischnewski, R.
    Walck, C.
    Yodh, G.
    UV and optical light transmission properties in deep ice at the South Pole1997Ingår i: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 24, nr 11, s. 1355-1358Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Both absorption and scattering of light at wavelengths 410 to 610 nanometers were measured in the South Pole ice at depths 0.8 to 1 kilometer with the laser calibration system of the Antarctic Muon And Neutrino Detector Array (AMANDA). At the shortest wavelengths the absorption lengths exceeded 200 meters - an order of magnitude longer than has been reported for laboratory ice. The absorption shows a strong wavelength dependence while the scattering length is found to be independent of the wavelength, consistent with the hypothesis of a residual density of air bubbles in the ice. The observed linear decrease of the inverse scattering length with depth is compatible with an earlier measurement by the AMANDA collaboration (at ∼515 nanometers).

  • 30.
    Backrud, Marie
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för astronomi och rymdfysik.
    Tjulin, Anders
    Vaivads, Andris
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutet för rymdfysik, Uppsalaavdelningen.
    André, Mats
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för astronomi och rymdfysik.
    Fazakerley, Andrew
    Interferometric Identification of Ion Acoustic Broadband Waves in the Auroral Region: CLUSTER Observations2005Ingår i: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 32, nr 21Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    [1] We determine the phase velocity and k vector for parallel and oblique broadband extremely low frequency, ELF, waves on nightside auroral magnetic field lines at altitudes around 4.6 RE. We use internal burst mode data from the EFW electric field and wave instrument onboard the Cluster spacecraft to retrieve phase differences between the four probes of the instrument. The retrieved characteristic phase velocity is of the order of the ion acoustic speed and larger than the thermal velocity of the protons. The typical wavelength obtained from interferometry is around the proton gyro radius and always larger than the Debye length. We find that in regions with essentially no suprathermal electrons above a few tens of eV the observed broadband waves above the proton gyro frequency are consistent with upgoing ion acoustic and oblique ion acoustic waves.

  • 31.
    Backrud, Marie
    et al.
    Uppsala universitet, Institutionen för astronomi och rymdfysik.
    Tjulin, Anders
    Vaivads, Andris
    Uppsala universitet, Institutet för rymdfysik, Uppsalaavdelningen.
    André, Mats
    Uppsala universitet, Institutionen för astronomi och rymdfysik.
    Fazakerley, Andrew
    Interferometric Identification of Ion Acoustic Broadband Waves in the Auroral Region: CLUSTER Observations2005Ingår i: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 32, nr 21Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    [1] We determine the phase velocity and k vector for parallel and oblique broadband extremely low frequency, ELF, waves on nightside auroral magnetic field lines at altitudes around 4.6 RE. We use internal burst mode data from the EFW electric field and wave instrument onboard the Cluster spacecraft to retrieve phase differences between the four probes of the instrument. The retrieved characteristic phase velocity is of the order of the ion acoustic speed and larger than the thermal velocity of the protons. The typical wavelength obtained from interferometry is around the proton gyro radius and always larger than the Debye length. We find that in regions with essentially no suprathermal electrons above a few tens of eV the observed broadband waves above the proton gyro frequency are consistent with upgoing ion acoustic and oblique ion acoustic waves.

  • 32. Bal, S.
    et al.
    Schimanke, Semjon
    SMHI, Forskningsavdelningen, Oceanografi.
    Spangehl, T.
    Cubasch, U.
    On the robustness of the solar cycle signal in the Pacific region2011Ingår i: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 38, artikel-id L14809Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The potential role of the stratosphere for the 11-year solar cycle signal in the Pacific region is investigated by idealized simulations using a coupled atmosphere-ocean general circulation model. The model includes a detailed representation of the stratosphere and accounts for changes in stratospheric heating rates from prescribed time dependent variations of ozone and spectrally high resolved solar irradiance. Three transient simulations are performed spanning 21 solar cycles each. The simulations use slightly different ozone perturbations representing uncertainties of solar induced ozone variations. The model reproduces the main features of the 20th century observed solar response. A persistent mean sea level pressure response to solar forcing is found for the eastern North Pacific extending over North America. Moreover, there is evidence for a La Nina-like response assigned to solar maximum conditions with below normal SSTs in the equatorial eastern Pacific, reduced equatorial precipitation, enhanced off-equatorial precipitation and an El Nino-like response a couple of years later, thus confirming the response to solar forcing at the surface seen in earlier studies. The amplitude of the solar signal in the Pacific region depends to a great extent on the choice of the centennial period averaged. Citation: Bal, S., S. Schimanke, T. Spangehl, and U. Cubasch (2011), On the robustness of the solar cycle signal in the Pacific region, Geophys. Res. Lett., 38, L14809, doi:10.1029/2011GL047964.

  • 33. Balke, Thorsten
    et al.
    Nilsson, Christer
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap. Department of Wildlife, Fish and Environmental Studies, Swedish University of Agricultural Sciences, Umeå, Sweden.
    Increasing Synchrony of Annual River‐Flood Peaks and Growing Season in Europe2019Ingår i: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 46, nr 17-18, s. 10446-10453Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In a changing climate, time sensitive ecological interactions such as pollination and predation are vulnerable to temporal mismatch with direct consequences for ecosystem functioning. It is not known if synchrony and asynchrony of ecological and physical processes such as flood disturbance and plant phenology may similarly be affected by climate change. Here, by spatially merging temperature and flood peak data, we show for the first time that in Central and Eastern Europe, annual river flood peaks increasingly occur within the thermal growing season. This is due to the combined effect of earlier spring onsets and later flood peaks. Such increased physical‐phenological synchrony may especially impact river biogeomorphology and riparian floodplain ecosystem functioning through uprooting of seedlings and increased hydraulic roughness during major flood events.

  • 34. Ball, W. T.
    et al.
    Rozanov, E.
    Alsing, J.
    Marsh, D. R.
    Tummon, F.
    Mortlock, Daniel J.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Imperial College London, UK.
    Kinnison, D.
    Haigh, J. D.
    The Upper Stratospheric Solar Cycle Ozone Response2019Ingår i: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 46, nr 3, s. 1831-1841Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The solar cycle (SC) stratospheric ozone response is thought to influence surface weather and climate. To understand the chain of processes and ensure climate models adequately represent them, it is important to detect and quantify an accurate SC ozone response from observations. Chemistry climate models (CCMs) and observations display a range of upper stratosphere (1-10 hPa) zonally averaged spatial responses; this and the recommended data set for comparison remains disputed. Recent data-merging advancements have led to more robust observational data. Using these data, we show that the observed SC signal exhibits an upper stratosphere U-shaped spatial structure with lobes emanating from the tropics (5-10 hPa) to high altitudes at midlatitudes (1-3 hPa). We confirm this using two independent chemistry climate models in specified dynamics mode and an idealized timeslice experiment. We recommend the BASIC(v2) ozone composite to best represent historical upper stratospheric solar variability, and that those based on SBUV alone should not be used. Plain Language Summary Changes in the output of the Sun are thought to influence surface weather and climate through a set of processes initiated by the enhancement of upper stratosphere (32-48 km) ozone. In order to understand and assess the solar impact on the climate system, it is important that models reproduce the observed solar signal. However, the recommended data set for comparison with climate models remains disputed. We use newly improved observed ozone composites to determine both why there is disagreement between composites and which is most likely to be correct. We find that artifact-corrected composites represent the response better than those based on SBUV data alone. Further, we identify a U-shaped spatial structure with lobes emanating from the tropics to high altitudes at midlatitudes. An idealized chemistry climate model experiment and simulations considering historical meteorological conditions both support this conclusion. The results are of benefit to satellite-instrument scientists and to those engaged in atmospheric and climate research using both observations and climate models. The results will be important for assessing the solar signal in currently active and future assessments of chemistry climate models (e.g., Chemistry-Climate Model Initiative). We recommend the BASICv2 ozone composite to best represent historical upper stratospheric variability.

  • 35.
    Baltar, Federico
    et al.
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för naturvetenskap, NV.
    Arístegui, Javier
    Sintes, Eva
    Reinthaler, Thomas
    Gasol, Josep M.
    Herndl, Gerhard J.
    Significance of non-sinking particulate organic carbon and dark CO2 fixation to heterotrophic carbon demand in the mesopelagic Atlantic2010Ingår i: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 37, s. L09602-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    It is generally assumed that sinking particulate organic carbon (POC) constitutes the main source of organic carbon supply to the deep ocean's food webs. However, a major discrepancy between the rates of sinking POC supply (collected with sediment traps) and the prokaryotic organic carbon demand (the total amount of carbon required to sustain the heterotrophic metabolism of the prokaryotes; i.e., production plus respiration, PCD) of deep-water communities has been consistently reported for the dark realm of the global ocean. While the amount of sinking POC flux declines exponentially with depth, the concentration of suspended, buoyant non-sinking POC (nsPOC; obtained with oceanographic bottles) exhibits only small variations with depth in the (sub) tropical Northeast Atlantic. Based on available data for the North Atlantic we show here that the sinking POC flux would contribute only 4-12% of the PCD in the mesopelagic realm (depending on the primary production rate in surface waters). The amount of nsPOC potentially available to heterotrophic prokaryotes in the mesopelagic realm can be partly replenished by dark dissolved inorganic carbon fixation contributing between 12% to 72% to the PCD daily. Taken together, there is evidence that the mesopelagic microheterotrophic biota is more dependent on the nsPOC pool than on the sinking POC supply. Hence, the enigmatic major mismatch between the organic carbon demand of the deep-water heterotrophic microbiota and the POC supply rates might be substantially smaller by including the potentially available nsPOC and its autochthonous production in oceanic carbon cycling models. Citation: Baltar, F., J. Aristegui, E. Sintes, J. M. Gasol, T. Reinthaler, and G. J. Herndl (2010), Significance of non-sinking particulate organic carbon and dark CO2 fixation to heterotrophic carbon demand in the mesopelagic northeast Atlantic.

  • 36. Barabash, Victoria
    et al.
    Chilson, P.
    Kirkwood, S.
    Réchou, A.
    Stebel, K.
    Investigations of the possible relationship between PMSE and tides using a VHF MST radar1998Ingår i: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 25, nr 17, s. 3297-3300Artikel i tidskrift (Refereegranskat)
  • 37. Baskaran, M
    Interaction of sea ice sediments and surface sea water in the Arctic Ocean: Evidence from excess Pb-2102005Ingår i: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 32, nr 12Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We measured the activities of Pb-210, Ra-226, U-238 and Cs-137 in a suite of ice-rafted sediments (IRS) from the Arctic Ocean in an attempt to assess the interaction of sea ice sediments and surface water. The concentrations of these nuclides were compared to those of the benthic sediments in the coastal and shelf regions of the Arctic Ocean, which are believed to be the major source region for the IRS. The concentration factors (CF = activity of a nuclide in IRS/average activity in benthic sediments) are similar to 1 and 4-92 for Cs-137 and Pb-210, respectively. The CF values for Cs-137 are comparable to the values that can be obtained from the previously published data while we report the first set of high CF values of Pb-210. A major portion of Pb-210 in some IRS samples is likely derived from surface waters and thus, the concentrations of Pb-210 combined with another particle-reactive radionuclide (such as Be-7, Th-234) in IRS might provide information on the residence time and transit time of sea ice-laden sediments.

  • 38. Basu, N. B.
    et al.
    Destouni, G.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Jawitz, J. W.
    Thompson, S. E.
    Loukinova, N. V.
    Darracq, A.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Zanardo, S.
    Yaeger, M.
    Sivapalan, M.
    Rinaldo, A.
    Rao, P. S. C.
    Nutrient loads exported from managed catchments reveal emergent biogeochemical stationarity2010Ingår i: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 37, nr L23404Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Complexity of heterogeneous catchments poses challenges in predicting biogeochemical responses to human alterations and stochastic hydro‐climatic drivers. Human interferences and climate change may have contributed to the demise of hydrologic stationarity, but our synthesis of a large body of observational data suggests that anthropogenic impacts have also resulted in the emergence of effective biogeochemical stationarity in managed catchments. Long‐term monitoring data from the Mississippi‐Atchafalaya River Basin (MARB) and the Baltic Sea Drainage Basin (BSDB) reveal that inter‐annual variations in loads (LT) for total‐N (TN) and total‐P (TP), exported from a catchment are dominantly controlled by discharge (QT) leading inevitably to temporal invariance of the annual, flow‐weighted concentration, = (LT/QT). Emergence of this consistent pattern across diverse managed catchments is attributed to the anthropogenic legacy of accumulated nutrient sources generating memory, similar to ubiquitously present sources for geogenic constituents that also exhibit a linear LTQT relationship. These responses are characteristic of transport‐limited systems. In contrast, in the absence of legacy sources in less‐managed catchments, values were highly variable and supply limited. We offer a theoretical explanation for the observed patterns at the event scale, and extend it to consider the stochastic nature of rainfall/flow patterns at annual scales. Our analysis suggests that: (1) expected inter‐annual variations in LT can be robustly predicted given discharge variations arising from hydro‐climatic or anthropogenic forcing, and (2) water‐quality problems in receiving inland and coastal waters would persist until the accumulated storages of nutrients have been substantially depleted. The finding has notable implications on catchment management to mitigate adverse water‐quality impacts, and on acceleration of global biogeochemical cycles.

  • 39.
    Becerra Garcia, Marley
    et al.
    Division for Electricity, Uppsala University.
    Cooray, Vernon
    Division for Electricity, Uppsala University.
    On the velocity of positive connecting leaders associated with negative downward lightning leaders2008Ingår i: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 35, nr 2Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A self-consistent leader propagation model is used to estimate the velocity of upward connecting positive leaders initiated from a tall tower under the influence of downward negative lightning leaders. The propagation of upward connecting leaders has been found to be influenced not only by the average velocity of the downward leader but also by the prospective return stroke current, the lateral position of the downward leader channel as well as by the ambient electric field. This result show that the velocity and propagation time of upward connecting positive leaders change from flash to flash due to the variations in these parameters.

  • 40.
    Becerra, Marley
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Cooray, Vernon
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    On the velocity of positive connecting leaders associated with negative downward lightning leaders2008Ingår i: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 35, s. L02801-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A self-consistent leader propagation model is used to estimate the velocity of upward connecting positive leaders initiated from a tall tower under the influence of downward negative lightning leaders. The propagation of upward connecting leaders has been found to be influenced not only by the average velocity of the downward leader but also by the prospective return stroke current, the lateral position of the downward leader channel as well as by the ambient electric field. This result show that the velocity and propagation time of upward connecting positive leaders change from flash to flash due to the variations in these parameters.

  • 41.
    Behar, Etienne
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik.
    Nilsson, Hans
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Rymdteknik.
    Wieser, Gabriella Stenberg
    Swedish Institute of Space Physics.
    Nemeth, Zoltan
    Wigner Research Centre for Physics, 1121 Konkoly Thege Street 29-33, Budapest.
    Brolles, T.W.
    Space Science and Engineering Division, Southwest Research Institute, San Antonio.
    Richter, Ingo
    Technische Universität–Braunschweig, Institute for Geophysics and Extraterrestrial Physics.
    Mass loading at 67P/Churyumov-Gerasimenko: A case study2016Ingår i: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 43, nr 4, s. 1411-1418Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We study the dynamics of the interaction between the solar wind ions and a partially ionized atmosphere around a comet, at a distance of 2.88 AU from the Sun during a period of low nucleus activity. Comparing particle data and magnetic field data for a case study, we highlight the prime role of the solar wind electric field in the cometary ion dynamics. Cometary ion and solar wind proton flow directions evolve in a correlated manner, as expected from the theory of mass loading. We find that the main component of the accelerated cometary ion flow direction is along the antisunward direction and not along the convective electric field direction. This is interpreted as the effect of an antisunward polarization electric field adding up to the solar wind convective electric field.

  • 42.
    Behlke, Rico
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för astronomi och rymdfysik.
    André, Mats
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för astronomi och rymdfysik, Rymdfysik.
    Bale, Stuart D.
    Pickett, Jolene S.
    Cattell, Cynthia A.
    Lucek, Elizabeth A.
    Balogh, Andre
    Solitary structures associated with short large-amplitude magnetic structures (SLAMS) upstream of the Earth's quasi-parallel bow shock2004Ingår i: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 31, nr 16Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    [1] For the first time, solitary waves (SWs) have been observed within short large-amplitude magnetic structures (SLAMS) upstream of the Earth's quasi-parallel bow shock. The SWs often occur as bipolar pulses in the electric field data and move parallel to the background magnetic field at velocities of v = 400–1200 km/s. They have peak-to-peak amplitudes in the parallel electric field of up to E = 65 mV/m and parallel scale sizes of L ∼ 10 λD. The bipolar solitary waves exhibit negative potential structures of ∣Φ∣ = 0.4–2.2 V, i.e., eΦ/kTe ∼ 0.1. None of the theories commonly used to describe SWs adequately address these negative potential structures moving at velocities above the ion thermal speed in a weakly magnetized plasma.

  • 43.
    Behlke, Rico
    et al.
    Uppsala universitet, Institutionen för astronomi och rymdfysik.
    André, Mats
    Buchert, Stephan C.
    Vaivads, Andris
    Eriksson, Anders I.
    Lucek, Elizabeth A.
    Balogh, Andre
    Multi-point electric field measurements of Short Large-Amplitude Magnetic Structures (SLAMS) at the Earth' quasi-parallel bow shock2003Ingår i: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 30, nr 4Artikel i tidskrift (Refereegranskat)
  • 44. Belcher, Stephen E.
    et al.
    Grant, Alan L. M.
    Hanley, Kirsty E.
    Fox-Kemper, Baylor
    Van Roekel, Luke
    Sullivan, Peter P.
    Large, William G.
    Brown, Andy
    Hines, Adrian
    Calvert, Daley
    Rutgersson, Anna
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Luft-, vatten- och landskapslära.
    Pettersson, Heidi
    Bidlot, Jean-Raymond
    Janssen, Peter A. E. M.
    Polton, Jeff A.
    A global perspective on Langmuir turbulence in the ocean surface boundary layer2012Ingår i: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 39, s. L18605-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The turbulent mixing in thin ocean surface boundary layers (OSBL), which occupy the upper 100 m or so of the ocean, control the exchange of heat and trace gases between the atmosphere and ocean. Here we show that current parameterizations of this turbulent mixing lead to systematic and substantial errors in the depth of the OSBL in global climate models, which then leads to biases in sea surface temperature. One reason, we argue, is that current parameterizations are missing key surface-wave processes that force Langmuir turbulence that deepens the OSBL more rapidly than steady wind forcing. Scaling arguments are presented to identify two dimensionless parameters that measure the importance of wave forcing against wind forcing, and against buoyancy forcing. A global perspective on the occurrence of wave-forced turbulence is developed using re-analysis data to compute these parameters globally. The diagnostic study developed here suggests that turbulent energy available for mixing the OSBL is under-estimated without forcing by surface waves. Wave-forcing and hence Langmuir turbulence could be important over wide areas of the ocean and in all seasons in the Southern Ocean. We conclude that surface-wave-forced Langmuir turbulence is an important process in the OSBL that requires parameterization. Citation: Belcher, S. E., et al. (2012), A global perspective on Langmuir turbulence in the ocean surface boundary layer, Geophys. Res. Lett., 39, L18605, doi: 10.1029/2012GL052932.

  • 45.
    Bergbauer, S.
    et al.
    University of Hawaii.
    Martel, S.J.
    University of Hawaii.
    Hieronymus, C.F.
    University of Hawaii.
    Thermal stress evolution in cooling pluton environments of different geometries1998Ingår i: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 25, nr 5, s. 707-71-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Thermoelastic displacement potentials and fast Fourier transforms can be combined to rapidly calculate the thermal stresses in 2-D for plutons that cool by conduction. First, temperature distributions over time are computed by solving the diffusion equation. Thermal stresses are then obtained using thermoelastic stress potentials. This method can be applied to a broad range of pluton geometries and initial conditions, and requires far less computation time than finite difference or finite element analyses. Results of 2-D analyses show that pluton geometry strongly influences the thermal stresses that occur in a cooling pluton. Thermal stresses of several tens of MPa arise during cooling and are highest at the corners or where the intrusion is thin. The most tensile stress is greater inside a pluton than in the host rock. Moreover, the orientation of the most tensile stress in a cooling pluton generally changes over time. This could result in multiple fracture sets, which would significantly affect the mechanical and hydraulic behavior of a pluton.

  • 46. Berggren, A. M.
    et al.
    Beer, J.
    Possnert, G.
    Aldahan, A.
    Kubik, P.
    Christl, M.
    Johnsen, S. J.
    Abreu, J.
    Vinther, B. M.
    A 600-year annual Be-10 record from the NGRIP ice core, Greenland2009Ingår i: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 36, artikel-id L11801Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Despite the extensive use of Be-10 as the most significant information source on past solar activity, there has been only one record (Dye-3, Greenland) providing annual resolution over several centuries. Here we report a new annual resolution Be-10 record spanning the period 1389-1994 AD, measured in an ice core from the NGRIP site in Greenland. NGRIP and Dye-3 Be-10 exhibits similar long-term variability, although occasional short term differences between the two sites indicate that at least two high resolution Be-10 records are needed to assess local variations and to confidently reconstruct past solar activity. A comparison with sunspot and neutron records confirms that ice core Be-10 reflects solar Schwabe cycle variations, and continued Be-10 variability suggests cyclic solar activity throughout the Maunder and Sporer grand solar activity minima. Recent Be-10 values are low; however, they do not indicate unusually high recent solar activity compared to the last 600 years. Citation: Berggren, A.-M., J. Beer, G. Possnert, A. Aldahan, P. Kubik, M. Christl, S. J. Johnsen, J. Abreu, and B. M. Vinther (2009), A 600-year annual Be-10 record from the NGRIP ice core, Greenland, Geophys. Res. Lett., 36, L11801, doi: 10.1029/2009GL038004.

  • 47.
    Berggren, Ann-Marie
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Luft-, vatten- och landskapslära.
    Beer, Juerg
    Possnert, Göran
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Jonfysik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, Tandemlaboratoriet.
    Aldahan, Ala
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Luft-, vatten- och landskapslära.
    Kubik, Peter
    ETH, Zurich, Switzerland.
    Christl, Marcus
    ETH, Zurich, Switzerland.
    Johnsen, Sigfús J.
    Niels Bohr Institute, Copenhagen, Denmark.
    Abreu, José
    Eawag, Zurich, Switzerland.
    Vinter, Bo M.
    Niels Bohr Institute, Copenhagen, Denmark.
    A 600-year annual 10Be record from the NGRIP ice core, Greenland2009Ingår i: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 36, s. L11801-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Despite the extensive use of 10Be as the most significant information source on past solar activity, there has been only one record (Dye-3, Greenland) providing annual resolution over several centuries. Here we report a new annual resolution 10Be record spanning the period 1389-1994 AD, measured in an ice core from the NGRIP site in Greenland. NGRIP and Dye-3 10Be exhibits similar long-term variability, although occasional short term differences between the two sites indicate that at least two high resolution 10Be records are needed to assess local variations and to confidently reconstruct past solar activity. A comparison with sunspot and neutron records confirms that ice core 10Be reflects solar Schwabe cycle variations, and continued 10Be variability suggests cyclic solar activity throughout the Maunder and Spörer grand solar activity minima. Recent 10Be values are low; however, they do not indicate unusually high recent solar activity compared to the last 600 years.

  • 48. Bertucci, C.
    et al.
    Hamilton, D. C.
    Kurth, W. S.
    Hospodarsky, G.
    Mitchell, D.
    Sergis, N.
    Edberg, Niklas J. T.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutet för rymdfysik, Uppsalaavdelningen.
    Dougherty, M. K.
    Titan's interaction with the supersonic solar wind2015Ingår i: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 42, nr 2, s. 193-200Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    After 9years in the Saturn system, the Cassini spacecraft finally observed Titan in the supersonic and super-Alfvenic solar wind. These unique observations reveal that Titan's interaction with the solar wind is in many ways similar to unmagnetized planets Mars and Venus and active comets in spite of the differences in the properties of the solar plasma in the outer solar system. In particular, Cassini detected a collisionless, supercritical bow shock and a well-defined induced magnetosphere filled with mass-loaded interplanetary magnetic field lines, which drape around Titan's ionosphere. Although the flyby altitude may not allow the detection of an ionopause, Cassini reports enhancements of plasma density compatible with plasma clouds or streamers in the flanks of its induced magnetosphere or due to an expansion of the induced magnetosphere. Because of the upstream conditions, these observations may be also relevant to other bodies in the outer solar system such as Pluto, where kinetic processes are expected to dominate.

  • 49. Bertucci, C.
    et al.
    Neubauer, F. M.
    Szego, K.
    Wahlund, Jan Erik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutet för rymdfysik, Uppsalaavdelningen.
    Coates, A. J.
    Dougherty, M. K.
    Young, D. T.
    Kurth, W. S.
    Structure of Titan's mid-range magnetic tail: Cassini magnetometer observations during the T9 flyby2007Ingår i: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 34, nr 24, s. L24S02-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We analyze the magnetic structure of Titan's mid-range magnetic tail (5-6 Titan radii downstream from the moon) during Cassini's T9 flyby. Cassini magnetometer (MAG) measurements reveal a well-defined, induced magnetic tail consisting of two lobes and a distinct central current sheet. MAG observations also indicate that Saturn's background magnetic field is close to the moon's orbital plane and that the magnetospheric flow has a significant component in the Saturn-Titan direction. The analysis of MAG data in a coordinate system based on the orientation of the background magnetic field and an estimation of the incoming flow direction suggests that Titan's magnetic tail is extremely asymmetric. An important source of these asymmetries is the connection of the inbound tail lobe and the outbound tail lobe to the dayside and nightside hemispheres of Titan, respectively. Another source could be the perturbations generated by changes in the upstream conditions.

  • 50. Bjork, G
    et al.
    Soderkvist, J
    Winsor, P
    Nikolopoulos, A
    Steele, M
    Return of the cold halocline layer to the Amundsen Basin of the Arctic Ocean: Implications for the sea ice mass balance2002Ingår i: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 29, nr 11Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    [1] CTD measurements from the Arctic Ocean 2001 expedition reveal that the cold halocline layer (CHL) has returned to the Amundsen Basin at a position close to that found during the Oden’91 expedition. River water from the Siberian shelves formed a strong freshwater front in the Amundsen Basin, extending from the Gakkel Ridge to the Lomonosov Ridge. Furthermore, we show from model computations that the presence of a CHL may increase winter sea ice growth by 0.25 m over one season compared to a case with a non-existing CHL due to increased vertical heat flux from the warm Atlantic water. The difference in sea ice growth is due to a much shallower winter convection with a CHL present, which is not able to reach into the warm Atlantic layer, resulting in a considerably smaller oceanic heat flux.

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