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  • 1.
    Baron, P.
    et al.
    National Institute of Information and Communications Technology, 4-2-1 Nukui-kitamachi, Koganei.
    Urban, J.
    Chalmers University of Technology.
    Sagawa, H.
    National Institute of Information and Communications Technology, 4-2-1 Nukui-kitamachi, Koganei.
    Möller, J.
    Chalmers University of Technology.
    Murtagh, D.P.
    Chalmers University of Technology.
    Mendrok, Jana
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Dupuy, E.
    National Institute of Information and Communications Technology, 4-2-1 Nukui-kitamachi, Koganei.
    Sato, T.O.
    National Institute of Information and Communications Technology, 4-2-1 Nukui-kitamachi, Koganei.
    Ochiai, S.
    National Institute of Information and Communications Technology, 4-2-1 Nukui-kitamachi, Koganei.
    Suzuki, K.
    National Institute of Information and Communications Technology, 4-2-1 Nukui-kitamachi, Koganei.
    Manabe, T.
    Osaka Prefecture University, Naka, Sakai.
    Nishibori, T.
    Japan Aerospace Exploration Agency (JAXA), Tsukuba.
    Kikuchi, K.
    Japan Aerospace Exploration Agency (JAXA), Tsukuba.
    Sato, R.
    Japan Aerospace Exploration Agency (JAXA), Tsukuba.
    Takayanagi, M.
    Japan Aerospace Exploration Agency (JAXA), Tsukuba.
    Murayama, Y.
    National Institute of Information and Communications Technology, 4-2-1 Nukui-kitamachi, Koganei.
    Shiotani, M.
    Research Institute for Sustainable Humanosphere, Kyoto University.
    Kasai, Y.
    National Institute of Information and Communications Technology, 4-2-1 Nukui-kitamachi, Koganei.
    The level 2 research product algorithms for the superconducting submillimeter-wave limb-emission sounder (SMILES)2011In: Atmospheric Measurement Techniques Discussions, ISSN 1867-8610, E-ISSN 1867-8610, Vol. 4, no 3, 3593-3645 p.Article in journal (Refereed)
    Abstract [en]

    This paper describes the algorithms of the level-2 research (L2r) processingchain developed for the Superconducting Submillimeter-Wave Limb-EmissionSounder (SMILES). The chain has been developed in parallel to the operationalchain for conducting researches on calibration and retrieval algorithms. L2rchain products are available to the scientific community. The objective ofversion 2 is the retrieval of the vertical distribution of trace gases in thealtitude range of 18-90 km. An theoretical error analysis is conducted toestimate the retrieval feasibility of key parameters of the processing:line-of-sight elevation tangent altitudes (or angles), temperature and O3 profiles. The line-of-sight tangent altitudes are retrievedbetween 20 and 50 km from the strong ozone (O3) line at 625.371 GHz,with low correlation with the O3 volume-mixing ratio and temperatureretrieved profiles. Neglecting the non-linearity of the radiometric gain inthe calibration procedure is the main systematic error. It is large for theretrieved temperature (between 5-10 K). Therefore, atmospheric pressure cannot be derived from the retrieved temperature, and, then, in the altituderange where the line-of-sight tangent altitudes are retrieved, the retrievedtrace gases profiles are found to be better represented on pressure levelsthan on altitude levels. The error analysis for the retrieved HOCl profiledemonstrates that best results for inverting weak lines can be obtained byusing narrow spectral windows. Future versions of the L2r algorithms willimprove the temperature/pressure retrievals and also provide information inthe upper tropospheric/lower stratospheric region (e.g., water vapor, icecontent, O3) and on stratospheric and mesospheric line-of-sight winds.

  • 2. Kiefer, M.
    et al.
    Arnone, E.
    Dudhia, A.
    Carlotti, M.
    Castelli, E.
    Clarmann, T. von
    Dinelli, B. M.
    Kleinert, A.
    Linden, A.
    Milz, Mathias
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Papandrea, E.
    Stiller, G.
    Impact of temperature field inhomogeneities on the retrieval of atmospheric species from MIPAS IR limb emission spectra2010In: Atmospheric Measurement Techniques Discussions, ISSN 1867-8610, E-ISSN 1867-8610, Vol. 3, no 2, 1707-1742 p.Article in journal (Refereed)
    Abstract [en]

    We examine volume mixing ratios (vmr) retrieved from limb emission spectra recorded with the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS). In level 2 (L2) data products of three different retrieval processors, which perform one dimensional (1-D) retrievals, we find significant differences between species' profiles from ascending and descending orbit parts. The relative differences vary systematically with time of the year, latitude, and altitude. In the lower stratosphere their monthly means can reach maxima of 20% for CFC-11, CFC-12, HNO3, H2O, 10% for CH4 and N2O. Relative differences between monthly means of 1-D retrieval results and of the true atmospheric state can be expected to reach half of these percentage values, while relative differences in single vmr profiles might well exceed those numbers. Often there are no physical or chemical reasons for these differences, so they are an indicator for a problem in the data processing. The differences are generally largest at locations where the meridional temperature gradient of the atmosphere is strong. On the contrary, when performing the retrieval with a tomographic two dimensional (2-D) retrieval, L2 products generally do not show these differences. This implies that inhomogeneities in the temperature field, and possibly in the species' fields, which are accounted for in the 2-D algorithm and not in standard 1-D processors, may cause significant deviations in the results. Inclusion of an externally given adequate temperature gradient in the forward model of a 1-D processor helps to reduce the observed differences. However, only the full tomographic approach is suitable to resolve the horizontal inhomogeneities. Implications for the use of the 1-D data, e.g. for validation, are discussed. The dependence of the ascending/descending differences on the observation strategy suggests that this problem is to be expected to affect in general 1-D retrievals of infrared limb sounders, if the line of sight of the instrument has a significant component in the direction of the horizontal temperature variation.

  • 3.
    Larsson, Richard
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Milz, Mathias
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Rayer, P.
    UK Met Office, Exeter.
    Saunders, R.
    UK Met Office, Exeter.
    Bell, W.
    UK Met Office, Exeter.
    Booton, A.
    UK Met Office, Exeter.
    Buehler, S.A.
    Meteorological Institute, University of Hamburg, Hamburg.
    Eriksson, P.
    Chalmers University of Technology, Department of Earth and Space Sciences.
    John, V.
    EUMETSAT, Darmstadt.
    Modeling the Zeeman effect in high altitude SSMIS channels for numerical weather prediction profiles: Comparing a fast model and a line-by-line model2015In: Atmospheric Measurement Techniques Discussions, ISSN 1867-8610, E-ISSN 1867-8610, Vol. 8, no 10, 10179-10211 p.Article in journal (Refereed)
    Abstract [en]

    We present a comparison of a reference and a fast radiative transfer model using numerical weather prediction profiles for the Zeeman-affected high altitude Special Sensor Microwave Imager/Sounder channels 19–22. We find that the models agree well for channels 21 and 22 compared to the channels' system noise temperatures (1.9 and 1.3 K, respectively) and the expected profile errors at the affected altitudes (estimated to be around 5 K). For channel 22 there is a 0.5 K average difference between the models, with a standard deviation of 0.24 K for the full set of atmospheric profiles. Same channel, there is 1.2 K in average between the fast model and the sensor measurement, with 1.4 K standard deviation. For channel 21 there is a 0.9 K average difference between the models, with a standard deviation of 0.56 K. Same channel, there is 1.3 K in average between the fast model and the sensor measurement, with 2.4 K standard deviation. We consider the relatively small model differences as a validation of the fast Zeeman effect scheme for these channels. Both channels 19 and 20 have smaller average differences between the models (at below 0.2 K) and smaller standard deviations (at below 0.4 K) when both models use a two-dimensional magnetic field profile. However, when the reference model is switched to using a full three-dimensional magnetic field profile, the standard deviation to the fast model is increased to almost 2 K due to viewing geometry dependencies causing up to ± 7 K differences near the equator. The average differences between the two models remain small despite changing magnetic field configurations. We are unable to compare channels 19 and 20 to sensor measurements due to limited altitude range of the numerical weather prediction profiles. We recommended that numerical weather prediction software using the fast model takes the available fast Zeeman scheme into account for data assimilation of the affected sensor channels to better constrain the upper atmospheric temperatures.

  • 4.
    Reinap, Ausra
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Wiman, Bo L. B.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Gunnarsson, Sara
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Svenningsson, Birgitta
    Lund University.
    Dry deposition of NaCl aerosols: theory and method for a modified leaf-washing technique2010In: Atmospheric Measurement Techniques Discussions, ISSN 1867-8610, E-ISSN 1867-8610, Vol. 3, no 4, 3851-3876 p.Article in journal (Refereed)
    Abstract [en]

    Within the framework of aerosol deposition to vegetation we present a specially designed leaf wash-off method used in a wind-tunnel based study, where leaves of Quercus robur L. were exposed to NaCl aerosols. We summarise the principles and illustrate the method for two types of substances, the chloride ion and the sodium ion, and for two levels of aerosol exposure prior to leaf washing. On the average, in the low-exposure experiments (S1), the 1st (2nd) wash-off step provided 90% (96%) of the amount of Cl− on the leaves. In the high-exposure experiments (S2) the corresponding values were 96% and 99%. For sodium, the general dynamics resembles that of chloride, but the amounts washed off were, in both series, on the average below what would be expected if the equivalent ratio in the tunnel aerosol were to be preserved. Na+ showed adsorption and/or absorption at the leaf surfaces. The difference between the mean values of the amounts of chloride and of sodium washed off in S1 was not statistically significant, the mean Na+ to Cl− difference as a fraction of Cl− being minus 18%±27%; corresponding values for S2 were minus 16%±9%, however (p<0.05). In the latter case, 101±57 μequiv Na+ per m2 of leaf area were missing for the equivalent relationship 1:1 with Cl− to be met. Although uncertainties are thus large, this indicates the magnitude of the Na+-retention. The method is suitable not only for chloride, an inexpensive and easy-to-handle tracer, but also for sodium under exposure at high aerosol concentrations. Our findings will help design further studies of aerosol/forest interactions.

  • 5.
    Yuan, Yunxia
    KTH, School of Electrical Engineering (EES), Space and Plasma Physics.
    Atmosphere density measurements using GPS data from rigid falling spheres2017In: Atmospheric Measurement Techniques Discussions, ISSN 1867-8610, E-ISSN 1867-8610Article in journal (Refereed)
    Abstract [en]

    Atmospheric density profiles in the stratosphere and mesosphere are determined by means of low cost Global Positioning System (GPS) receivers on in situ rigid falling spheres released from a sounding rocket. Values below an altitude of 80 km are obtained. Aerodynamic drag relates atmospheric densities to other variables such as velocities of spheres, drag coefficients,and reference area. The densities are reconstructed by iterative solution. The calculated density is reasonably accurate,with deviation within 10% with respect to the European Centre for Medium-range Weather Forecasts ( ECMWF) reference value. The atmospheric temperature and wind profiles are obtained as well, and compared to independent data.

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