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Ridged sea ice characteristics in the arctic from a coupled multicategory sea ice model
Stockholms universitet, Naturvetenskapliga fakulteten, Meteorologiska institutionen (MISU).
Stockholms universitet, Naturvetenskapliga fakulteten, Meteorologiska institutionen (MISU). Swedish Meteorological and Hydrological Institute, Sweden.
Stockholms universitet, Naturvetenskapliga fakulteten, Meteorologiska institutionen (MISU). Swedish Meteorological and Hydrological Institute, Sweden.
2012 (Engelska)Ingår i: Journal of Geophysical Research: Oceans, ISSN 2169-9291, Vol. 117, nr C8Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

In this study, a multicategory sea ice model with explicit ice classes for ridged and rafted ice was used to examine the evolution of deformed ice during the period 1980-2002. The results show that (1) ridged ice comprises roughly 45-60% of Arctic sea ice volume and 25-45% of the sea ice area, (2) most of the perennial ice consists of ridged ice, and (3) ridged ice exhibits a small seasonal variability. Our results also show an increase in mean ridged ice thickness of 4-6 cm yr(-1) during the summer in an area north of the Canadian Archipelago and a corresponding decrease in the East Siberian Sea and Nansen Basin. At the same time, Arctic sea ice age has been observed to decline and ice drift speed to increase during the simulation period. We connect these findings with a modeled regional increase in the production rate of ridged ice. Comparison of the multicategory model and a two category reference model shows a substantially increased ice production rate due to a more frequent occurrence of leads, resulting in an ice thickness increase of up to 0.8 m. Differences in ice physics between the multicategory and reference models also affect the freshwater content. The sum of liquid and solid freshwater content in the entire Arctic Ocean is about 10% lower and net precipitation (P-E) is about 7% lower as compared to the reference model.

Ort, förlag, år, upplaga, sidor
2012. Vol. 117, nr C8
Nationell ämneskategori
Meteorologi och atmosfärforskning
Forskningsämne
atmosfärvetenskap och oceanografi
Identifikatorer
URN: urn:nbn:se:su:diva-80754DOI: 10.1029/2010JC006936ISI: 000302857600001OAI: oai:DiVA.org:su-80754DiVA, id: diva2:557886
Anmärkning

AuthorCount:4;

Tillgänglig från: 2012-10-01 Skapad: 2012-09-27 Senast uppdaterad: 2014-10-06Bibliografiskt granskad
Ingår i avhandling
1. Ridged sea ice modelling in climate applications
Öppna denna publikation i ny flik eller fönster >>Ridged sea ice modelling in climate applications
2013 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
Abstract [en]

This work aims to increase our understanding of the nature of large scale features of sea ice from a dynamics point of view.Sea ice plays an important part in the exchange of heat and humidity between sea and air and thus is an important component of the climate system. Its physical presence also directly impacts the various forms of life such as diatoms, polar bears and humans alike.The dynamics of sea ice affect both weather and climate, through the large scale drift in the Arctic from the Siberian coast towards Fram Strait, through creation of cracks in the ice called leads or polynyas, and through ridging and other mechanical deformations of ice floes.In this work, we have focused on modelling of ridged ice for a number of reasons. Direct observations of the internal ice state is very difficult to perform and in general, observations of sea ice are either sparse or of limited information density. Ridged ice can be seen as the memory of high ice stress events, giving us a view on these highly dynamic events. Ridging is of major importance for the ice thickness distribution, as the thickest ice can only be formed through mechanical processes. Further, ridged ice is of direct interest for anyone conducting shipping through seasonal or perennial ice covered seas as it can form impenetrable barriers or in extreme even cases crush a ship caught within the ice pack.

To this end, a multi-category sea ice model, the HELsinki Multi category Ice model (HELMI), was implemented into the Rossby Centre Ocean model (RCO). HELMI has explicit formulations for ridged and rafted ice, as well as sub-grid scale ice thickness distribution (a feature shared with other multi category models) and an ice strength based on energetics. These features give RCO better representation of sub-grid scale physics and gives us the possibility to study the deformed ice in detail.

In paper I we look at the change in behaviour in the Arctic as the ice becomes more mobile, leading to a slight increase in modelled ridged ice volume in the central Arctic, despite a general trend of a decreasing ice cover.Paper II takes us to the Baltic Sea and the possibilities of modelling ridge ice concentration with a statistical model.In Paper III we investigate how the diminishing ice cover in future scenarios affects the biological activity in the Baltic Sea.Finally Paper IV investigates how the ice stress and the internal ice force can be interpreted in terms of ice compression on the ship scale.

Ort, förlag, år, upplaga, sidor
Department of Meteorology, Stockholm University, 2013. s. 37
Nyckelord
Arctic ocean, Baltic Sea, sea ice, ice dynamics, numerical modelling, climate, ice deformation, ice compression, physical and biogeochemical interactions
Nationell ämneskategori
Oceanografi, hydrologi och vattenresurser
Forskningsämne
atmosfärvetenskap och oceanografi
Identifikatorer
urn:nbn:se:su:diva-93977 (URN)978-91-7447-767-2 (ISBN)
Disputation
2013-10-22, William-Olssonsalen, Geovetenskapens hus, Svante Arrhenius väg 14, Stockholm, 10:00 (Engelska)
Opponent
Handledare
Anmärkning

At the time of the doctoral defence the following paper was unpublished and had a status as follows: Paper 4: Manuscript

Tillgänglig från: 2013-09-30 Skapad: 2013-09-22 Senast uppdaterad: 2018-01-11Bibliografiskt granskad

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Av författaren/redaktören
Mårtensson, SebastianMeier, H. E. MarkusPemberton, Per
Av organisationen
Meteorologiska institutionen (MISU)
Meteorologi och atmosfärforskning

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