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  1. Book ; Thesis: Dynamik des arktischen Meereises - Validierung verschiedener Rheologieansätze für die Anwendung in Klimamodellen

    Kreyscher, Martin

    Dynamics of Arctic sea ice - validation of different rheology schemes for the use in climate models

    (Berichte zur Polarforschung ; 291)

    1998  

    Title variant Dynamics of Arctic sea ice - validation of different rheology schemes for the use in climate models
    Author's details Martin Kreyscher
    Series title Berichte zur Polarforschung ; 291
    Keywords Wechselwirkung ; Validierung ; Sedimenttransport ; Meereis ; Mathematisches Modell ; Rheologie ; Klima ; Rheologische Eigenschaft ; Arktis ; Nordpolarmeer
    Language German
    Size 116 S., Ill., graph. Darst., Kt.
    Publisher Alfred-Wegener-Inst. für Polar- und Meeresforschung
    Publishing place Bremerhaven
    Document type Book ; Thesis
    Thesis / German Habilitation thesis Univ., Diss.--Bremen, 1998
    Note Literaturverz. S. [110] - 116
    Database Former special subject collection: coastal and deep sea fishing

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  2. Book ; Thesis: Dynamik des arktischen Meereises - Validierung verschiedener Rheologieansätze für die Anwendung in Klimamodellen

    Kreyscher, Martin

    Dynamics of Arctic sea ice - validation of different rheology schemes for the use in climate models

    (Berichte zur Polarforschung ; 291)

    1998  

    Title variant Dynamics of Arctic sea ice - validation of different rheology schemes for the use in climate models
    Author's details Martin Kreyscher
    Series title Berichte zur Polarforschung ; 291
    Keywords Wechselwirkung ; Validierung ; Sedimenttransport ; Meereis ; Mathematisches Modell ; Rheologie ; Klima ; Rheologische Eigenschaft ; Arktis ; Nordpolarmeer
    Language German
    Size 116 S., Ill., graph. Darst., Kt.
    Publisher Alfred-Wegener-Inst. für Polar- und Meeresforschung
    Publishing place Bremerhaven
    Document type Book ; Thesis
    Thesis / German Habilitation thesis Univ., Diss.--Bremen, 1998
    Note Literaturverz. S. [110] - 116
    Database Library catalogue of the German National Library of Science and Technology (TIB), Hannover

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  3. Book: Dynamik des arktischen Meereises - Validierung verschiedener Rheologieansaetze fuer die Anwendung in Klimamodellen = Dynamics of Arctic Sea Ice - Validation of Different Rheology Schemes for the Use in Climate Models

    Kreyscher, Martin

    1998  Volume 291, Page(s) 116

    Abstract: Die Meereisbedeckung in den Polarregionen beeinflusst die Wechselwirkungen zwischen Ozean und Atmosphaere nachhaltig. Aufgrund der hohen Oberflaechenreflektivitaet und der Reduzierung turbulenter Waermefluesse wirkt Meereis als eine isolierende Schicht ... ...

    Abstract Die Meereisbedeckung in den Polarregionen beeinflusst die Wechselwirkungen zwischen Ozean und Atmosphaere nachhaltig. Aufgrund der hohen Oberflaechenreflektivitaet und der Reduzierung turbulenter Waermefluesse wirkt Meereis als eine isolierende Schicht zwischen dem Ozean und der darueberliegenden Atmosphaere. Die Eisdicke und die Bildung von offenen Wasserflaechen werden neben thermodynamischen Prozessen durch die Dynamik des Meereises (Eisbewegung und -deformation) bestimmt. Darueberhinaus stellt der Suesswasserfluss, der mit der Bewegung des Meereises verbunden ist, einen bedeutenden Antriebsmechanismus fuer die globale thermohaline Zirkulation dar. Die Dynamik des Meereises wird ihrerseits stark durch interne Spannungen, die aufgrund der mechanischen Festigkeit der Meereisdecke entstehen, beeinflusst. Ziel dieser Dissertation ist es, eine optimale Meereisrheologie fuer Klimasimulationen zu bestimmen. Es wird eine Hierarchie aus vier Meereisrheologien untersucht. Diese enthaelt eine viskos-plastische Rheologie, ein Cavitating-Fluid-Modell, eine kompressible Newtonsche Fluessigkeit und ein einfaches Freie-Drift-Modell mit Geschwindigkeitskorrektur. Fuer den Vergleich werden fuer alle Modelle identische Modellgitter, Landmasken und Antriebsfelder verwendet. Die atmosphaerischen Antriebe fuer einen 17-jaehrigen Zeitraum stammen von Reanalysen des National Centre of Environmental Prediction (NCEP), waehrend die ozeanischen Antriebsdaten aus jaehrlich gemittelten Waermefluessen und geostrophischen Stroemungen bestehen, die aus einem gekoppelten Meereis-Ozean-Modell abgeleitet wurden. Fuer die Modellvalidierung werden taegliche Geschwindigkeiten von Driftbojen aus Satellitendaten abgeleitete Driftfelder, Eisdicken aus Echolotmessungen und Eiskonzentrationsdaten von passiven Mikrowellenradiometern verwendet. Alle Beobachtungen gehen in quantitative Fehlerfunktionen ein, die signifikante Unterschiede zwischen den Modellen aufzeigen. Zusaetzlich wird der Eisexport durch die Framstrasse fuer die verschiedenen Modelle untersucht. Das viskos-plastische Modell simuliert die realistischen Eisdriftstatistiken, taeglichen bis ueber zwoelf Monate gemittelten Geschwindigkeiten, sommerlichen Eisausdehnungsanomalien und Eisexport durch die Framstrasse. Im Gegensatz dazu zeigen die Resultate des sehr vereinfachten Freie-Drift-Modells mit Geschwindigkeitskorrektur deutliche Abweichungen sowohl bei den Driftcharakteristiken als auch bei den Eisdicken und dem Eisexport. Der kompressible Newtonsche Ansatz kann das uebermaessige Auftuermen des Eises in der zentralen Arktis nicht verhindern und zeigt deutliche Unterschiede im mittleren Zyklus des Eisexports durch die Framstrasse im Vergleich mit den Ergebnissen des viskos-plastischen Modells. Das Cavitating-Fluid-Modell zeigt aufgrund der vernachlaessigten Scherkraefte markante Unterschiede in den Statistiken der Driftgeschwindigkeiten und der raeumlichen Verteilung der Eisdicke. (gekuerzt)
    Keywords Eis ; Statistik ; Fernerkundung ; Kombinationswirkung ; Turbulenz ; Globale Aspekte ; Zirkulation ; Klimasimulation ; Fluessiger Stoff ; Satellit ; Waermefluss ; Atmosphaere ; Rheologie ; Klimamodell ; Ozean ; Polargebiet ; Thermodynamik ; Hydrodynamik ; Modellierung ; Vergleichsuntersuchung
    Language German
    Document type Book
    Database OPAC and Environmental database (ULIDAT) of The Federal Environment Agency (UBA)

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  4. Book: Dynamik des arktischen Meereises - Validierung verschiedener Rheologieansaetze fuer die Anwendung in Klimamodellen

    Kreyscher, Martin

    1998  Volume 291, Page(s) 116 S.

    Keywords Klimamodell
    Language German
    Document type Book
    Database OPAC and Environmental database (ULIDAT) of The Federal Environment Agency (UBA)

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    Inter-library loan at ZB MED

    Your chosen title can be delivered directly to ZB MED Cologne location if you are registered as a user at ZB MED Cologne.

  5. Book ; Thesis: Dynamik des arktischen Meereises - Validierung verschiedener Rheologieansätze für die Anwendung in Klimamodellen

    Kreyscher, Martin

    Dynamics of Arctic sea ice - validation of different rheology schemes for the use in climate models

    (Berichte zur Polarforschung ; 291)

    1998  

    Title variant Dynamics of Arctic sea ice - validation of different rheology schemes for the use in climate models
    Author's details Martin Kreyscher
    Series title Berichte zur Polarforschung ; 291
    Keywords Wechselwirkung ; Validierung ; Sedimenttransport ; Meereis ; Mathematisches Modell ; Rheologie ; Klima ; Rheologische Eigenschaft ; Arktis ; Nordpolarmeer
    Language German
    Size 116 S., Ill., graph. Darst., Kt.
    Document type Book ; Thesis
    Thesis / German Habilitation thesis Zugl.: Bremen, Univ., Diss., 1998
    Note Intermediärsprache: Englisch ; Literaturverz. S. [110] - 116
    Database Johann Heinrich von Thünen-Institut, Federal Research Institute for Rural Areas, Forestry and Fisheries

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  6. Book ; Online: At surface behaviour of juvenile and female southern elephant seals from King George Island from expeditions JUB1996 and JUB1997, supplementary data to: Bornemann, Horst; Kreyscher, Martin; Ramdohr, Sven; Martin, Thomas; Carlini, Alejandro R; Sellmann, Lutz; Pl?tz, Joachim (2000): Southern elephant seal movements and Antarctic sea ice. Antarctic Science, 12(1), 3-15

    Bornemann, Horst / Carlini, Alejandro R / Kreyscher, Martin / Martin, Thomas / Pl?tz, Joachim / Ramdohr, Sven / Sellmann, Lutz

    2000  

    Abstract: Between December 1996 and February 1997, weaned pups and postmoult female southern elephant seals (Mirounga leonina) were fitted with satellite transmitters at King George Island (South Shetlands). Of the nine adult females tracked for more than two ... ...

    Abstract Between December 1996 and February 1997, weaned pups and postmoult female southern elephant seals (Mirounga leonina) were fitted with satellite transmitters at King George Island (South Shetlands). Of the nine adult females tracked for more than two months, three stayed in a localized area between the South Shetlands and the South Orkneys. The other six females travelled southwest along the coast of the Antarctic Peninsula up to the Bellingshausen Sea. Two of them then moved far northeast and hauled out on South Georgia in October. One female was last located north of the South Shetlands in March 1998. In total, eight females were again sighted on King George Island and six of the transmitters removed. The tracks of the weaners contrasted with those of the adults. In January, five juveniles left King George Island for the Pacific sector ranging about four weeks in the open sea west of the De Gerlache Seamounts. Three of them returned to the tip of the Antarctic Peninsula in June, of which one was last located on the Patagonian Shelf in November 1997. A computer animation was developed to visualize the animal movements in relation to the extent and concentration of sea ice. The juveniles avoided sea ice while the adults did not. The latter displayed behavioural differences in using the pack ice habitat during winter. Some females adjusted their movement patterns to the pulsating sea ice fringe in far-distant foraging areas while others ranged in closed pack ice of up to 100 %. The feeding grounds of adult female elephant seals are more closely associated with the pack ice zone than previously assumed.
    Language English
    Dates of publication 2000-9999
    Size Online-Ressource
    Publisher PANGAEA - Data Publisher for Earth & Environmental Science
    Publishing place Bremen/Bremerhaven
    Document type Book ; Online
    Note This dataset is supplement to doi:10.1017/S095410200000002X
    DOI 10.1594/PANGAEA.586824
    Database Library catalogue of the German National Library of Science and Technology (TIB), Hannover

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  7. Article ; Online: Results of the Sea Ice Model Intercomparison Project

    Kreyscher, Martin / Harder, Markus / Lemke, Peter / Flato, Gregory M.

    Evaluation of sea ice rheology schemes for use in climate simulations

    2000  

    Abstract: A hierarchy of sea ice rheologies is evaluated on the basis of a comprehensive set of observational data. The investigations are part of the Sea Ice Model Intercomparison Project (SIMIP). Four different sea ice rheology schemes are compared: a viscous‐ ... ...

    Abstract A hierarchy of sea ice rheologies is evaluated on the basis of a comprehensive set of observational data. The investigations are part of the Sea Ice Model Intercomparison Project (SIMIP). Four different sea ice rheology schemes are compared: a viscous‐plastic rheology, a cavitating‐fluid model, a compressible Newtonian fluid, and a simple free drift approach with velocity correction. The same grid, land boundaries, and forcing fields are applied to all models. As verification data, there are (1) ice thickness data from upward looking sonars (ULS), (2) ice concentration data from the passive microwave radiometers SMMR and SSM/I, (3) daily buoy drift data obtained by the International Arctic Buoy Program (IABP), and (4) satellite‐derived ice drift fields based on the 85 GHz channel of SSM/I. All models are optimized individually with respect to mean drift speed and daily drift speed statistics. The impact of ice strength on the ice cover is best revealed by the spatial pattern of ice thickness, ice drift on different timescales, daily drift speed statistics, and the drift velocities in Fram Strait. Overall, the viscous‐plastic rheology yields the most realistic simulation. In contrast, the results of the very simple free‐drift model with velocity correction clearly show large errors in simulated ice drift as well as in ice thicknesses and ice export through Fram Strait compared to observation. The compressible Newtonian fluid cannot prevent excessive ice thickness buildup in the central Arctic and overestimates the internal forces in Fram Strait. Because of the lack of shear strength, the cavitating‐fluid model shows marked differences to the statistics of observed ice drift and the observed spatial pattern of ice thickness. Comparison of required computer resources demonstrates that the additional cost for the viscous‐plastic sea ice rheology is minor compared with the atmospheric and oceanic model components in global climate simulations.
    Subject code 290
    Language English
    Publisher AGU (American Geophysical Union)
    Publishing country de
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  8. Article ; Online: Sea ice circulation in the Laptev Sea and ice export to the Arctic Ocean

    Alexandrov, Vitaly Y. / Martin, Thomas / Kolatschek, Josef / Eicken, Hajo / Kreyscher, Martin / Makshtas, Alexandr P.

    Sea ice circulation in the Laptev Sea and ice export to the Arctic Ocean: Results from satellite remote sensing and numerical modeling

    2000  

    Abstract: Sea ice circulation in the Laptev Sea and ice exchange with the Arctic Ocean have been studied based on remote sensing data and numerical modeling. Ice drift patterns for short‐ and long‐term periods were retrieved from successive Okean radar images and ... ...

    Abstract Sea ice circulation in the Laptev Sea and ice exchange with the Arctic Ocean have been studied based on remote sensing data and numerical modeling. Ice drift patterns for short‐ and long‐term periods were retrieved from successive Okean radar images and Special Sensor Microwave/Imager data for the winters 1987/1988 and 1994/1995. Seasonal and interannual variabilities of ice drift in the Laptev Sea and ice exchange with the Arctic Ocean during the period from 1979 to 1995 were studied with a large‐scale dynamic‐thermodynamic sea ice model. During an “average year,” sea ice was exported from the Laptev Sea through its northern and eastern boundaries, with maximum and minimum export occurring in February and August, respectively. The winter ice outflow from the Laptev Sea varied between 251,000 km2 (1984/1985) and 732,000 km2 (1988/1989) with the mean value of 483,000 km2. Sea ice was exported into the East Siberian Sea mostly in summers with the mean value of 69,000 km2. Out of the 17 investigated summers, 12 were characterized by sea ice import from the Arctic Ocean into the Laptev Sea through its northern boundary. Magnitude and direction of ice export from the Laptev Sea corresponded with the large‐scale Arctic Ocean drift patterns during periods of prevailing cyclonic or anticyclonic circulation. Based on a semiempirical method that has been validated with the large‐scale model and satellite data, ice exchange between the Laptev Sea and the Arctic Ocean during the period from 1936 to 1995 has been estimated as 309,000km2 with strong interannual variability and no significant trend apparent.
    Subject code 551 ; 290
    Language English
    Publisher AGU (American Geophysical Union)
    Publishing country de
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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