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  • 2010-2014  (19)
  • 2010  (19)
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  • 2010-2014  (19)
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  • 1
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    Einfluss von atmophärischen Antriebsdaten auf Simulationen der Dynamik der Laptev-See_Polynjen mit dem Meereis-Ozean-Modell FESOM (2010)
    In:  [Poster] In: DACH 2010 Meteorologentagung, 20.09.-24.09.2010, Bonn .
    Details
    Publication Date: 2014-12-17
    Description: Die Polynjen der Laptev-See nehmen eine Schlüsselrolle in den Schelfgebieten der sibirischen Arktis ein. Hier wird ein beachtlicher Teil des Meereisvolumens im arktischen Ozean gebildet. Zur Simulation der Dynamik der Polynjen und Quantifizierung der Eisproduktion verwenden wir das numerische Meereis-Ozean-Modell FESOM (Finite Element Sea Ice-Ocean-Model) (AWI Bremerhaven). In den bisherigen Simulationen wurde das FESOM mit täglichen NCEP (National Centers for Environmental Prediction) Daten angetrieben. Für den 1. April bis 9. Mai 2008 untersuchen wir den Einfluss von folgenden verschiedenen Antriebsdaten: Tägliche und 6-stündliche NCEP/DOE (Department of Energy) Reanalysen 2 (1.875 ̊ x 1.875 ̊), 6-stündliche NCEP/NCAR (National Centers for Atmospheric Research) Reanalysen 1 (2.5 ̊ x 2.5 ̊), 6-stündliche Analysen des GME (Globalmodell des Deutschen Wetterdienstes) (0.5 ̊ x 0.5 ̊) und hoch aufgelöste stündliche COSMO (Consortium for Small-Scale Modelling) Daten (5 km x 5 km). Vergleiche mit In-situ-Messungen des TRANSDRIFT XIII-2 Experiments 2008 zeigen, dass der Wind von allen atmosphärischen Antriebsdaten realistisch über dem Festeis wiedergegeben wird. Mit Ausnahme der FESOM-Simulationen mit täglichen NCEP-Daten werden die Öffnungs- und Schließvorgänge der Polynjen in guter Übereinstimmung mit AMSR-E (Advanced Microwave Scanning Radiometer - Earth Observing System) Produkten simuliert. Allerdings bestehen beträchtliche Diskrepanzen zwischen den Meereisproduktionsraten der unterschiedlichen Simulationen. Um die Eisproduktion in Polynjen zu quantifizieren sind stündliche, hoch aufgelöste atmosphärische Daten notwendig.
    Type: Conference or Workshop Item , NonPeerReviewed
    Format: text
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  • 2
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    Evaluation of simulated sea-ice concentrations from sea-ice(ocean models using satellite data and polynya classification methods (2010)
    In:  [Poster] In: Joint Russian-German Workshop on Research in the Laptev Sea Region, 08.11.-11.11.2010, St. Petersburg, Russia .
    Details
    Publication Date: 2014-12-09
    Type: Conference or Workshop Item , NonPeerReviewed
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  • 3
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    Abschätzung der Meereisproduktion in der Laptev-See mit dem Ozean-Meereismodell NAOSIM (2010)
    In:  [Poster] In: DACH 2010 Meteorologentagung, 20.09.-24.09.2010, Bonn .
    Details
    Publication Date: 2014-12-17
    Description: Fernerkundungsdaten haben eine kontinuierliche Abnahme des Meereises in den vergangenen 30 Jahren gezeigt, Klimamodelle prognostizieren eine anhaltende Abnahme für die Zukunft. Dies erfordert eine genauere Analyse der verursachenden Prozesse, der Trendentwicklung und der regionalen Variabilität. Dabei spielt die Laptev-See in der sibirischen Arktis eine bedeutende Rolle, da es hier, bedingt durch eine große Polynja-Aktivität, zur vermehrten Eisproduktion kommt. Zur näheren Untersuchung der verursachenden thermodynamischen und dynamischen Prozesse nutzen wir eine mit täglichen NCEP/NCAR-Daten angetriebene Simulation mit dem gekoppelten Ozean-Meereismodell NAOSIM (North Atlantic/Arctic Ocean-Sea Ice Model) von 1990-2008 mit 0.08° Auflösung. Aufgrund seiner realitätsnahen Wiedergabe des mittleren Jahresgangs und des negativen Trends der Eisbedeckung ist dieses Modell für die Auswertung gut geeignet. Die getrennte Analyse der thermodynamischen Eisproduktion bzw. Eisschmelze und der dynamischen Umverteilung für die gesamte Arktis bestätigt, dass im Bereich der Laptev-See die Eisproduktion im Mittel 850km3/a größer ist als die Eisschmelze. Dieses Eis wird von der Laptev-See in die zentrale Arktis exportiert. In der gesamten Arktis nimmt das Eisvolumen im Mittel um -450km3/a von 1990-2008 ab. usammenhänge zwischen der Eisproduktion der Laptev-See und des Eisvolumens der Arktis werden mittels einer Zeitreihenananlyse untersucht. Die Entstehungsgründe für Extremjahre (Bsp.: Minimum 2007, Maximum 1996) werden aufgezeigt und ihre regionalen Folgen in der Arktis diskutiert.
    Type: Conference or Workshop Item , NonPeerReviewed
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  • 4
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    Simulation of Laptev Sea polynya dynamics using the FESOM model with different atmospheric forces (2010)
    In:  [Poster] In: EGU General Assembly 2010, 02.05.-07.05.2010, Vienna, Austria .
    Details
    Publication Date: 2014-12-11
    Description: The Laptev Sea polynyas play a key role for the shelf areas of the Siberian Arctic due to their impact on ice production. Changes in polynya dynamics result in modified fluxes of energy, momentum and matter in the atmosphere-ocean-sea ice system. An improved understanding and quantification of polynya effects in the Laptev Sea can be achieved by high-resolution sea ice-ocean models. Here we use the well-established Finite Element Sea Ice-Ocean Model FESOM (5 km x 5 km) (AWI Bremerhaven). It consists of a hydrostatic primitive-equation ocean model and a dynamic-thermodynamic sea ice model. In our study the model is forced by 6-hourly GME analyses (0.5° x 0.5°), daily and 6-hourly NCEP/NCAR reanalyses (2.5° x 2.5°) and hourly COSMO data (5 km x 5 km) to investigate a polynya event during the TRANSDRIFT winter experiment 2008. The input data consists of 10 m-wind, 2 m-temperature and specific humidity, total cloudiness and precipitation rate. In order to test the quality of the forcing data, comparisons with in-situ have been performed. They show shortcomings of the atmospheric analyses model data with respect to the daily course of the temperature, but very good agreement for the wind. The opening process of a main polynya event on 29 April 2008 is represented with all atmospheric forcing fields (except the daily NCEP data) in a similarly good way. However, there are differences in direction and velocity of the icedrift and in the location and development of the polynyas. Small-scale structures are best represented by applying the high-resolution COSMO data. The maximum sensible heat flux is 220 W/m2, the maximum latent heat flux is 120 W/m2, the maximum advective ice thickness reduction is 5 cm/h and the maximum thermal ice thickness production is 5 mm/h.
    Type: Conference or Workshop Item , NonPeerReviewed
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  • 5
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    Verification of simulated sea-ice concentrations from sea-ice/ocean models using satellite data (2010)
    In:  [Poster] In: EGU General Assembly 2010, 02.05.-07.05.2010, Vienna, Austria .
    Details
    Publication Date: 2014-12-11
    Description: Sea-ice concentrations in the Laptev Sea simulated by the coupled North Atlantic – Arctic Ocean – Sea-Ice Model (NAOSIM) and Finite Element Sea-Ice Ocean Model (FESOM)are verified using sea-ice concentrations from AMSR-E satellite data and a polynya classification method for winter 2007/08. Simulated sea-ice fields from different model runs are compared with emphasis on the impact of an integrated fast-ice mask. Sea-ice models are not able to simulate polynyas realistically when used in their operational versions. Without fast ice, our investigations indicate that the simulation of large leads and smoothed sea-ice concentration fields compensates the absence of the polynyas. After implementation of a fast-ice mask the polynya location is realistically simulated, but the total open water area is largely overestimated. The study shows that further model improvements are necessary in order to achieve the important step from the simulation of large-scale features in the Arctic towards a more detailed simulation of smaller-scaled features (here polynyas) in an Arctic shelf sea.
    Type: Conference or Workshop Item , NonPeerReviewed
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  • 6
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    Implementation of a thermodynamic sea ice module in the NSP model COSMO and its impact on simulations for the Laptev Sea area in the Siberian Arctic (2010)
    In:  [Poster] In: Joint Russian-German Workshop on Research in the Laptev Sea Region, 08.11.-11.11.2010, St. Petersburg, Russia .
    Details
    Publication Date: 2014-12-22
    Description: Previous versions of the numerical weather prediction model COSMO (Consortium for Small-Scale Modeling) have used a constant sea ice surface temperature, but observations show a high degree of variability on sub-daily time-scales. To account for this, we have implemented a thermodynamic sea ice module in COSMO and performed simulations at a resolution of 15 km and 5 km for the Laptev Sea area in April 2008. Temporal and spatial variability of surface and 2m air temperature are verified by four automatic weather stations deployed along the edge of the West New Siberian Polynya during the TRANSDRIFT XIII-2 expedition and by surface temperature charts derived from MODIS satellite data. A remarkable agreement between the new model results and these observations demonstrates that the implemented sea ice module can be applied for short range simulations. Our COSMO simulations provide a high resolution and high quality atmospheric data set for the Laptev Sea for the period 14 to 30 April 2008. Based on this data set, we derive a mean total sea ice production rate of 0.53 km3/day for all Laptev Sea polynyas. Our results indicate that ice production in Laptev Sea polynyas has been overestimated in previous studies.
    Type: Conference or Workshop Item , NonPeerReviewed
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  • 7
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    Impact of Laptev Sea flaw polynyas on the atmospheric boundary layer and ice production using idealized mesoscale simulations (2010)
    In:  [Other] In: COSMO/CLM User Seminar, 02.03.-04.03.2010, Langen .
    Details
    Publication Date: 2014-12-11
    Description: The interaction between polynyas and the atmospheric boundary layer is examined in the Laptev Sea using the regional, non-hydrostatic Consortium for Small-scale Modelling (COSMO) atmosphere model. A thermodynamic sea-ice model is used to consider the response of sea-ice surface temperature to idealized atmospheric forcing. The idealized regimes represent atmospheric conditions that are typical for the Laptev Sea region. Cold wintertime conditions are investigated with sea-ice ocean temperature differences of up to 40 K. The Laptev Sea flaw polynyas strongly modify the atmospheric boundary layer. Convectively mixed layers reach heights of up to 1200 m above the polynyas with temperature anomalies of more than 5 K. Horizontal transport of heat expands to areas more than 500 km downstream of the polynyas. Strong wind regimes lead to a more shallow mixed layer with strong near-surface modifications, while weaker wind regimes show a deeper, well-mixed convective boundary layer. Shallow mesoscale circulations occur in the vicinity of ice-free and thin-ice covered polynyas. They are forced by large turbulent and radiative heat fluxes from the surface of up to 789 W m-2, strong low-level thermally induced convergence and cold air flow from the orographic structure of the Taimyr Peninsula in the western Laptev Sea region. Based on the surface energy balance we derive potential sea-ice production rates between 8 and 25 cm d-1. These production rates are mainly determined by whether the polynyas are ice-free or covered by thin ice and by the wind strength.
    Type: Conference or Workshop Item , PeerReviewed
    DOI: 10.3402/polar.v30i0.7210
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  • 8
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    Impact of Laptev Sea flaw polynyas on the atmospheric boundary layer and ice production using idealized mesoscale simulations (2010)
    In:  [Other] In: Joint Russian-German Workshop on Research in the Laptev Sea Region, 08.11.-11.11.2010, St. Petersburg, Russia .
    Details
    Publication Date: 2014-12-11
    Description: The interaction between polynyas and the atmospheric boundary layer is examined in the Laptev Sea using the regional, non-hydrostatic Consortium for Small-scale Modelling (COSMO) atmosphere model. A thermodynamic sea-ice model is used to consider the response of sea-ice surface temperature to idealized atmospheric forcing. The idealized regimes represent atmospheric conditions that are typical for the Laptev Sea region. Cold wintertime conditions are investigated with sea-ice ocean temperature differences of up to 40 K. The Laptev Sea flaw polynyas strongly modify the atmospheric boundary layer. Convectively mixed layers reach heights of up to 1200 m above the polynyas with temperature anomalies of more than 5 K. Horizontal transport of heat expands to areas more than 500 km downstream of the polynyas. Strong wind regimes lead to a more shallow mixed layer with strong near-surface modifications, while weaker wind regimes show a deeper, well-mixed convective boundary layer. Shallow mesoscale circulations occur in the vicinity of ice-free and thin-ice covered polynyas. They are forced by large turbulent and radiative heat fluxes from the surface of up to 789 W m-2, strong low-level thermally induced convergence and cold air flow from the orographic structure of the Taimyr Peninsula in the western Laptev Sea region. Based on the surface energy balance we derive potential sea-ice production rates between 8 and 25 cm d-1. These production rates are mainly determined by whether the polynyas are ice-free or covered by thin ice and by the wind strength.
    Type: Conference or Workshop Item , PeerReviewed
    DOI: 10.3402/polar.v30i0.7210
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    OceanRep: Talk
  • 9
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    Impact of Laptev Sea flaw polynyas on the atmospheric boundary layer and ice production using idealized mesoscale simulations (2010)
    In:  [Other] In: EGU General Assembly 2010, 02.05.-07.05.2010, Vienna, Austria .
    Details
    Publication Date: 2014-12-11
    Description: The interaction between polynyas and the atmospheric boundary layer is examined in the Laptev Sea using the regional, non-hydrostatic Consortium for Small-scale Modelling (COSMO) atmosphere model. A thermodynamic sea-ice model is used to consider the response of sea-ice surface temperature to idealized atmospheric forcing. The idealized regimes represent atmospheric conditions that are typical for the Laptev Sea region. Cold wintertime conditions are investigated with sea-ice ocean temperature differences of up to 40 K. The Laptev Sea flaw polynyas strongly modify the atmospheric boundary layer. Convectively mixed layers reach heights of up to 1200 m above the polynyas with temperature anomalies of more than 5 K. Horizontal transport of heat expands to areas more than 500 km downstream of the polynyas. Strong wind regimes lead to a more shallow mixed layer with strong near-surface modifications, while weaker wind regimes show a deeper, well-mixed convective boundary layer. Shallow mesoscale circulations occur in the vicinity of ice-free and thin-ice covered polynyas. They are forced by large turbulent and radiative heat fluxes from the surface of up to 789 W m-2, strong low-level thermally induced convergence and cold air flow from the orographic structure of the Taimyr Peninsula in the western Laptev Sea region. Based on the surface energy balance we derive potential sea-ice production rates between 8 and 25 cm d-1. These production rates are mainly determined by whether the polynyas are ice-free or covered by thin ice and by the wind strength.
    Type: Conference or Workshop Item , PeerReviewed
    Format: text
    DOI: 10.3402/polar.v30i0.7210
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  • 10
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    Air-sea-ocean interaction processes and impacts on polynya formation and sea ice production in the Laptev Sea of the Siberian Arctic (2010)
    In:  [Other] In: Joint Russian-German Workshop on Research in the Laptev Sea Region, 08.11.-11.11.2010, St. Petersburg, Russia .
    Details
    Publication Date: 2014-12-15
    Description: Processes of the exchange of energy and momentum at the sea ice-ocean-atmosphere interface are key processes for the polar climate system. Heat and moisture fluxes are strongly modulated by open water fractions associated with polynyas, having important consequences for the atmosphere, ocean processes, ice formation, brine release, gas exchange and biology. Our paper aims at the study of atmospheric processes forcing and maintaining polynyas in the Laptev Sea of the Siberian Arctic. This region is known as being a highly productive area for the formation of new ice throughout the winter season. We study polynya processes using passive satellite remote sensing data, high-resolution (5km) sea-ice/ocean and atmospheric models, as well as in-situ data obtained during experimental studies in that area. Passive microwave sensor data (SSM/I, AMSR) are used together with atmospheric reanalysis to characterize the long-term spatiotemporal characteristics of polynya events. A special focus lies on the detection of thin ice in polynya areas, which is studied using thermal infrared data (MODIS, AVHRR). Thin ice statistics combined with microwave data allows for estimations of ice production rates for the last decades. The NWP model COSMO is used together with the sea-ice/ocean model FESOM to study polynya dynamics. Model simulations are validated using satellite data and in-situ measurements from two campaigns in the Laptev Sea area.
    Type: Conference or Workshop Item , NonPeerReviewed
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