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«Changing Polar Regions 25th International Congress on Polar Research March 17-22, 2013, Hamburg, Germany German Society for Polar Research Edited by ...»

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Interannual variability, however, is high and shows a strong dependence on the coastal polynya activity. On average 5.2 Sv of dense shelf water are exported, but since a large fraction is diluted by mixing with ambient water and leaves the Weddell Sea at intermediate levels, not all of this water contributes to the formation of Weddell Sea Deep/Bottom Water.

"Changing Polar Regions" - 25th International Congress on Polar Research 2013 THE MODERN DEPOSITIONAL ENVIRONMENT IN POTTER COVE,

KING GEORGE ISLAND, ANTARCTICA

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King George Island belongs to the South Shetland Islands that are located north of the northern tip of the Antarctic Peninsula (AP). It is situated slightly north of the area where climatic warming in Antarctica is strongest. In places the annual mean temperatures increased by 0.5 K per decade through the past 60 years (Faraday/Vernadsky Station, AP). The air temperatures in the immediate working area increased by about 0.35 K per decade (Schloss et al. 2012) during the past 20 years which is still in the range of the recovery of temperatures from the Little Ice Age maximum to the end of the 19th century.

IMCOAST, a multidisciplinary international project investigates the modern and the late Holocene environmental development of the fjordic environment of south King George Island. In this part of the project we aim at reconstructing the modern sediment distribution in the inner part of Potter Cove using an acoustic ground discrimination system (RoxAnn) and more than136 ground-truth samples.

The impact of the warming trend is clearly visible in the form of retreating glaciers and melting ice sheets, loss of sea ice and strong meltwater discharge into the coastal zone. Potter Cove is a small fjord characterized by a series of moraine ridges produced by a tidewater glacier (Fourcade Glacier). Presumably, the farthest moraine is not much older than about 500 years (LIA maximum), hence the sediment cover is rather thin as evidenced by high resolution seismic data (see presentation by Wittenberg et al.). Since a few years at least the better part of the tidewater glacier has retreated onto the island’s mainland. It is suggested that such a fundamental change in the fjord’s physiography has also changed sedimentation patterns in the area. Potter Cove is characterized by silty-clayey sediments in the deeper inner parts of the cove. Sediments are coarser (fine sand to coarse sands and boulders) in the shallower areas; they also coarsen from the innermost basin to the mouth of the fjord. Textural structures follow the seabed morphology, i.e. small v-shaped passages through the moraine ridges. The glacier still produces large amounts of turbid melt waters that enter the cove at various places. We presume that very finegrained sediments settle from the meltwater plumes and are eventually transported by mid-depth or even bottom currents towards the mouth of the fjord. Older sediments that are more distal to the glacier front and sediments in shallower places "Changing Polar Regions" - 25th International Congress on Polar Research 2013 e.g. on top of the moraine ridges) become increasingly overprinted by coarser sediments from the shallow areas of the fjord. These areas are prone to wave induced winnowing effects as well as disturbances by ploughing icebergs. It can be concluded that coarsening of the fjord sediments will continue while supply of finegrained meltwater sediments might cease due to exhaustion of the reservoirs.

"Changing Polar Regions" - 25th International Congress on Polar Research 2013 RECENT SNOW COVER CHANGES OF LEMMING HABITATS IN

HIGH ARCTIC GREENLAND AS DERIVED FROM LANDSAT TM

IMAGERY

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Snow cover as an essential component of the ecology of high arctic species has been monitored by remote sensing as part of a long term project documenting lemming cycles in North East Greenland. For this purpose, data available via Landsat TM imagery has been used to assess the spatial and temporal changes of the snow pack in the Karupelv Valley study area within the last three decades. Based on the analyses of 237 images, we could assess ongoing changes both in the phenology of the snow melt in late spring as well as in the establishment of the autumnal snow pack. Despite a great interannual variability of these parameters, significant long term trends suggest an increase by more than 3 weeks of the length of snow free period that affects demographic processes within this high arctic terrestrial community.

"Changing Polar Regions" - 25th International Congress on Polar Research 2013 IKAPOS: UNTERSUCHUNG DER ATMOSPHÄRISCHEN

GRENZSCHICHT IM KATABATISCHEN WIND UND ÜBER DER

NORTH WATER POLYNJA MIT FLUGZEUGMESSUNGEN

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Das flugzeuggestützte Experiment IKAPOS (Investigation of Katabatic winds and Polynyas during Summer) wurde im Juni 2010 durchgeführt. Ziel der Studie war die Untersuchung des katabatischen Windsystems unter sommerlichen Bedingungen in Küstenbereich von Nordwest-Grönland und die Erfassung von Wechselwirkungsprozessen von Atmosphäre, Meereis und Ozean über der North Water (NOW) Polynja. Die Messungen erfolgten mit dem Forschungsflugzeug POLAR5 des Alfred-Wegener-Instituts (AWI, Bremerhaven). Neben den Navigationssystemen und einer meteorologischen Basis-Instrumentierung war das Flugzeug mit Strahlungssensoren, zwei Laser-Höhenmessern, Videokameras und Digitalkameras ausgestattet. Zur Messung von turbulenten Wärme- und Impulsflussdichten wurde POLAR5 mit einem Turbulenz-System an einem Nasenmast instrumentiert (Datenrate 100 Hz).





Es konnten insgesamt sechs Forschungsflüge durchgeführt werden, davon zwei im katabatischen Windsystem über dem Humboldt- bzw. Steenstrup-Gletscher. Unter Bedingungen von schwachem synoptischen Antrieb ist das Windsystem sehr flach und erreicht Windstärken von 7-9m/s. Bei starkem synoptischen Antrieb werden bis zu 14m/s erreicht.

Über der NOW-Polynja wurde die voll turbulente, aber stabile Grenzschicht mit Windstärken zwischen 15 und 20 m s-1 vermessen. Aufgrund der sehr stabilen Schichtung mit einer Bodeninversion in den untersten 100-200 m wurden starke Kanalisierungseffekte im Bereich des Smith Sounds beobachtet. Mit Hilfe von Querschnitten konnte die Struktur eines Grenzschicht-Strahlstroms (low-level jet, LLJ) erfasst werden. Dieses mesoskalige LLJ-System führt zu einer bedeutsamen Erhöhung des Wind-induzierten Meereis-Exports aus Nares-Straße.

Zur Berechnung der turbulenten Flussdichten wurde die geeignete Mittelungslänge mit Hilfe der Spektren ermittelt. Dabei ergeben sich Längenskalen von 500 m–1000 m (Polynja) und 250m (katabatischer Wind). Der turbulente Fluss sensibler Wärme ist zur Oberfläche gerichtet und erreicht Werte von bis zu 30W/m².

Der IKAPOS-Datensatz ist dazu geeignet, die Güte von numerischen Modellen für sommerliche arktische Bedingungen zu überprüfen und trägt zum quantitativen Verständnis der Austauschprozesse über Polynjen und dem grönländischen Eisschild bei.

"Changing Polar Regions" - 25th International Congress on Polar Research 2013 BERICHTSKOLLOQUIUM SPP 1158: POLYNYA FORMATION

PROCESSES IN THE WEDDELL SEA REGION

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Coastal polynyas play an important role for the coupling between the components of the sea ice-ocean-atmosphere system in polar areas. They are associated with locally enhanced surface exchange processes, which have important consequences for the atmosphere, ocean processes, ice formation, gas exchange and biology. In the Weddell Sea, recurrent coastal polynyas form throughout the winter season, largely triggered by atmospheric forcing. The general perception in textbooks is that katabatic winds play the major role for this forcing.

The paper will highlight the atmospheric aspect of polynya formation and ice-oceanatmosphere interaction. The different forcing processes for strong offshore winds (katabatic, synoptic) are investigated using high-resolution (5km) atmospheric simulations of the non-hydrostatic atmosphere model COSMO for the winter 2008.

Different flow regimes such as katabatic winds, the barrier wind along the Antarctic Peninsula (AP) and flow over AP mountains can be identified as climatological signals. Katabatic wind dynamics are investigated by splitting the pressure gradient in the katabatic and synoptic components, respectively.

"Changing Polar Regions" - 25th International Congress on Polar Research 2013 PFALZ TRIFFT ANTARKTIS“

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Im November 2011 begannen unsere Aktivitäten zum Projekt „Coole Klassen“.

Mit der Anbahnung des Kontaktes zu Frau Kallfelz und der Bereitstellung von Materialien über Polarforschung stellten wir schnell eine Verknüpfung mit den Lehrplänen der Fächer Gesellschaftslehre und Naturwissenschaften in der Klassenstufe 5 her.

Fächerübergreifend erfuhren die Schülerinnen und Schüler Zusammenhänge zwischen der Polarforschung und den Themen „Orientierung auf der Erde“ und „Ökologie“.

Die Klasse brachte Information zu den Rahmenbedingungen der POLARSTERNExpedition in die Antarktis im Dezember 2011/Januar 2012 in Erfahrung und verfolgte mit großem Interesse die Blogs von Frau Kallfelz über die Internetpräsenz der Tageszeitung „Die Rheinpfalz“.

Die Kinder übten Kurzvorträge, vertieften ihre Kenntnisse über das Gradnetz und konnten ihre Kreativität bei der Erstellung von Pins unter Beweis stellen.

Sie verschafften sich damit Einblicke in die technischen Raffinessen des Forschungseisbrechers und der Neumayer-Station III. Weiterhin begriffen sie durch die Berichte über die Arbeiten der Forscherinnen und Forscher, dass das Forschen viel Mühe bei der Vorbereitung, Durchführung und Nachbereitung kostet.

Als Highlight erachteten die Schüler die Ankündigung, dass wir die AntarktisBesucherin Frau Kallfelz in die Schule einladen wollten. Jetzt war man noch motivierter sich über das „Ewige Eis“ zu informieren und Berichte in den Medien zu verfolgen. Meine Tutorin im Fach Naturwissenschaften führte in der Zwischenzeit einen Versuch zur Polschmelze durch.

Als die Zeitzeugin nun tatsächlich im April 2012 in der Schule eintraf und ihre Berichte, ihren Polaranzug und viele Versuchsaufbauten im Stationsbetrieb an die Schülerschaft brachte, wurden die Augen immer funkelnder und der Ehrgeiz mehr über die Polargebiete zu erfahren immer größer. Schnell wurden selbstgebastelte Pinguine zu Autogrammkarten umfunktioniert, um ein Souvenir von diesem besonderen Erlebnis zu haben.

Als Bonbon für die eifrige, interessierte und disziplinierte Arbeit durfte die Truppe kurz vor den Sommerferien das Pfalzmuseum für Naturkunde in Bad-Dürkheim besuchen. Die Kinder bestaunten das Eisbären- und das Pinguin-Präparat, den Wegweiser von Neumayer I, ein Modell der La Rochelle und viele andere Exponate.

Sie hatten keine Mühe sich mit dem Audioguide im Museum zu bewegen und waren ein weiteres Mal intensiv mit polaren Themen befasst und sehr beeindruckt.

"Changing Polar Regions" - 25th International Congress on Polar Research 2013 In Klassenstufe 9 behandelte ich im Fach Geschichte mit einer Schülergruppe die Anfänge der Polarforschung und ermöglichte den Schülern, Vergleiche zu den Expeditionen zu Zeiten von Roald Amundsen bzw. Robert Falcon Scott und heutiger Forschungsreisen zu ziehen.

Sehr spannend für mich selbst war der Austausch mit den betreuenden Lehrerinnen und Lehrern anderer „Cooler Klassen“. Es eröffnete mir weitere Ideen für fächerübergreifenden, handlungsorientierten Unterricht.

"Changing Polar Regions" - 25th International Congress on Polar Research 2013 TRACING THE ORIGIN OF ARCTIC DRIFTWOOD

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Arctic driftwood is exceptional regarding its spatial dispersal distance and ability to be preserved over most of the Holocene, and therefore represents a unique paleoenvironmental archive at the interface of marine and terrestrial environments. Here, we present the world’s largest compilation of 1500 Arctic driftwood samples from Svalbard and the east coast of Greenland. All wooden remains were in situ differentiated between natural (with root-collar) and artificial (logged) material, and include a maximum variety of sample dimensions and characteristics. Each sample was macro- and microscopically analyzed and wood anatomically identified. Treering widths of ~400 logged pines were measured and cross-dated against regional chronologies from Siberia. Our results reveal the existence of five conifers (Pinus sylvestris, Pinus sibirica, Picea sp., Larix sp., Abies sp.) and three broadleaf species (Populus sp., Salix sp., Betula sp.). Pinus sylvestris represents 40% of the driftwood and likely originates from Eurasia and Siberia, which was confirmed by first crossdating trials. Anatomical wood identification and consideration of the complex boreal species distribution is essential for precisely tracing the origin of Arctic driftwood. The future aim is to elaborate a circumpolar network of tree-ring chronologies for all genera in the different boreal catchments, which will guarantee a precise spatial and temporal driftwood classification, and thus enable the reconstruction of boreal climate, ocean currents and postglacial uplift.

"Changing Polar Regions" - 25th International Congress on Polar Research 2013 DEGLACIATION OF THE WEST ANTARCTIC CONTINENTAL SHELF

IN THE AMUNDSEN SEA SECTOR SINCE THE LAST GLACIAL

MAXIMUM

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