Recent climate variability at the Antarctic Peninsula and coastal Dronning Maud Land, based on stable water isotope data


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Hanno.Meyer [ at ] awi.de

Abstract

The Antarctic Peninsula (AP) is a hotspot of the recent climate instability of the Antarctic Continent. The highest warming trends are observed at north (Esperanza station +0.4°C decade-1) and the west (+0.6°C decade-1) of AP. On the other hand, the interior of the continent and most of coastal East Antarctica does not show any clear warming (cooling) trend. Only isolated spots of warming and cooling around the coastal areas are detected. In this thesis, the recent climate variability of two coastal regions of Antarctica is investigated. This study is mainly based on the analysis of stables water isotope of firn cores and precipitation samples from these regions. First, the northern Antarctic Peninsula and the George Island (South Shetland Islands) are investigated. From the combined isotope composition of precipitation and a backward trajectories model, it was found that the precipitation at this region originates mainly from the South Pacific sector (warmer) and the Amundsen-Bellingshausen Sea (colder). From a firn core retrieved at the AP divide (Plateau Laclavere), a first accumulation rate (2350 kg m-2 a-1) has been derived for this unexplored region. The stable water isotope composition of firn cores shows a statistically significant correlation with air temperature (T air), and to relative humidity and sea ice conditions at the nearby Amundsen-Bellingshausen Sea. Moreover, a marked correlation is found between the isotope composition and the Southern Annular Mode (SAM). Hence, SAM is the principal mode of the climate variability on the region in a sub-annual to inter-annual time scale, as observed from the time series analysis of meteorological data and form long ice core records (Gomez Plateau). The second area investigated is located in coastal Dronning Maud Land (DML), East Antarctica. DML shows no T air trends for the last 20 years from meteorological records. The stable water isotope composition of four cores from the hinterland and one core from Ekströmisen, expand the meteorological record back to ~1892 AD. From these records no significant trend is observed from the δ18O time series since 1960. According, no temporal changes of the accumulation rates are observed, which strongly vary from the coast (360 kg m-2 a-1) to the hinterland (1260 kg m-2 a-1). In contrary to AP no consistent correlation are found between SAM and long isotope records, and only sporadic periods (e.g.: 1970-2000) of statistically significant correlations occurs between SAM and δ18O (T air). Moreover, the strongest SAM and δ18O (T air) correlation are found for the summer season. The recent climate variability of coastal Antarctica is clearly modulated by the major climate mode (SAM and ENSO), however both records for both DML and the AP are too short to reflect a reliable climatic picture of the post-industrial era. Therefore we propose two new localities for coring campaigns aiming to retrieve a medium depth (150-200 m ice) core in AP (Plateau Laclavere) and a medium to depth (>300 m) at DML (Halvfarryggen).



Item Type
Thesis (PhD)
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Primary Division
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Not peer-reviewed
Publication Status
Published
Eprint ID
45165
Cite as
Fernandoy, F. (2011): Recent climate variability at the Antarctic Peninsula and coastal Dronning Maud Land, based on stable water isotope data , PhD thesis, Universität Potsdam.


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