Articles | Volume 16, issue 8
Research article
18 Apr 2016
Research article |  | 18 Apr 2016

Precipitation and synoptic regime in two extreme years 2009 and 2010 at Dome C, Antarctica – implications for ice core interpretation

Elisabeth Schlosser, Barbara Stenni, Mauro Valt, Anselmo Cagnati, Jordan G. Powers, Kevin W. Manning, Marilyn Raphael, and Michael G. Duda

Abstract. At the East Antarctic deep ice core drilling site Dome C, daily precipitation measurements were initiated in 2006 and are being continued until today. The amounts and stable isotope ratios of the precipitation samples as well as crystal types are determined. Within the measuring period, the two years 2009 and 2010 showed striking contrasting temperature and precipitation anomalies, particularly in the winter seasons. The reasons for these anomalies are analysed using data from the mesoscale atmospheric model WRF (Weather Research and Forecasting Model) run under the Antarctic Mesoscale Prediction System (AMPS). 2009 was relatively warm and moist due to frequent warm air intrusions connected to amplification of Rossby waves in the circumpolar westerlies, whereas the winter of 2010 was extremely dry and cold. It is shown that while in 2010 a strong zonal atmospheric flow was dominant, in 2009 an enhanced meridional flow prevailed, which increased the meridional transport of heat and moisture onto the East Antarctic plateau and led to a number of high-precipitation/warming events at Dome C. This was also evident in a positive (negative) SAM (Southern Annular Mode) index and a negative (positive) ZW3 (zonal wave number three) index during the winter months of 2010 (2009). Changes in the frequency or seasonality of such event-type precipitation can lead to a strong bias in the air temperature derived from stable water isotopes in ice cores.

Short summary
Striking differences in the atmospheric flow and thus weather conditions in 2009 and 2010 at the Antarctic deep ice core drilling site Dome C were investigated using a mesoscale atmospheric model and precipitation measurements, and implications for interpretation of ice cores are discussed. Stable isotope ratios are commonly used to derive paleotemperatures and are strongly influenced by the prevailing atmospheric flow regime, namely a strong zonal flow or a highly meriodional flow.
Final-revised paper