An analysis of precipitation data from the Antarctic base Faraday/Vernadsky

摘要

A recent study on cloud observations reports an increase in total cloud cover at Faraday/Vernadsky since 1960 in the annual and wintertime data. The aim of this present study is to investigate whether this increase in total cloud cover has influenced the precipitation in this region. For this purpose, precipitation observations at the Antarctic base Faraday/Vernadsky between 1960 and 1999 were analysed. A positive trend, significant at the 5% level, was found in the number of precipitation events recorded during winter, showing an increase of 13 events per decade. The annual number of precipitation days has increased by 5.7 per decade during the period of investigation, with highest increase rates being observed in winter and autumn. The characteristics of these findings confirm that results previously published though trends presented here are ~50% smaller due to a more thorough data quality control of the observational data. These results indicate that an increase in total cloud cover at Faraday/Vernadsky observed since 1960 in the annual and wintertime data is reflected in higher numbers of precipitation events and days. Analyses of the precipitation type found an increase in the proportion of events of non-frozen precipitation, which is significant (1% level) on an annual basis as well as in spring and autumn (both significant at 5% level). This is a clear manifestation of the year round temperature increase observed over the Antarctic Peninsula. The increase in non-frozen precipitation will have reduced the albedo in the region and will thus have contributed to the temperature-albedo feedback. To refreeze rain that is draining through glaciers energy is extracted from the surrounding ice, thereby physically corroding the ice. This will have contributed to the observed retreat of glaciers around the Antarctic Peninsula. As non-frozen precipitation falling on frozen ground cannot be stored but instead runs off, less water will be available for the ecosystem.