Interactions between katabatic winds and polynyas at the Adelie Coast, eastern Antarctica


Abstract

Satellite-derived outgoing longwave radiation (OLR), surface temperature and sea ice concentration off the coast of Adelie-Land were analyzed together with two wind data sets. For the time period 1974-1990 available radiative flux data showed a slight increase of OLR suggesting a 4 degrees C warming would be observed from space for this polar region over a century. The observed increase is in agreement with Dumont d'Urville, the only ground station within the study area, which displayed a similar temperature increase, and with the general temperature increase which has been observed for the high southern latitudes. Further, a correlation between the development of open water areas (polynyas) and the appearance of extremely strong offshore winds can be drawn. In the study area the influence of the katabatic wind on the sea ice extends 20 to 100 km offshore. Sea ice motion further off the coast seems to be more dominated by synoptic scale weather systems. Events of strong winds can have a weakening effect on the coastal sea ice which can lead to a much more sensitive reaction of the sea ice in response to following anomalous wind events.


Financial support was obtained in part by a grant to the Alaska Climate Research Center from the State of Alaska, and from NSF Grant DPP 9070969 and Grant No. 9413879.