Satellite-derived outgoing longwave radiation,surface temperature and sea ice concentration off the coast of Adélie-Land,Eastern Antarctica

Summary Outgoing longwave radiation (OLR) as seen from satellite (NOAA-series), and sea ice concentration in Mer Dumont d'Urville, Eastern Antarctica were analyzed. For the time period 1974–1990 available radiative flux data showed a slight increase of 1.8 W/m² or 1% for the period. If thistrend should continue — trends over a 16-year period in any geophysical data is a rather questionable concept in isolation — a 4°C warming would be observed from space for this polar region over a century. The observed increase is, however, in agreement with Dumont d'Urville, the only ground station within the study area, which displayed a similar temperature increase (Periard and Pettré, 1991). Further it is in agreement with the general temperature increase which has been observed for the high southern latitudes (Boden et al., 1990). In addition, models of climatic change due to increased CO₂ and other trace gases predict for polar regions values of similar size.Sea ice concentration showed a slight decrease for the time period 1974–1989, for which data were available. However, a relationship existed between the radiative flux and the ice concentration, not only for the actual data, but also for the deviation series with the annual cycles removed. A correlation factor of –0.74 was found; the sensitivity for an increase of 10% in ice concentration was –2.9 W/m². This represents a temperature change as seen from space of about 1°C for a 10% change in sea ice concentration.With 7 Figures