Atmospheric response to the extreme Arctic sea ice conditions in 2007

Abstract

An atmospheric general circulation model driven with the observed 2007 extreme Arctic sea surface temperatures and sea ice concentrations responds with higher surface air temperature over northern Siberia and the Eastern Arctic Ocean (+3 K), increased heat uptake of the ocean in summer (+40 W m−2) and increased oceanic heat losses in fall (−60 W m−2) compared to a climatological scenario. A pronounced low sea level pressure anomaly over the Eastern Arctic (−200 Pa) reinforces a sea level pressure dipole over the Arctic that has been observed to become an increasingly important feature of the Arctic atmospheric circulation in summer. The anomalous pressure distribution contributes to sea ice transport from the Eastern Arctic and is likely to reinforce the original sea ice extent anomaly. The results thus support assessments of observational data over recent years that sea ice loss may feed back onto the atmospheric circulation in the northern hemisphere. The resulting late summer / early fall (JAS) atmospheric anomalies are very robust, they appear in virtually all of the 40 realizations of the experiment. However, we find no significant continuation of the atmospheric signal into the winter as has been suggested based on atmospheric observational data.