Monsoon circulation over the Amur River basin during catastrophic flood and extreme drought in summer

Abstract

Two opposite Far East monsoon summer seasons over the Amur River basin are investigated which caused the extreme drought and fires in 2008 and catastrophic flood in 2013. It is shown that in the low-water summer of 2008 due to blocking processes, polar-front cyclones were almost absent over the Amur, were short, had fuzzy frontal systems, and did not bring precipitation. The summer monsoon circulation was suppressed, and in the Amur region continental air masses dominated over marine tropical air. On the contrary, the summer of 2013 was characterized by unprecedented cyclonic activity and the sharp strengthening ofthe moisture-laden monsoon flow from the ocean. As a result, the intensification of summer monsoon precipitation and the Amur flood were observed. It was established that the Far East summer monsoon anomalies are associated with the large-scale transformation of atmospheric circulation over the Asia-Pacific region.