Using the NCEP/NCAR and JRA-25 monthly analysis data from 1979 to 2011,this paper analyzes the interdecadal variations of winter(Dec.–Feb.)mean surface air temperature(SAT)over East Asia by means of the empirical ort...Using the NCEP/NCAR and JRA-25 monthly analysis data from 1979 to 2011,this paper analyzes the interdecadal variations of winter(Dec.–Feb.)mean surface air temperature(SAT)over East Asia by means of the empirical orthogonal function(EOF)analysis method.Two dominant modes were extracted,with the leading mode basically depicting a sign consistent SAT variation and the second mode describing a meridional dipole structure between the northern and southern parts of East Asia.These two modes can explain more than 60%of the variance.The leading mode is closely related to the intensity of Siberian high and the East Asian winter monsoon.The second mode exhibits a notable interdecadal shift in the late 1990s,with a turning point around1996/1997.Winter SAT in the northern(southern)part of East Asia tends to be cooler(warmer)since the late 1990.Winter sea level pressure(SLP)differences between 1997–2011 and 1979–1996 show negative(positive)anomalies over southern(northern)Eurasia.At 500-hPa,an anomalous blocking high occurs over northern Eurasia,while a cyclone anomaly appears over northern East Asia.In addition,the upper-level East Asian jet stream tends to shift northward and become stronger after the late 1990.Indeed,the interdecadal shift of winter SAT over East Asia is dynamical consistent with changes of the large-scale atmospheric circulation in the late 1990s.The result indicates that previous autumn sea surface temperature(SST)in the North Atlantic Ocean,the Northern Indian Ocean and the western North Pacific Ocean,as well as sea ice concentration(SIC)in the northern Eurasia marginal seas and the Beaufort Sea also experienced obvious changes in the late 1990s.In particular,the interdecadal shifts of both SST in the North Atlantic Ocean and SIC in the Arctic Ocean and its marginal seas are well coherent with that of the winter SAT over East Asia.The results indicate that the interdecadal shift of East Asian winter SAT may be related to changes in the North Atlantic SST and the Arctic SIC in the late 1990s.展开更多
基金supported by the National Natural Science Foundation of China (41221064 and 40875052)the Calling Project of China (GYHY200906017)+1 种基金the Ship Channel in Arctic (201205007-7)the Basic Research Foundation of CAMS (2010Z003)
文摘Using the NCEP/NCAR and JRA-25 monthly analysis data from 1979 to 2011,this paper analyzes the interdecadal variations of winter(Dec.–Feb.)mean surface air temperature(SAT)over East Asia by means of the empirical orthogonal function(EOF)analysis method.Two dominant modes were extracted,with the leading mode basically depicting a sign consistent SAT variation and the second mode describing a meridional dipole structure between the northern and southern parts of East Asia.These two modes can explain more than 60%of the variance.The leading mode is closely related to the intensity of Siberian high and the East Asian winter monsoon.The second mode exhibits a notable interdecadal shift in the late 1990s,with a turning point around1996/1997.Winter SAT in the northern(southern)part of East Asia tends to be cooler(warmer)since the late 1990.Winter sea level pressure(SLP)differences between 1997–2011 and 1979–1996 show negative(positive)anomalies over southern(northern)Eurasia.At 500-hPa,an anomalous blocking high occurs over northern Eurasia,while a cyclone anomaly appears over northern East Asia.In addition,the upper-level East Asian jet stream tends to shift northward and become stronger after the late 1990.Indeed,the interdecadal shift of winter SAT over East Asia is dynamical consistent with changes of the large-scale atmospheric circulation in the late 1990s.The result indicates that previous autumn sea surface temperature(SST)in the North Atlantic Ocean,the Northern Indian Ocean and the western North Pacific Ocean,as well as sea ice concentration(SIC)in the northern Eurasia marginal seas and the Beaufort Sea also experienced obvious changes in the late 1990s.In particular,the interdecadal shifts of both SST in the North Atlantic Ocean and SIC in the Arctic Ocean and its marginal seas are well coherent with that of the winter SAT over East Asia.The results indicate that the interdecadal shift of East Asian winter SAT may be related to changes in the North Atlantic SST and the Arctic SIC in the late 1990s.
