NUMERICAL SIMULATION OF SSTA IMPACTS OVER THE GLOBAL OCEAN ON THE ANOMALOUS CIRCULATION OVER EURASIA IN JANUARY 2008

摘要

In this paper,we discussed the features of atmospheric circulations over Eurasia as a response to sea surface temperature anomalies (SSTAs) over the tropical Indian Ocean,the equatorial Pacific,Kuroshio and the North Atlantic.Our results are shown as follows: (1) CAM3.0,driven by the combined SSTAs over the four oceanic regions,can simulate well the features of anomalous atmospheric circulations over Eurasia in January 2008,indicating that the effects of the SSTAs over these four regions were one of the key causes of the anomalous systems over Eurasia.(2) The SSTAs over each key region contributed to the intensification of blocking over the Urals Mountains and a main East Asian trough.However,the influence of the SSTAs over individual oceanic regions differed from one another in other aspects.The SSTAs over the North Atlantic had an impact on the 500-hPa anomalous height (Z500A) over the middle-high latitudes and had a somewhat smaller effect over the low latitudes.For the warm SSTAs over Kuroshio,the subtropical high was much stronger,spread farther north than usual,and had an anomalous easterly that dominated the northwest Pacific Ocean.The warm SSTAs over the tropical Indian Ocean could have caused a negative Z500A from West Asia to Middle Asia,a remarkably anomalous southwesterly from the Indian Ocean to the south of China and an anomalous anticyclone circulation over the South China Sea-Philippine Sea region.Because of the La Nia event,the winter monsoon was stronger than normal,with an anomalously cooler northerly over the southeastern coastal areas of China.(3) The combined effects of the SSTAs over the four key regions were likely more important to the atmospheric circulation anomalies of January 2008 over Eurasia than the effects of individual or partly combined SSTAs.This unique SSTA distribution possibly led to the circulation anomalies over Eurasia in January 2008,especially the atmospheric circulation anomalies over the subtropics,which were more similar to those of the winter El Ni?o events than to the circulation anomalies following La Nia.