中高纬瞬变涡旋活动对我国东部夏季降水的影响OACSTPCD

Based on the reanalysis data JRA-55(Japanese 55-year Reanalysis)of the Japanese Meteorological Agency(JMA)and the satellite precipitation data of the Climate Prediction Center(CPC)in the United States from 1981 to 2020,the characteristics of transient eddies and their effects on the summer precipitation anomalies in eastern China were analyzed,and the possible mechanisms for these effects were discussed.Results show that the region from Mongolia to Northeast and North China is not only an active region of transient eddies,but also a large value region of transient eddy transport.The meridional transport of heat and moisture that plays a dominant role in the transient eddy transport process,is an important source of heat and moisture in middle-to-high latitude.According to the intensity of the heat and moisture transport variability of the transient eddies,the key regions of the transient heat and moisture transport were identified as(45°-60°N,100°-130°E)and(35°-50°N,100°-120°E),respectively,and the transient heat and moisture indices were defined.The regression results with the summer precipitation anomalies in eastern China show that the transient eddy activities have significant effects on the summer precipitation in eastern China.The anomalies of transport of heat,moisture and momentum by the middle-to-high latitude synoptic scale transient eddies has formed a feedback to the mean flow through the wave-flow interaction process,resulting in anomalies of seasonal mean circulation,moisture distribution and moisture transport,and thus causing precipitation anomalies under the combined influence of thermal,dynamic and moisture conditions.