Impact Factors of Summer Temperature on Largescale Circulationin Northeast China
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Abstract:
Based on the monthly temperature data of 53 observational stations in Northeast China from 1961 to 2010 and the NCEP/NCAR monthly reanalysis data of the wind field, geopotential height field, sea level pressure field, and specific humidity field, the impact factors of large scale circulation characteristics on summer temperature in Northeast China are analyzed. The 200 hPa zonal wind shear index, which is suitable for describing the summer temperature in Northeast China is defined, and the predict method of the index are provided. Results show that there is close relationship between summer temperature in Northeast China and the dipole of the Okhotsk blocking high in the sea level pressure (SLP) in the central North Pacific. The 500 hPa geopotential height field over Northeast China is abnormally high, corresponding to the summer temperature in Northeast China abnormally high, and vice versa corresponding to the summer temperature in Northeast China abnormally low. The 850 hPa vector wind field, the whole layer moisture flux field, and the 200 hPa vector wind field present a cyclonic circulation over Northeast China, corresponding to the summer temperature in Northeast China abnormally low, and vice versa corresponding to the summer temperature in Northeast China abnormally high. At the same time, water vapor from the Bay of Bengal is also an impact factor of summer temperatures in Northeast China. There is a significant positive correlation between 200 hPa zonal wind shear index and temperature in Northeast China. Large index corresponds to high summer temperature in Northeast China, and vice versa corresponding to the summer temperature in Northeast China abnormally low. There is a close relationship between the tropical Indian Ocean and the Pacific SST from April to May and the 200 hPa zonal wind shear index.