The Key Influence Areas Of Low-frequency Disturbance Energy Of Different Scales And Their Influence On The Abnormal Weather In East Asia

In order to study the characteristics of low-frequency disturbance energy distribution and its impact on the weather in East Asia,we used the daily average NCEP/NCAR reanalysis data from 1976 to 2016 and the daily precipitation data at 2426 stations in China to use band-pass filtering and wave packet propagation.The diagnostic method analyzes the propagation and distribution of low-frequency disturbance energy at different scales 10-20 d,and further studies the propagation of low-frequency disturbance energy during the Meiyu rainy year(1998 and 2002)and the low-frequency disturbance energy for the abnormal years of Meiyu.influences.The following conclusions have been drawn:(1)The climatological distribution of disturbance wave packages at different scales shows that the global low-frequency disturbance energy gradually weakens from the lower level to the upper level,with the highest low-frequency disturbance energy at 850 hPa being the strongest;the low-frequency disturbance energy in the southern hemisphere is higher than the northern hemisphere.In the northern hemisphere,the low-frequency disturbance energy intensity in winter is larger than that in summer.Compared with the northern hemisphere,the southern hemisphere is opposite.In summer,the low-frequency disturbance energy is greater than in winter.In the process of low-frequency disturbance energy intensity changes,the lowfrequency energy changes in the low-latitude regions are smaller than those in the mid-high latitudes.In total,there are four low-frequency disturbance energy bands symmetrical to the equator in the world,with zonal distributions of 30°N,60°N,30°S,and 60°S.Most of the low-frequency disturbance energy centers are located in the interface between the mainland and the ocean.(2)The propagation analysis of disturbance wave packets at different scales shows that at 200 hPa and 500 hPa,low-frequency disturbance energy is transmitted in the zonal direction.At 200 hPa and 500 hPa,the center of low-frequency disturbance energy in winter is basically located in the ocean,and in summer,the center of low-frequency disturbance energy located in the ocean moves westward or eastward to land.In the sea level pressure and 850 hPa,the low-frequency disturbance energy propagates in radial direction.In winter,the low-frequency disturbance energy center is basically located in the high latitude area.In summer,the low-frequency disturbance energy center in the high latitude area moves toward the low latitude equator.(3)There is a significant positive correlation between SCS summer monsoon and small-scale low-frequency disturbance energy.The intensity of the SCS summer monsoon is more closely related to the distribution of low-level wave packets,and is not strongly related to the high-level wave packet distribution characteristics.The key low-frequency disturbance energy at sea level pressure and 850 hPa geopotential heights are the key areas of China's South China Sea and East China Sea(0-30°N,90°E-130°E)and Russia's Far East(60°N-75°N,120°E-160°E).(4)The latitudinal and radial propagation of typical sea level pressure and 850 hPa height wave envelopes for typical anomalous Meiyu rain indicate that the sea level pressure and the 850 hPa height disturbance energy latitude in the middle and lower reaches of the Yangtze River in the Fengmei year is mainly due to the accumulation of the west-central Pacific Ocean.The impact and the cumulative impact of the southward propagation from the Mongolian Plateau.The year of dry plum is just the opposite.The low-level perturbation energy propagates in the opposite direction both in the longitude direction and in the latitude direction compared to Fengmei years.