Characteristics Of Spatial And Temporal Distribution Of Winter Precipitation In Eastern China And Its Relationship With Atmospheric Circulation And SST

Based on the winter precipitation data at 160 stations in China, the NCEP/NCAR reanalysis and the NOAA ERSST data during 1951/1952-2012/2013, the characteristics of the temporal and spatial variation of the winter precipitation in Eastern China during 62 years and its relationships with atmospheric circulation and sea surface temperature are studied. On this basis we analyze the differences of the characteristics of atmospheric circulation between more and less precipitation years in North China and southern China, respectively. In addition, the effects of sea surface temperature in different regions to the precipitation in North China and southern China are investigated respectively. The results show that:(1) The spatial distribution of precipitation in Eastern China shows two modes of consistent changes in Eastern China and an out-of-phase relationship between southern and northeastern China. The 62 years winter precipitation in Eastern China are categorized into 4 basic precipitation types:1+type(consistent increased in eastern China)、1-type(consistent decreased)、2+type(more in southern China and less in northern China)、2-type(less in the south and more in the north).(2) 1+type years shows weaker Siberian High and Aleutian Low, with the intensity of East Asian trough and Ural ridge both weakened and weaker upper-level jet stream. The East Asian winter monsoon is weaker in Eastern China; 1-type years are approximately opposite. During 2+type years, the intensity of East Asian trough and Ural ridge strengthened in the high latitude region and weakened in the low latitude region, which caused the winter monsoon weaker in southern China and stronger in northeast China; 2-type years are almost opposite. The main water vapor transports source of the winter precipitation in Eastern China is the Bay of Bengal and south sea. During 1+and 1-type years, SST in the North Pacific has significant change; During 2+and 2- type years, SST in the equatorial central and eastern Pacific has obvious change, which may be affected by ENSO cold and warm phase.(3) The interannual variability of winter precipitation in North China is significant. During more(less) winter precipitation years, Siberian High is weaker(stronger),and Aleutian low intensity is also weaker(stronger).Prevalent northwest wind in North China is weaker(stronger) at 850 hPa, the intensity of East Asian winter monsoon is also weaker(stronger). At 500 hPa,the intensity of East Asian trough and Ural ridge both weakened.Two dominating water vapor transports affect winter precipitation in North China are from south sea of China and the low latitude western Pacific to the east of south sea.A significant positive correlation exists between the winter precipitation in North China and the SST in westerly drift region to the east of Japan during previous summer,it is the same case between the winter precipitation in North China and the nearby yellow sea and bohai sea region in winter.(4) The winter precipitation and its interannual variation in southern China is significant. During more winter precipitation years, Siberian High is weaker and further north, the Aleutian low intensity is also weakened in the sea of Japan and its east. At 850 hPa, the East Asian winter monsoon is obviously weaker. At 500 hPa,the intensity of East Asian trough and Ural ridge both weakened, southwest airflow in front of the south branch trough is strengthened. During less precipitation years, the atmospheric circulation is approximately opposite. Water vapor transports from south sea and the Bay of Bengal are the main source of winter precipitation in southern China. Significant positive correlations exist between the winter precipitation in southern China and the SST in the equatorial central and eastern Pacific. The winter precipitation in southern China is closely linked to ENSO cycle.