Improvement Of Calculation Scheme Of Similarity Coefficient For The Non-uniform Network And The Types Of Chinese Precipitation And Temperature

Based on monthly average precipitation and air temperature data of160weather stations in China from1951-2010, along with NCEP/NCAR reanalysis data and sea surface temperature (SST) data reconstructed by NOAA, a calculation method of homogenization revised similarity coefficient is given, and interannual similarity of unusual precipitation and air temperature types is analyzed. Based on this analysis, the exact types of seasonal precipitation and air temperature are given, and corresponding circulation characteristics and SST anomalous characteristics are researched. The results are as follow:1) The station network is dense in Eastern China, sparse in Western China. The weight function of national average before revised is larger in Eastern China, so that the similarity coefficient before revised largely reflects the characteristics of Eastern China. The weight of national average in Western China increases by the station network homogeneity adjustment, so that the national overall similarity coefficient after network adjustment changes a lot. Therefore, the degree of interannual similarity of anomaly element fields is more objectively reflected by the similarity coefficient after network adjustment.2) The anomaly percentage fields of seasonal precipitation (the anomaly fields of air temperature) are divided into five (four) types. The spatial distribution characteristics of different types of precipitation (air temperature) are quite different.3) From five kinds of summer precipitation distribution type corresponding to500hPa height anomaly fields, the key systems influence on precipitation distribution types are the trough for the Qinghai-Tibet Plateau and north to Lake Baikal region, the subtropical high, the trough along the east Asian coast and high pressure ridge near the Ural Mountains. From all of the five kinds of summer precipitation distribution corresponding to100hPa height anomaly fields, the key systems of the influence on the precipitation are all the South Asia high pressure. The water vapor transport paths impact on the precipitation distribution types are also different, but the corresponding divergence characters of integrated water vapor transport are convergence centers exist at several big precipitation areas.4) The SST key area affected five kinds of summer precipitation are mainly the north Pacific, the sea of Okhotsk, the equator Middle East Pacific and the east sea of Japan islands, the mid-latitude Pacific OCean, the north Pacific, the Kuroshio area, etc. The different SST key areas of distribution types are differentiated.5) From four kinds of winter temperature distribution type corresponding to the sea level pressure anomalies fields, the key systems of influence on the temperature are all Siberian high pressure. From four kinds of winter temperature distribution type corresponding to500hPa height anomaly fields, the key systems affected temperature distribution are polar vortex, the east Asian trough, the European trough and the ridge from the Tibetan plateau to Lake Baikal,etc. The Northern Hemisphere polar vortex size and strength corresponding four types of winter temperature distribution also have their own characteristics.6) The SST key area affected winter temperatures are mainly in the northeast Pacific OCean, the area nearby kuroshio, near the Hawaiian islands, Kuroshio extension area, from the equator Middle East Pacific OCean to the west coast of North America and the west wind drift region, etc. The different SST key areas of distribution types are differentiated.