A study of the far distance tropical cyclone torrential rainfalls in Shandong Province

Using data of precipitation in Shandong province，normal meteorologic al observation data, typhoon yearbooks and NCEP/NCAR data during 1971-2003, the statistical climate characteristics and the composing circumfluence of the torrential rainfalls in Shandong province caused by remote tropical cyclones landing or activating on the coast of South China were analyzed. The synoptic model of the far distance tropical cyclone torrential rainfalls in Shandong province was established. The budgets of composed water vapor and enthalpy of having and not having far distance tropical torrential rainfalls in Shandong were analyzed. The result indicated: the annual average of far distance tropical cyclone torrential rainfalls in Shandong caused by the interaction of the tropical cyclone landing or activating on the coast of South China, the west wind system in middle latitude and the subtropical high is 2.5/year. This torrential rainfall's range was very wide; its intensity was very strong. The torrential rainfalls occurring time were lagged the tropical cyclone landing time. When the tropical cyclone which caused the torrential rainfall in Shandong was landing on the coast of South China, there were south easterly or southerly jets at the low level of troposphere in the eastern part of center of the tropical cyclones toward Mainland China; westerly circulations at mid high latitude were weaker and lay over higher latitudes. The northerly winds in westerly band met the southerly winds on the west edge of subtropical high over western Pacific in Shandong region at 500 hPa. Effected by low system at the lower layer of troposphere (850-700 hPa), Shandong was dominated by cyclonic circulation. After tropical cyclone landing, the southerly jet near the center of cyclone extended northwardly and arrived at Shandong through the ridge line of the subtropical high over western Pacific. The transportation channels of water vapor and enthalpy between the center of tropical cyclone and Shandong was established and the warmer and wetter atmosphere carried toward Shandong continuously. From 12 to 48 hours after tropical cyclone landing, there were a great deal of water vapor and enthalpy importing, the wet and warm airflow and the westerly wind band airflow converged, and then updraft was produced, so the torrential rainfall occurred. 