The Study On The Global Land Precipitation Associated With ENSO During 1920-2000

This paper summarized the timetable of ENSO event during 1920-2000 by analyzing the previous result of other scholar.The global land monthly precipitation data (PREC/C) are used to investigate the relation between the global land annual precipitation and ENSO during 1948-2000,and the results of composite analysis are tested with Monte Carlo simulations. Results indicate that global land annual precipitation reduced significantly in large-scale areas in warm events years. Remarkable areas are the equatorial West Pacific, North China, equatorial Central America, north of Bengal Gulf and Nepal, Eastern Australia, West India and South Pakistan, east of Lena River and West Europe and Wilkes in Antarctic. In warm events years, the areas where precipitation increased were less. Main areas are Chile and Argentina of South American, Somali, Kenya and Tanzania in East Africa, Turkey, Iraq and Iran in Middle East, Libya and Algeria in North Africa, Namibia in Southwest Africa and Botswana and Zimbabwe in south of Africa. Statistical tests show that the acreage whose global annual land precipitation decreases is greater than which increases, and more prominent. The results in this paper are compared with previous studies. It is also pointed out that, the decadal variety of ENSO has not evident effect to the decadal variety of precipitation of above areas. However, the influence of warm events after 1980's to the drought of Eastern Australia and North China is more notable than before.We also use the data from 1920-2000, which were made by Chen through interpolating the data of precipitation records in global land (PREC/L) to replace the lack records of the global land precipitation dataset updated by Or. Mike Hulme, to study the global and regional abnormal character of precipitation in the year when ENSO events had taken place during 1920-2000.lt shows that, the precipitation decreased in warm events, increased in cold events. The period of time of the influence of cold events to precipitation is shorter than the one of warm events. The number of the month when precipitation is abnormal of warm events after 1976 is little than before, however, the number of the month when precipitation is abnormal of cold events after 1976 is more than before. When ENSO is happened , the global precipitation has decadal variety between the time before 1976 and after 1976.We also analyzed the character of the variety of precipitation in different region during the six months before(after) the beginning year of ENSO. At last, we study the geographical distribution of the month when the most extreme happened.