The Study On Some Problems Of The Climate Change In Global Land Precipitation Filed From 1920 To 2000

This paper comprehensively analyzed the global land precipitation dataset (G55wld0098) updated by Dr. Mike Hulme latestly and found that this dataset is accurate enough for describing the change of large scale precipitation. We also interpolate the data of precipitation records in global land(PREC/L) to replace the lack records of G55wld0098,and then get the 1920-2000 global precipitation field without lacking records.The study on precipitation field pointed out that most precipitation occurs in the monsoon area where exists the obvious rainy and dry season. The distribution of the precipitation is continuous alone the latitude.We analyzed the time series of global land average annual and seasonal precipitation. We found that the time series contains the obvious 2-7 years cycle in consistence with the ENSO cycle as well as the decadal cycle. The test indicated that there is a weak increasing trend in winter time series, but no apparent trend in other time series. We also compared the trend distribution of annual and seasonal precipitation in global land surface.A method is brought forth to identify the dry and flood years for precipitation during June to august in large scale area. The way to test the method is also given. We have used the method to identify the global dry and flood years for precipitation during June to august from 1920 to 2000. The result indicated that there is apparent relation between the global dry(flood) years and the warm(cold) events. The distribution of the global dry and flood years takes on decadal character.We also identify the dry and flood years for precipitation during June to august in north and south hemisphere. No obvious connection is found between the north hemisphere dry(ftood) years and the south hemisphere dry(flood) years.Further more, the dry and flood years for precipitation during June to august in Asia-Europe, Africa, Australia,North America,South America are identified respectively. We discussed the possible relation of the dry and flood years among the continents.We divided the global june-august precipitation field into 34 subareas and pointed out that there exists evident teleconnection among the june-august precipitation in these subareas.