Characteristic Of Intensity Index And Climatic Changes Of Hadley Circulation From 1948 To 2004

The monthly intensity index of global zonal mean Hadley circulation is defined and calculated by using the NCEP/NCAR reanalysis monthly wind data from 1948 to 2004, as well as Hadley circulation from east longitude 110 to 120. Then the trend variation, interannual variation and interdecadal variation are analyzed based on the index we also investigate relation between Hadley circulation to sea surface temperature and ENSO. At last we study the relation between Hadley circulation from 110 to 120 and large scale climate anomaly over China. The main contents and results are as follows.(1) There are two obvious Hadley circulation on both hemisphere from January to December when global zonal mean. The Hadley circulation from east longitude 110 to 120 represents updraft over north hemisphere and obvious circulation over south hemisphere from May to September and represents obvious circulation both hemisphere from October to next April. The zonal difference and seasonal change of Hadley circulation are great. The Hadley circulation is more active in winter hemisphere .(2) The intensity index of Hadley circulation is defined and calculated by using 4 key regions of 3 levels wind data for the southern/northern hemisphere and the global. Results indicate that the index we calculate can denote Hadley circulation intensity reasonably .Climatic changes of Hadley circulation intensity indicate that Hadley circulation index is increased in the northern hemisphere except the months from July to September ,as well as the trend variation of the southern hemisphere except May. There are extremely difference of interannual variation and interdecadal variation of both hemispheres.(3)Correlation analysis of interannual shows significant negative relation between global zonal mean Hadley circulation index and SOI. The interannual variation of Hadley circulation intensity is high related with ENSO.The global zonal mean Hadley circulation of both hemispheres show obvious positive relation with SST of equator, especial the east Pacific Ocean of the equator and the Indian Ocean, and negative related with SST of the eastern ocean of Australia and SST of northern Pacific Ocean.(4)In recent 50 years, The relations between Hadley circulation from east longitude 110 to 120 over northern hemisphere and temperature and rainfall in China have noticeable time variability on status from October to next April.There will be less precipitation and lower temperature in most area of China when the Hadley circulation is strong, In contrast* There will be more rainfall and higher temperature in most area when the Hadley circulation is weak. But from May to September the Hadley circulation show positive relation with rainfall and temperature except in June.