Researches On Interannual And Inter-decadal Variability Of Cross-Equatorial Flow

Based on NCEP/NCAR reanalysis wind field,height field,temperature, sea-level data from 1948 to 2006,the atmospheric heat sources from 1948 to 2002,and the rainfall data from 1979 to 2006,the interannual and inter-decadal variable characters of cross-equatorial flows in Eastern Hemisphere,and the impact factors are analyzed.Then the relationships between the cross-equatorial flows and the atmospheric heat sources are analyzed.Then we discuss their influences on the inter-hemispheric water vapor transport and on the Asian summer rainfall.Results show that:There are 5 cross equator flows channels in the eastern hemisphere.They are 45°E,90°E,105°E,125°E,150°E,and they are disparted to three types:Somali jet,Bengal bay CEF and Eastern Asian CEF.They all have interannual and inter-decadal variable.The interannual change of Eastern Asian CEF is distinctness and the intensity to stronger from weaker in 1975.The interannual change of Bengal bay CEF is take second place,and the intensity to weaker from stronger in 1975.The interannual change of SMJ is inconspicuous,and the change of the intensity is the same as Eastern Asian CEF.It is indicated that the relationships between the interannual change of the intensity of cross-equatorial flow and low-latitude circulation at southern and northern hemisphere,especially,the relationship between the intensity and pressure difference is osculation.The intensity of CEF and pressure difference has the same tendency.And the intensity of Somali Jet and Bengal bay CEF are affected by sea-land thermal differences,while Eastern Asian CEF is mostly influenced by sea surface temperature.Besides,the relationship between CEF and the heat source is osculation.The Bengal bay heat source and the intensity of CEF have the same tendency.The stronger Tibetan Plateau heat source is,the stronger Somali Jet and Eastern Asian CEF are.And when the warm pool in the western Pacific is stronger, Somali Jet and Bengal bay CEF are stronger.While the north of the warm pool in the western Pacific is stronger,the southern is weaker,Eastern Asian CEF is stronger.The intensity of the cross-equatorial flows at summer influence the water vapor between the northern and southern hemisphere,then change the rainfall there,and then change the Asian summer climate.