Interannual And Interdecadal Variations Of The Atmospheric Heat Sources And Their Relationship With The Rainfall Over China

The global heat sources are calculated using the NCEP/NCAR dailyreanalysis data from 1958 to 2000. The seasonal, interannual andinterdecadal variations of the heat sources have been analyzed, and theirrelationship with the rainfall over China have been also investigated.Some new observed evidences have been found. The main results aresummarized as follows: The seasonal transition of the heat sources over the East Asianmonsoon area and the Indian monsoon area are of abruptness, which havea good consistence with the variations in the general circulations. Theannual range in the Asian monsoon area is most prominent in the world,and the second one is in the north to Australia. The variance of theinterannual scale heat sources is usually more remarkable than theinterdecadal one except in some area.The interannual variance of heat source has a co-belt spatial pattern,while the interdecadal variance has a zonally fluctuating distribution inthe tropics. On the interannual scale, the dominant anomaly patterns ofrainfall in summertime over China have very close relation with the heatsource anomalies over the warm pool area in the western Pacific and theeastern Tibetan Plateau especially. The floods/ droughts in the SouthernChina in July are remarkably related to the developing El Ni?o/La Ni?aevents. On interdecadal timescale, the rainfall over the southern area ofChina in May has a close linkage with the dipole pattern of heat sourceanomalies over the tropical Indian Ocean, while in June to August therainfalls over the Yangtze River basin and its vicinities are also relatedclosely with the heat sources variations in the tropical western Pacific.The rainfall anomalies in the Yangtze River basin and its vicinities inJuly and August have a good consistent variation. This rainfall anomalypersistency in July and August usually leads to the flood or droughtdisasters in the area mentioned above. These disaster events have linkagewith the heat source anomalies over the Pacific on ocean-wide scale. Theheat source anomalies over the central and eastern tropical Pacific andover the Tibetan Plateau area in the previous months, such as in May andJune, may provide an favor background to the flood or drought disastersin the Yangtze River basin and its vicinities.In the Indian-Pacific oceans, the dominant abnormal mode of seasurface temperature in boreal winter closely relates with the dominantabnormal mode in the followed spring and the abnormal modes inAsian-Australian monsoon area in summer and fall. The latent heat fluxand the sensible heat flux anomalies are very remarkable in the air-seainteraction processes in boreal winter and spring, and have importanteffects on the sea surface temperature and the low-level wind. However,the heat flux anomalies are weak generally in boreal summer. Theabnormal mode of the sea surface temperature in Asian-Australianmonsoon area in boreal summer may result to the rainfall anomalies overthe middle reaches of Yangtze River basin.