INTERDECADAL CHANGE OF DIABATIC FORCING OVER KEY REGION OF THE MARITIME CONTINENT AND ITS POSSIBLE RELATIONS WITH EAST ASIAN SUMMER MONSOON ANOMALIES

doi:10.16032/j.issn.1004-4965.2017.01.003

Abstract：Maritime continent is an important region where the tropical Pacific and Indian Ocean interact with each other via "the atmospheric bridge" and also a key region where the Asian monsoons interact with the Australian monsoons.Using the NCEP/NCAR and CMAP monthly mean reanalysis over the period of 1979-2012,the interdecadal variations of diabatic forcing over key region of the Maritime Continent and its possible relations with East Asian summer monsoon anomalies have been investigated in the present paper.Our results show that climate variations in the Maritime Continent are particularly strong in the area 95～145 °E,10 °S～10 °N.This area is hence defined as the key area of the Maritime Continent (i.e.,KMC area).Without the input of latent heat release in the atmosphere,distinct interdecadal change of diabatic heating are found to exist from 1979 to 2012 in the KMC area;it intensified before the 1980s and peaked in the late 1980s and weakened after this period.By analyzing different components of the diabatic heating in the KMC area,it is found that surface latent heat flux and net long-wave radiation in the atmosphere are the dominant components.When the anomalies of diabatic heating are negative,there will be more precipitation on land,less precipitation over sea,and more rainfall around the equator,which is in correspondence with a convergence center around the equator in the KMC area.In the meridional-vertical section averaged over 115 ～120 °E,well-defined vertical circulation anomalies are observed with its ascending branches over KMC and the area near 30 °N respectively and the descending branch over the South China Sea.Water vapor transports from the Bay of Bengal and South China Sea area to the east of China to benefit the positive precipitation anomalies.This vertical circulation plays a crucial role in linking the diabatic heating over the KMC region and East Asian summer monsoon variations on interdecadal time-scale.