Diurnal Variation of Outgoing Longwave Radiation in the Vicinity of the South China Sea: Effect of Intraseasonal Oscillation

Publisher Website
Google Scholar
Abstract
It has been observed in numerous studies that (a) tropical cumulus convection undergoes a distinct diurnal variation, and (b) this diurnal variation exhibits a significant contrast between land and sea. In addition, tropical cumulus convection, particularly over the Asian monsoon region and the maritime continent, is greatly modulated by the eastward propagation of the global intraseasonal (30–60-day) oscillation (ISO). Conceivably, the diurnal variation of tropical cumulus convection is affected by this global ISO mode. In order to answer this question, the equivalent blackbody temperature TBB observed by the Japanese geostationary meteorological satellite over the South China Sea and its vicinity were analyzed. The major findings in this study are as follows. 1) Centers of the TBB diurnal cycles during the northern summers are located over land around the South China Sea region north of the equator, while those in the northern winter exist over land around the southern part of this sea. 2) In the northern summer, the TBB diurnal cycle is suppressed over land and enhanced over the open sea during the active ISO phase. This land–sea contrast of the TBB diurnal cycle is reversed during the inactive ISO phase. 3) During the northern winter, changes in the TBB diurnal cycle between the active and inactive ISO phases become less pronounced because there is less open sea in the southern South China Sea. 4) The eastward propagation of the global ISO mode does not generally induce a significant phase change in the TBB diurnal cycle.

This publication has 0 references indexed in Scilit: