Sea Surface Temperature-Convection Relationship in Tropical Oceans with Special Emphasis to Intraseasonal Variability of Indian Summer Monsoon

Content Provider	CUSAT-Thesis
Advisor	Dr.Babu, C A
Researcher	Sabin, T. P.
Abstract	The SST convection relation over tropical ocean and its impact on the South Asian monsoonis the first part of this thesis. Understanding the complicated relation between SSTand convection is important for better prediction of the variability of the Indian monsoonin subseasonal, seasonal, interannual, and longer time scales. Improved globaldata sets from satellite scatterometer observations of SST, precipitation and refined reanalysisof global wind fields have made it possible to do a comprehensive study ofthe SST convection relation. Interaction of the monsoon and Indian ocean has beendiscussed. A coupled feedback process between SST and the Active-Break cycle of theAsian summer monsoon is a central theme of the thesis. The relation between SST andconvection is very important in the field of numerical modeling of tropical rainfall. It iswell known that models generally do very well simulating rainfall in areas of tropicalconvergence zones but are found unable to do satisfactory simulation in the monsoonareas. Thus in this study we critically examined the different mechanisms of generationof deep convection over these two distinct regions.The study reported in chapter 3 has shown that SST - convection relation over thewarm pool regions of Indian and west Pacific oceans (monsoon areas) is in such a waythat convection increases with SST in the SST range 26-29 C and for SST higher than29-30 C convection decreases with increase of SST (it is called Waliser type). It is found that convection is induced in areas with SST gradients in the warm pool areas ofIndian and west Pacific oceans. Once deep convection is initiated in the south of thewarmest region of warm pool, the deep tropospheric heating by the latent heat releasedin the convective clouds produces strong low level wind fields (Low level Jet - LLJ)on the equatorward side of the warm pool and both the convection and wind are foundto grow through a positive feedback process. Thus SST through its gradient acts onlyas an initiator of convection. The central region of the warm pool has very small SSTgradients and large values of convection are associated with the cyclonic vorticity of theLLJ in the atmospheric boundary layer. The conditionally unstable atmosphere in thetropics is favorable for the production of deep convective clouds.
File Format	PDF
Language	English
Publisher Institution	Cochin University of Science and Technology
Access Restriction	Open
Subject Keyword	Sea surface temperature (SST) Tropical Oceans Intraseasonal Variability Indian Summer Monsoon Low Level Jetstream (LLJ) Atmospheric Science
Content Type	Text
Educational Degree	Doctor of Philosophy (Ph.D.)
Resource Type	Thesis