THE KEY OCEANIC REGIONS AFFECTING INTERANNUAL VARIATION OF ONSET DATE OF SCSSM AND THEIR PRELIMINARY MECHANISMS
GU De-jun
JI Zhong-ping
LIN Ai-lan
Abstract：The origin of SSTA of key oceanic regions affecting the interannual variation of onset date of South China Sea summer monsoon and possible mechanisms are studied using Lanczos filter,correlation analysis,regression analysis,composite analysis and cross-validation with NCEP/NCAR reanalysis dataset and ERSST dataset from 1958 to 2011.The results show that the previous winter tropical southwest Indian Ocean and tropical northwest Pacific are key oceanic regions affecting the interannual variation of South China Sea summer monsoon onset date.The anomalous warming of winter tropical southwest Indian Ocean (tropical northwest Pacific) is triggered by E1 Ni(n)o early onset (planetary east-west circulation induced by heating of strong Indian summer monsoon),and maintained by local air-sea interaction positive feedback process in tropical Indian Ocean (tropical northwest Pacific) until the spring.The winter anticyclonic (cyclonic) circulation over tropical northwest Pacific and local air-sea interaction positive feedback process in tropical Indian Ocean (tropical northwest Pacific) make SSTA in tropical Indian Ocean (tropical northwest Pacific) maintain until the spring.The spring low-level easterly jet (anomalous westerly) responding to warm SSTA in north Indian Ocean (tropical northwest Pacific) gradually enhances and moves northward to 10 °N.The anomalous anticyclonic (cyclonic) circulation over South China Sea and tropical northwest Pacific induces late (early) onset of South China Sea summer monsoon.
Keywords：onset of South China Sea summer monsooninterannual variationkey oceanic regionmechanismtropical southwest Indian Oceantropical northwest Pacific
Publication Date：2018-01-01
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：11( 1-11 )