The asymmetric influence of the positive and negative IOD events on China's rainfall.
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ABSTRACT: Rainfall anomalies over southern China are found to be asymmetricly influenced by the Indian Ocean Dipole (IOD), with a far stronger influence from positive IOD (pIOD) events. A greater convection anomaly and an equivalent-barotropic Rossby wave train response occurs during pIOD events than during negative IOD (nIOD) events. Over the Bay of Bengal (BOB) and South China Sea (SCS), an associated low-level anomalous anticyclone strengthens the southwesterlies during boreal fall (September, October and November, SON), when a pIOD matures. The increased moisture flux gives rise to the anomalously high rainfall over southern China. During its developing phase (boreal summer, June, July, and August, JJA), the influence of a pIOD event on the contemporaneous rainfall over southern China is weak, but a JJA pIOD index is highly correlated with fall rainfall. Therefore, this index can serve as a potential predictor for variations of boreal fall rainfall over southern China.
SUBMITTER: Qiu Y
PROVIDER: S-EPMC4021319 | biostudies-other | 2014
REPOSITORIES: biostudies-other
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