Open AccessLinking the Pacific Meridional Mode to ENSO: Coupled Model Analysis
Author(s) -
Li Zhang,
Ping Chang,
Ji Luo
Publication year - 2009
Publication title -
journal of climate
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.315
H-Index - 287
eISSN - 1520-0442
pISSN - 0894-8755
DOI - 10.1175/2008jcli2473.1
Subject(s) - intertropical convergence zone , climatology , zonal and meridional , forcing (mathematics) , boreal , geology , el niño southern oscillation , atmosphere (unit) , climate model , atmospheric sciences , walker circulation , oscillation (cell signaling) , equator , latitude , environmental science , oceanography , climate change , physics , meteorology , precipitation , paleontology , geodesy , biology , genetics
The occurrence of a boreal spring phenomenon referred to as the Pacific meridional model (MM) is shown to be intimately linked to the development of El Niño–Southern Oscillation (ENSO) in a long simulation of a coupled model. The MM, characterized by an anomalous north–south SST gradient and anomalous surface circulation in the northeasterly trade regime with maximum variance in boreal spring, is shown to be inherent to thermodynamic ocean–atmosphere coupling in the intertropical convergence zone (ITCZ) latitude, and the MM existence is independent of ENSO. The thermodynamic coupling enhances the persistence of the anomalous winds in the deep tropics, forcing energetic equatorially trapped oceanic waves to occur in the central western Pacific, which in turn initiate an ENSO event. The majority of ENSO events in both nature and the coupled model are preceded by MM events.