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Seasonal Cycle of Background in the Tropical Pacific as a Cause of ENSO Spring Persistence Barrier
Author(s) -
Jin Yishuai,
Liu Zhengyu,
Lu Zhengyao,
He Chengfei
Publication year - 2019
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2019gl085205
Subject(s) - thermocline , el niño southern oscillation , climatology , spring (device) , environmental science , persistence (discontinuity) , predictability , southern oscillation , oscillation (cell signaling) , atmospheric sciences , geology , physics , biology , mathematics , statistics , genetics , geotechnical engineering , thermodynamics
Statistical model results suggest that the declining growth rate from autumn to spring is the key to cause El Niño‐Southern Oscillation (ENSO) spring persistence barrier (SPB). Using a dynamical approach, we develop the physical mechanisms responsible for ENSO SPB in the framework of recharge oscillator by adding a seasonally varying Bjerknes (BJ) stability index and linking it with ENSO growth rate. By decomposing BJ index, it is indicated that seasonal thermodynamic damping and thermocline positive feedback play an important role in determining the ENSO SPB. We further show that the increasing/decreasing upper‐level cloud/low‐level cloud and the deepening thermocline from autumn to spring are the main factors to control the SPB of ENSO. Our proposed mechanisms also have useful implications for the understanding of ENSO prediction.