Seasonal Cycle of Background in the Tropical Pacific as a Cause of ENSO Spring Persistence Barrier

Summary, in English

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.

• Author: Yishuai Jin; Zhengyu Liu; Zhengyao Lu; Chengfei He
• Department/s: Dept of Physical Geography and Ecosystem Science; MERGE: ModElling the Regional and Global Earth system
• Publishing year: 2019-11-12
• Language: English
• Pages: 13371-13378
• Publication/Series: Geophysical Research Letters
• Volume: 46
• Issue: 22
• Links: http://dx.doi.org/10.1029/2019GL085205
• Document type: Journal article
• Publisher: American Geophysical Union (AGU)
• Topic: Meteorology and Atmospheric Sciences
• Keywords: Bjerknes stability index; cloud; El Niño-Southern Oscillation; seasonal persistence barrier; thermocline
• Status: Published
• ISBN/ISSN/Other: ISSN: 0094-8276