Westerly wind bursts and the diversity of ENSO in CCSM3 and CCSM4

Abstract

This study investigates the effect of parameterized westerly wind bursts (WWBs) on the diversity of El Niño-Southern Oscillation (ENSO) warm events, namely, eastern Pacific (EP) and central Pacific (CP) ENSO in Community Climate System Model version 3 (CCSM3) and version 4 (CCSM4). The parameterization includes the possibility of state-independent (SI) and state-dependent (SD) WWBs. The inclusion of WWBs enhances the overall tropical Pacific variability. This is accompanied by an increased in the so-called thermocline and advective feedback mechanisms. The SI WWB results present some model discrepancies, with CCSM3 (CCSM4) having enhanced CP (EP) ENSO variability. For the SD WWB case, both models show enhanced EP variability relative to CP variability. Key Points Central and eastern Pacific ENSO events are analyzed Westerly wind burst plays a role in ENSO variability Eastern Pacific ENSO events are strongly modified by westerly wind events ©2013. American Geophysical Union. All Rights Reserved.