Relative Contributions of Sea Surface Temperature and Atmospheric Nonlinearities to ENSO Asymmetrical Rainfall Response

Author:

Srinivas G.1,Vialard J.1,Lengaigne M.2,Izumo T.3,Guilyardi E.14

Affiliation:

1. a LOCEAN-IPSL, Sorbonne Université (UPMC, Univ Paris 06) CNRS-IRD-MNHN, Paris, France

2. b MARBEC, University of Montpellier, CNRS, IFREMER, IRD Sète, France

3. c EIO, Ifremer, ILM, UPF, IRD, Ifremer Tahiti, France

4. d NCAS-Climate, University of Reading, Reading, United Kingdom

Abstract

Abstract Here, we investigate the relative roles of atmospheric nonlinearities and asymmetrical sea surface temperature (SST) forcing in the El Niño–Southern Oscillation (ENSO) asymmetrical rainfall response. Applying a vertically integrated water vapor budget to the ERA5 reanalysis leads to a simple analytical equation for precipitation anomalies. This formulation reveals that ENSO rainfall anomalies are dominated by the linear component of the dynamical term (i.e., the anomalous moisture convergence due to the effect of circulation anomalies on climatological humidity). Nonlinearities in this term and the linear thermodynamical term (i.e., the effect of climatological circulation on humidity anomalies) both strengthen central Pacific rainfall anomalies for both ENSO phases. In contrast, the nonlinear term associated with the effect of anomalous divergence on anomalous moisture (i.e., the mixed term) weakens La Niña dry and strengthens El Niño wet anomalies, in particular during extreme El Niño events when it contributes to about 40% of the eastern Pacific wet anomalies. Overall, atmospheric nonlinearities directly account for ∼70% of the positively skewed ENSO rainfall distribution east of the date line, and ∼50% of the negatively skewed rainfall distribution in the western Pacific. The remaining ENSO rainfall asymmetries are attributable to the asymmetrical ENSO SST pattern. This asymmetrical SST pattern also has contributions from atmospheric nonlinearities through the Bjerknes feedback loop, in addition to those from oceanic nonlinearities. Our estimates are thus likely a lower bound of the contribution of atmospheric nonlinearities to the overall ENSO rainfall asymmetry.

Funder

Agence Nationale de la Recherche

Publisher

American Meteorological Society

Subject

Atmospheric Science

Reference140 articles.

1. The March 1997 westerly wind event and the onset of the 1997/98 El Niño: Understanding the role of the atmospheric response;Lengaigne;J. Climate,2004

2. The asymmetric influence of ocean heat content on ENSO predictability in the CNRM-CM5 coupled general circulation model;Planton;J. Climate,2022

3. Atmospheric convergence feedback in a simple model for El Niño;Zebiak;Mon. Wea. Rev.,1986

4. ENSO Atmospheric Teleconnections

5. Ensemble-mean dynamics of the ENSO recharge oscillator under state-dependent stochastic forcing;Jin;Geophys. Res. Lett.,2007

Cited by 7 articles. 订阅此论文施引文献 订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献

同舟云学术

1.学者识别学者识别

2.学术分析学术分析

3.人才评估人才评估

"同舟云学术"是以全球学者为主线,采集、加工和组织学术论文而形成的新型学术文献查询和分析系统,可以对全球学者进行文献检索和人才价值评估。用户可以通过关注某些学科领域的顶尖人物而持续追踪该领域的学科进展和研究前沿。经过近期的数据扩容,当前同舟云学术共收录了国内外主流学术期刊6万余种,收集的期刊论文及会议论文总量共计约1.5亿篇,并以每天添加12000余篇中外论文的速度递增。我们也可以为用户提供个性化、定制化的学者数据。欢迎来电咨询!咨询电话:010-8811{复制后删除}0370

www.globalauthorid.com

TOP

Copyright © 2019-2024 北京同舟云网络信息技术有限公司
京公网安备11010802033243号  京ICP备18003416号-3