Role of the upper ocean structure in the response of ENSO-like SST variability to global warming

Sang Wook Yeh, Boris Dewitte, Bo Young Yim, Yign Noh

研究成果: Contribution to journalArticle査読

10 被引用数 (Scopus)

抄録

The response of El Niño and Southern Oscillation (ENSO)-like variability to global warming varies comparatively between the two different climate system models, i.e., the Meteorological Research Institute (MRI) and Geophysical Fluid Dynamics Laboratory (GFDL) Coupled General Circulation Models (CGCMs). Here, we examine the role of the simulated upper ocean temperature structure in the different sensitivities of the simulated ENSO variability in the models based on the different level of CO2 concentrations. In the MRI model, the sea surface temperature (SST) undergoes a rather drastic modification, namely a tendency toward a permanent El Niño-like state. This is associated with an enhanced stratification which results in greater ENSO amplitude for the MRI model. On the other hand, the ENSO simulated by GFDL model is hardly modified although the mean temperature in the near surface layer increases. In order to understand the associated mechanisms we carry out a vertical mode decomposition of the mean equatorial stratification and a simplified heat balance analysis using an intermediate tropical Pacific model tuned from the CGCM outputs. It is found that in the MRI model the increased stratification is associated with an enhancement of the zonal advective feedback and the non-linear advection. In the GFDL model, on the other hand, the thermocline variability and associated anomalous vertical advection are reduced in the eastern equatorial Pacific under global warming, which erodes the thermocline feedback and explains why the ENSO amplitude is reduced in a warmer climate in this model. It is suggested that change in stratification associated with global warming impacts the equatorial wave dynamics in a way that enhances the second baroclinic mode over the gravest one, which leads to the change in feedback processes in the CGCMs. Our results illustrate that the upper ocean vertical structure simulated in the CGCMs is a key parameter of the sensitivity of ENSO-like SST variability to global warming.

本文言語英語
ページ(範囲)355-369
ページ数15
ジャーナルClimate Dynamics
35
2
DOI
出版ステータス出版済み - 6 8 2010
外部発表はい

All Science Journal Classification (ASJC) codes

  • 大気科学

フィンガープリント

「Role of the upper ocean structure in the response of ENSO-like SST variability to global warming」の研究トピックを掘り下げます。これらがまとまってユニークなフィンガープリントを構成します。

引用スタイル