Quantifying the energetic feedbacks in ENSO
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Quantifying the energetic feedbacks in ENSO Han Huang1,2 · Yi Huang2 · Yongyun Hu1 Received: 14 November 2019 / Accepted: 1 October 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Energetic feedbacks play important roles during the El Niño-Southern Oscillation (ENSO). Here we conduct a thorough analysis of the radiative and non-radiative vertical fluxes and compare them to horizontal energy transport to provide a complete view of the energetics of ENSO. Our analyses affirm that cloud feedbacks are the most important radiative feedbacks, with cloud shortwave (SW) and longwave (LW) feedbacks dominating at the surface and in the atmosphere respectively. Oceanic energy transport dominates the oceanic heat content change in the developing phase and has significant effects on the sea surface temperature (SST) about 6 months earlier than vertical fluxes. Atmospheric horizontal energy transport is also important, acting to quickly remove the surplus of energy provided by the convergence of vertical energy fluxes in the atmosphere. The differential diabatic heating between the Central Pacific and the Warm Pool, induced by the latent heat release as well as LW radiation, strengthens the anomalous circulation and reinforces the Bjerknes positive feedback to strengthen the SST anomaly. This work reveals that the differential heating is more strongly correlated with the SST anomaly in the Central Pacific than the local SW negative feedback of clouds and supports the idea that the overall atmospheric effect is likely a positive feedback that acts to strengthen ENSO. Keywords Climate feedback · Energy budget · ENSO
1 Introduction The El Niño-Southern Oscillation (ENSO) is the dominant mode of interannual variability in the tropical climate system. The predominant characteristic of ENSO is associated with the SST anomalies in the Tropical Pacific which are accompanied by the movement of convective activities and together have the ability to significantly impact local climate and even climate variability in remote regions (Klein et al. 1999; Chiang and Sobel 2002; Trenberth et al. 2002; Liu and Alexander 2007). The transition between the ENSO warm phase (El Niño) and cold phase (La Niña) is also coupled with the weakening or strengthening of atmospheric Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00382-020-05469-y) contains supplementary material, which is available to authorized users. * Han Huang [email protected] 1
Department of Atmospheric and Oceanic Sciences, School of Physics, Peking University, Beijing, China
Department of Atmospheric and Oceanic Sciences, McGill University, Montreal, QC, Canada
2
circulations, such as the Walker circulation (Bjerknes 1966; Bayr et al. 2014). During the El Niño phase there are more convective activities in the Central Pacific which are accompanied by an increase of convective clouds and precipitation. With more clouds reflecting incoming solar radiation and more latent heat released by pre
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