An intrinsic low-frequency atmospheric mode of the Indonesian-Australian summer monsoon

IF 8.5 1区地球科学 Q1 METEOROLOGY & ATMOSPHERIC SCIENCES

npj Climate and Atmospheric Science Pub Date : 2024-10-08 DOI:10.1038/s41612-024-00792-1

Yu Liang, Shang-Ping Xie, Honghai Zhang

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Abstract

Deep convection in the Indo-Pacific warm pool is vital in driving global atmospheric overturning circulations. Year-to-year variations in the strength and location of warm pool precipitation can lead to significant local and downstream hydroclimatic impacts, including floods and droughts. While the El Niño-Southern Oscillation (ENSO) is recognized as a key factor in modulating interannual precipitation variations in this region, atmospheric internal variability is often as important. Here, through targeted atmospheric model experiments, we identify an intrinsic low-frequency atmospheric mode in the warm pool region during the austral summer, and show that its impact on seasonal rainfall is comparable to ENSO. This mode resembles the horizontal structure of the Madden-Julian Oscillation (MJO), and may play a role in initiating ENSO as stochastic forcing. We show that this mode is not merely an episodic manifestation of MJO events but primarily arises from barotropic energy conversion aided by positive feedback between convection and circulation.

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印度尼西亚-澳大利亚夏季季风的内在低频大气模式

印度洋-太平洋暖池内的深层对流对推动全球大气翻转环流至关重要。暖池降水强度和位置的逐年变化会对当地和下游的水文气候产生重大影响，包括洪水和干旱。虽然厄尔尼诺-南方涛动（ENSO）被认为是调节该地区年际降水量变化的关键因素，但大气内部变率往往也同样重要。在这里，我们通过有针对性的大气模式实验，确定了暖池区在澳大利亚夏季的一种内在低频大气模式，并表明它对季节性降水的影响与厄尔尼诺/南方涛动相当。这种模式类似于马登-朱利安涛动（MJO）的水平结构，可能在启动厄尔尼诺/南方涛动的随机强迫中发挥作用。我们的研究表明，这种模式不仅仅是 MJO 事件的偶发表现，它主要来自对流和环流之间正反馈作用下的气压能量转换。

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来源期刊

npj Climate and Atmospheric Science Earth and Planetary Sciences-Atmospheric Science

CiteScore

8.80

自引率

3.30%

发文量

审稿时长

21 weeks

期刊介绍： npj Climate and Atmospheric Science is an open-access journal encompassing the relevant physical, chemical, and biological aspects of atmospheric and climate science. The journal places particular emphasis on regional studies that unveil new insights into specific localities, including examinations of local atmospheric composition, such as aerosols. The range of topics covered by the journal includes climate dynamics, climate variability, weather and climate prediction, climate change, ocean dynamics, weather extremes, air pollution, atmospheric chemistry (including aerosols), the hydrological cycle, and atmosphere–ocean and atmosphere–land interactions. The journal welcomes studies employing a diverse array of methods, including numerical and statistical modeling, the development and application of in situ observational techniques, remote sensing, and the development or evaluation of new reanalyses.