Increasing Influence of Indian Ocean Dipole on Precipitation Over Central Equatorial Africa
Increasing Influence of Indian Ocean Dipole on Precipitation Over Central Equatorial Africa
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DOI：
10.1029/2020gl092370
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发表时间：
2021-04
影响因子：
5.2
通讯作者：
Yan Jiang;Liming Zhou;P. Roundy;W. Hua;A. Raghavendra
中科院分区：
文献类型：
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作者：
Yan Jiang;Liming Zhou;P. Roundy;W. Hua;A. Raghavendra
使用观测降雨数据集，我们确定了1981-2019年9月至12月（SOND）期间赤道非洲中部（CEA）降水与印度洋偶极子（IOD）之间的正相关性。正IOD事件期间降水量显著增加。降水的增强主要是由于降水频率增加，并在10月达到最大值。IOD通过改变热带印度洋上空的步行者环流和CEA上空对流层中层的湿度来影响降雨。Madden-Julian Oscillation（MJO）活动与IOD协变，调制非洲东部急流，这对CEA上空的对流发展至关重要。SOND降雨量在过去二十年中有所增加，这与IOD指数和IOD与降雨量之间的相关性的增加是同步的。IOD一致的降雨量变化可能是CEA南部和东部降雨趋势的主要原因。
Using observational rainfall datasets, we identify a positive correlation between precipitation over Central Equatorial Africa (CEA) and the Indian Ocean Dipole (IOD) during September‐December (SOND) for the period 1981–2019. Rainfall amount significantly increases during positive IOD events. The enhancement in precipitation is primarily attributed to increased rainfall frequency and reaches the maximum in October. IOD impacts rainfall via modifying the Walker circulation over the tropical Indian Ocean and moisture in the middle troposphere over CEA. The Madden‐Julian Oscillation (MJO) activity covaries with IOD to modulate the African Easterly Jet, which is critical to convection development over CEA. SOND rainfall has increased for the last two decades, which is concurrent with increases in both the IOD index and the correlation between IOD and rainfall. The IOD‐congruent rainfall changes potentially account for much of rainfall trends in southern and eastern CEA.