Increasing Arabian dust activity and the Indian summer monsoon
Increasing Arabian dust activity and the Indian summer monsoon
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DOI：
10.5194/acp-15-8051-2015
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发表时间：
2015-07
影响因子：
6.3
通讯作者：
F. Solmon;V. S. Nair;M. Mallet
中科院分区：
文献类型：
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作者：
F. Solmon;V. S. Nair;M. Mallet
抽象的。在过去十年中，基于卫星和地面测量的气溶胶光学厚度观测显示，由于区域尘埃活动加剧，阿拉伯和阿拉伯海的气溶胶光学厚度显著增加。最近的研究还表明，西亚沙尘强迫可能在每周时间尺度上引起印度季风降水的积极响应。利用观测和包括板条-海洋和沙尘气溶胶方案在内的区域气候模式，本研究调查了6-7-8-9月阿拉伯沙尘活动增加与2000-2009年十年期间印度南部降水趋势之间可能的气候联系。气象再分析和AOD观测表明，观测到的印度南部沙尘活动的年代际增加和夏季降水趋势的同时加强都与JJAS在阿拉伯海上空的地面气压条件加深有关。在研究的第一部分，我们分析了该区域平均气候对沙尘辐射强迫的响应，特别是讨论了阿拉伯沙尘区和印度-巴基斯坦沙尘区的相对作用。在研究的第二部分，我们表明，只有在观测的基础上施加增加的沙尘排放趋势，模式才能显著提高再现区域动力模式和南印度降水趋势的能力。我们的结论是，尽管年际气候变率可能主要决定了2000-2009年十年间观测到的沙尘活动和降水增加的区域格局，但与之相关的沙尘辐射强迫反过来可能会引起关键的动力反馈，有助于加强印度南部地区的水汽辐合和JJAS降水。
Abstract. Over the past decade, aerosol optical depth (AOD) observations based on satellite and ground measurements have shown a significant increase over Arabia and the Arabian Sea, attributed to an intensification of regional dust activity. Recent studies have also suggested that west Asian dust forcing could induce a positive response of Indian monsoon precipitations on a weekly timescale. Using observations and a regional climate model including interactive slab-ocean and dust aerosol schemes, the present study investigates possible climatic links between the increasing June–July–August–September (JJAS) Arabian dust activity and precipitation trends over southern India during the 2000–2009 decade. Meteorological reanalysis and AOD observations suggest that the observed decadal increase of dust activity and a simultaneous intensification of summer precipitation trend over southern India are both linked to a deepening of JJAS surface pressure conditions over the Arabian Sea. In the first part of the study, we analyze the mean climate response to dust radiative forcing over the domain, discussing notably the relative role of Arabian vs. Indo-Pakistani dust regions. In the second part of the study, we show that the model skills in reproducing regional dynamical patterns and southern Indian precipitation trends are significantly improved only when an increasing dust emission trend is imposed on the basis of observations. We conclude that although interannual climate variability might primarily determine the observed regional pattern of increasing dust activity and precipitation during the 2000–2009 decade, the associated dust radiative forcing might in return induce a critical dynamical feedback contributing to enhancing regional moisture convergence and JJAS precipitations over southern India.