This paper presents an 8-year (2005–2012 inclusive) study of the marine aerosol distribution and variability over the Southern Indian Ocean, precisely in the areaa {10° S−40° S ; 50° E−110° E} which has been identified as one of the most pristine regions of the globe. A large dataset consisting of satellite data (POLDER, CALIOP), AERONET measurements at Saint-Denis (French Reunion Island) and model reanalysis (MACC), has been used. In spite of a positive bias of about 0.05 between the AOD (aerosol optical depth) given by POLDER and MACC on one hand and the AOD measured by AERONET on the other, consistent results for aerosol distribution and variability over the area considered have been obtained. First, aerosols are mainly confined below 2 km asl (above sea level) and are dominated by sea salt, especially in the center of the area of interest, with ≤ AOD 0. 1. This zone is the most pristine and is associated with the position of the Mascarene anticyclone. There, the direct radiative effect is assessed around − 9 W m^-2 at the top of the atmosphere and probability density functions of the AODs are leptokurtic lognormal functions without any significant seasonal variation. It is also suggested that the Madden-Jullian oscillation impacts sea salt emissions in the northern part of the area considered by modifying the state of the ocean surface. Finally, this area is surrounded in the northeast and the southwest by seasonal Australian and South African intrusions AOD > 0. 1); throughout the year, the ITCZ seems to limit continental contaminations from Asia. Due to the long period of time considered (almost a decade), this paper completes and strengthens results of studies based on observations performed during previous specific field campaigns.

中文翻译：

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原始南印度洋上的海洋气溶胶分布和变化

本文介绍了一项为期 8 年（包括 2005-2012 年）的南印度洋海洋气溶胶分布和变异性研究，恰好位于 {10° S−40° S ；50° E−110° E} 已被确定为地球上最原始的地区之一。已使用由卫星数据（POLDER、CALIOP）、圣但尼（留尼汪岛）的 AERONET 测量和模型再分析 (MACC) 组成的大型数据集。尽管一方面由 POLDER 和 MACC 给出的 AOD（气溶胶光学深度）与另一方面由 AERONET 测量的 AOD 之间存在大约 0.05 的正偏差，但已经获得了所考虑区域内气溶胶分布和可变性的一致结果。首先，气溶胶主要局限在 2 km asl 以下（海平面以上）并且以海盐为主，尤其是在感兴趣区域的中心，≤ AOD 0。 1. 该区是最原始的，与马斯卡林反气旋的位置有关。在那里，在大气顶部评估了大约 - 9 W m^-2 的直接辐射效应，并且 AOD 的概率密度函数是没有任何显着季节性变化的高峰态对数正态函数。还表明 Madden-Jullian 振荡影响了通过改变海洋表面状态所考虑区域北部的海盐排放。最后，该区域在东北和西南被澳大利亚和南非季节性侵入体包围，AOD > 0. 1)；全年，ITCZ 似乎限制了来自亚洲的大陆污染。由于考虑的时间很长（将近十年），