Abstract Aerosol optical properties have been analyzed to investigate seasonal and regional variability of aerosols and to classify their key types over the Middle East region during the period 2001–2019. The collection 6.1 MODIS aerosol products are used, including daily values of aerosol optical depth (AOD) and the Angstrom exponent (AE) data. The MODIS aerosol retrieval has been verified using measurements from ten ground-based sunphotometers of the AErosol RObotic NETwork (AERONET). Overall, a good agreement between the two datasets has been found. Nevertheless, an overestimation of the MODIS retrievals is found in most of the regions. Seasonal comparison reveals that aerosol loading ranges between 0 and 0.7, with a distinct geographical variability. The highest value of AOD is found over the Arabian Peninsula especially during warm seasons. The second maximum value of AOD is located over an area stretching from southeastern Iran to western Pakistan, with higher values during summer. The lowest AOD values are found over countries in the northern part of the studied region, including Turkmenistan, Uzbekistan, Kazakhstan, Armenia and Georgia, as well as some parts of Turkey. Regions with the highest aerosol loads are accompanied with the lowest AE values. Coarse marine particles are dominant in coastal regions in southern Iran across the Persian Gulf. There is an increasing trend of AOD values, reaching to 0.05 per decade over the Arabian Peninsula and the northern coast of the Caspian Sea in all seasons, while negative trends are found in Pakistan, south Afghanistan, west coast of the Black Sea and northeast of Africa. During cold seasons, AOD does not vary as in warm seasons. Aerosols have been classified using the critical values for AOD and AE. Results show the dominance of mixed type aerosols in all seasons. In spring and summer, desert dust is the second-highest contributor to aerosol composition, followed by urban aerosols. Maritime-like aerosols transported from the Caspian Sea and the Aral Sea are presented mostly during autumn. Uzbekistan, Turkmenistan and western parts of Kazakhstan commonly have a relatively clean atmosphere during the whole year, except for episodic dust storms in summer. Smoke has a small undetectable contribution to the studied region.

中文翻译：

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使用卫星衍生的大气光学数据集对中东关键类型的气溶胶特性、趋势和分类

摘要 对气溶胶光学特性进行了分析，以研究气溶胶的季节性和区域变化，并对 2001-2019 年中东地区气溶胶的关键类型进行分类。使用集合 6.1 MODIS 气溶胶产品，包括气溶胶光学深度 (AOD) 和埃指数 (AE) 数据的每日值。MODIS 气溶胶反演已使用来自 AErosol 机器人网络 (AERONET) 的十个地面太阳光度计的测量值进行了验证。总体而言，已发现两个数据集之间具有良好的一致性。然而，在大多数地区发现对 MODIS 反演的高估。季节性比较显示气溶胶载荷范围在 0 到 0.7 之间，具有明显的地理变异性。AOD 的最高值出现在阿拉伯半岛，尤其是在温暖的季节。AOD 的第二个最大值位于从伊朗东南部到巴基斯坦西部的区域，夏季数值较高。最低 AOD 值出现在研究区域北部的国家，包括土库曼斯坦、乌兹别克斯坦、哈萨克斯坦、亚美尼亚和格鲁吉亚，以及土耳其的一些地区。具有最高气溶胶载荷的区域伴随着最低的 AE 值。粗大的海洋颗粒在伊朗南部横跨波斯湾的沿海地区占主导地位。AOD 值呈上升趋势，在阿拉伯半岛和里海北部海岸所有季节均达到每十年 0.05，而在巴基斯坦、阿富汗南部、黑海西海岸和东北部地区则呈负趋势。非洲。在寒冷季节，AOD 与温暖季节不同。气溶胶已使用 AOD 和 AE 的临界值进行分类。结果显示混合型气溶胶在所有季节中占主导地位。在春季和夏季，沙漠尘埃是气溶胶成分的第二大贡献者，其次是城市气溶胶。从里海和咸海输送来的类似海洋的气溶胶主要在秋季出现。乌兹别克斯坦、土库曼斯坦和哈萨克斯坦西部地区除夏季偶发沙尘暴外，全年大气相对清洁。烟雾对研究区域的贡献很小，无法检测到。从里海和咸海输送来的类似海洋的气溶胶主要在秋季出现。乌兹别克斯坦、土库曼斯坦和哈萨克斯坦西部地区除夏季偶发沙尘暴外，全年大气相对清洁。烟雾对研究区域的贡献很小，无法检测到。从里海和咸海输送来的类似海洋的气溶胶主要在秋季出现。乌兹别克斯坦、土库曼斯坦和哈萨克斯坦西部地区除夏季偶发沙尘暴外，全年大气相对清洁。烟雾对研究区域的贡献很小，无法检测到。