The southwestern Iran is one of the regions that are most prone to dust events. The objective of this study is the analysis of the spatial and temporal distributions of dust deposition rate as a key factor for finding the relative impact of the dust. First, the monthly mean aerosol optical thickness (AOT) from Moderate Resolution Imaging Spectroradiometer (MODIS) was analyzed and compared with the dust amount variations from ground deposition rate (GDR), and the results were further used to investigate the spatial and temporal distributions of dust events in southwestern Iran for the period between 2014 and 2015. Moving air mass trajectories, using the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model, were proven to be a discriminator of their local and regional origin. The results from GDR analysis produced a correlation coefficient between dust event history and deposition rates at dust magnitudes of >0.93 that is meaningful at the 95% confidence level. Furthermore, the deposition rates varied from 3 g/m2 per month in summer to 10 g/m2 per month in spring and gave insight into the transport direction of the dust. Within the same time series, AOT correspondences with MODIS on Terra in four aerosol thickness layers (clean, thin, thick, and strong thick) were shown in relation to each other. The deepest mixed layers were observed in spring and summer with a thickness of approximately 3500 m above ground level in the study area. Investigations of ground-based observations were correlated with the same variations for each aerosol thickness layer from MODIS images and they can be applied to discriminate layers of aeolian dust from layers of other aerosols. Together, dust distribution plots from AOT participated to enhance mass calculations and estimation deposition rates from the thick and strong thick aerosol thickness layers using the results from GDR. Despite all the advances of AOT, under certain circumstances, ground-based observations are better able to represent aerosol conditions over the study area, which were tested in southwestern Iran, even though the low number of observations is a commonly acknowledged drawback of GDR.

中文翻译：

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伊朗西南部沙尘沉积速率和气溶胶光学厚度的时空梯度

伊朗西南部是最容易发生沙尘事件的地区之一。本研究的目的是分析沙尘沉积率的空间和时间分布，作为发现沙尘相对影响的关键因素。首先，分析了中分辨率成像光谱仪 (MODIS) 的月平均气溶胶光学厚度 (AOT) 并与地面沉积率 (GDR) 的沙尘量变化进行了比较，并将结果进一步用于研究2014 年至 2015 年期间伊朗西南部的沙尘事件。使用混合单粒子拉格朗日综合轨迹 (HYSPLIT) 模型的移动气团轨迹被证明是其当地和区域起源的鉴别器。GDR 分析的结果在沙尘量级 >0.93 时产生了沙尘事件历史和沉积率之间的相关系数，这在 95% 的置信水平下有意义。此外，沉积率从夏季的每月 3 g/m2 到春季的每月 10 g/m2 不等，并且可以深入了解灰尘的传输方向。在同一时间序列中，AOT 与 Terra 上的 MODIS 在四个气溶胶厚度层（干净、薄、厚和强厚）中的对应关系相互显示。研究区春季和夏季观测到最深的混合层，厚度约为地表以上3500 m。对地面观测的调查与 MODIS 图像中每个气溶胶厚度层的相同变化相关，它们可用于区分风尘层和其他气溶胶层。AOT 的尘埃分布图一起参与使用 GDR 的结果来增强厚厚和厚厚气溶胶厚度层的质量计算和估计沉积率。尽管 AOT 取得了所有进步，但在某些情况下，地面观测能够更好地代表研究区域的气溶胶条件，这些条件在伊朗西南部进行了测试，尽管观测数量少是 GDR 的一个普遍公认的缺点。来自 AOT 的尘埃分布图参与了使用 GDR 的结果来增强质量计算和估算厚厚和厚厚气溶胶厚度层的沉积率。尽管 AOT 取得了所有进步，但在某些情况下，地面观测能够更好地代表研究区域的气溶胶条件，这些条件在伊朗西南部进行了测试，尽管观测数量少是 GDR 的一个普遍公认的缺点。来自 AOT 的尘埃分布图参与了使用 GDR 的结果来增强质量计算和估算厚厚和厚厚气溶胶厚度层的沉积率。尽管 AOT 取得了所有进步，但在某些情况下，地面观测能够更好地代表研究区域的气溶胶条件，这些条件在伊朗西南部进行了测试，尽管观测数量少是 GDR 的一个普遍公认的缺点。