Abstract：
Aerosol optical depth (AOD) serves as a crucial indicator for assessing regional air quality. To address regional and urban pollution issues, there is a requirement for high-resolution AOD products, as the existing data is of very coarse resolution. To address this issue, we retrieved high-resolution AOD over Kanpur (26.4499°N, 80.3319°E), located in the Indo-Gangetic Plain (IGP) region using Landsat 8 imageries and implemented the algorithm SEMARA, which combines SARA (Simplified Aerosol Retrieval Algorithm) and SREM (Simplified and Robust Surface Reflectance Estimation). Our approach leveraged the green band of the Landsat 8, resulting in an impressive spatial resolution of 30 m of AOD and rigorously validated with available AERONET observations. The retrieved AOD is in good agreement with high correlation coefficients (r) of 0.997, a low root mean squared error of 0.035, and root mean bias of - 4.91%. We evaluated the retrieved AOD with downscaled MODIS (MCD19A2) AOD products across various land classes for cropped and harvested period of agriculture cycle over the study region. It is noticed that over the built-up region of Kanpur, the SEMARA algorithm exhibits a stronger correlation with the MODIS AOD product compared to vegetation, barren areas and water bodies. The SEMARA approach proved to be more effective for AOD retrieval over the barren and built-up land categories for harvested period compared with the cropping period. This study offers a first comparative examination of SEMARA-retrieved high-resolution AOD and MODIS AOD product over a station of IGP.
摘要：
气溶胶光学深度（AOD）是评估区域空气质量的重要指标。解决区域和城市污染问题,对高分辨率AOD产品有要求，因为现有数据的分辨率非常粗略。为了解决这个问题，我们在坎普尔（26.4499°N，80.3319°E),使用Landsat8图像位于印度恒河平原（IGP）区域，并实现了算法SEMARA，它结合了SARA（简化的气溶胶检索算法）和SREM（简化和鲁棒的表面反射率估计）。我们的方法利用了Landsat8的绿色带，产生了令人印象深刻的30mAOD空间分辨率，并通过可用的AERONET观测进行了严格验证。检索到的AOD与0.997的高相关系数（r），0.035的低均方根误差和-4.91％的均方根偏差非常吻合。我们在研究区域的农业周期的作物和收割期，评估了在不同土地类别中使用缩减规模的MODIS（MCD19A2）AOD产品检索到的AOD。值得注意的是，在坎普尔的建筑区域，与植被相比，SEMRA算法与MODISAOD产品具有更强的相关性，贫瘠的地区和水体。与耕种期相比，SEMARA方法被证明在收割期的贫瘠和建成区土地类别上的AOD检索更有效。这项研究在IGP站上首次对SEMRA检索的高分辨率AOD和MODISAOD产品进行了比较检查。
