Satellite-based estimates of ground-level nitrogen dioxide (NO 2 ) concentrations are useful for understanding links between air quality and health. A longstanding question has been why prior satellite-derived surface NO 2 concentrations are biased low with respect to ground-based measurements. In this work we demonstrate that these biases are due to both the coarse resolution of previous satellite NO 2 products and inaccuracies in vertical mixing assumptions used to convert satellite-observed tropospheric columns to surface concentrations. We develop an algorithm that now allows for different mixing assumptions to be used based on observed NO 2 conditions. We then apply this algorithm to observations from the TROPOMI satellite instrument, which has been providing NO 2 column observations at an unprecedented spatial resolution for over a year. This new product achieves estimates of ground-level NO 2 with greater accuracy...

中文翻译：

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推断适用于TROPOMI卫星仪器的精细空间分辨率下的地面二氧化氮浓度

基于卫星的地面二氧化氮（NO 2）浓度估算值有助于理解空气质量与健康之间的联系。一个长期存在的问题是，相对于地面测量，为什么以前的卫星衍生的表面NO 2浓度偏低。在这项工作中，我们证明了这些偏差是由于以前的卫星NO 2产物的分辨率较粗，而且是由于将卫星观测的对流层柱转换为地表浓度的垂直混合假设的不准确所致。我们开发了一种算法，该算法现在允许根据观察到的NO 2条件使用不同的混合假设。然后，我们将此算法应用于TROPOMI卫星仪器的观测结果，该仪器一年多来一直以空前的空间分辨率提供NO 2列观测结果。