Assessment of haze transport via multi-scale pyramid optical flow method based on satellite-retrieved AOD image sequences

Abstract:

Quantitative assessment of interregional haze transport is of critical importance for developing optimal emission control policies and strategies. Previous studies on analyzing regional haze transport have been primarily based on meteorological and chemical transport models, which are subject to uncertainties associated with the assumptions and simplifications of models. In this study, an observation-based method is developed to analyze the inter-regional transport of haze using aerosol optical depth (AOD) image sequences with high temporal resolution derived by second generation geostationary satellite. Since these AOD image sequences could be regarded as video frames in computer vision, the multi-scale pyramid optical flow method, which is used to estimate the motion direction and motion speed for each pixel, is adopted to estimate aerosol transport in each geographic grid. It is demonstrated that the multi-scale pyramid optical flow method can describe the process of haze transport, provide qualitative and quantitative motion field of haze transport, and further calculate the aerosol transport flux. It is shown that the estimation of aerosol transport based on geostationary satellite observations could illustrate the process of atmospheric pollution transport with a higher temporal resolution than the Community Multiscale Air Quality (CMAQ) model. Besides, the aerosol transport flux estimated by remote sensing optical flow method is generally consistent with the aerosol transport flux simulated by CMAQ model with the correlation coefficient R over 0.8 on both longitude and latitude directions, which indicates the combination of satellite-based method with the traditional model-based method may further help to better understand the characteristics of haze interregional transport and its contribution to atmospheric pollution. Moreover, the methods in this study offer a new perspective to effectively and efficiently analyze haze transport at low cost, contributing significantly to the regional joint emission control and policy making.