High Resolution Aerosol Optical Depth Retrieval Over Urban Areas Based on GaoFen-1 and GaoFen-6 Synergistic Observations
Abstract
The satellite-based aerosol optical depth (AOD), which can provide spatially continuous observation of aerosol loadings, is widely adopted in estimating environmental quality and evaluating its risk for human health. However, current satellite-retrieved AOD products with relatively coarse spatial resolution (1 km) fail to capture the detailed spatial variations of air pollution or its relationship with landscapes over populous urban areas. Existing studies have tried to address this deficiency by retrieving high-resolution AOD using Landsat images, whose long revisit period (16 days nominally), however, largely limits its applications to urban air pollution research. To achieve both high spatial resolution and desired revisit period, we develop a new AOD retrieval algorithm to obtain 160 m resolution AOD in Beijing with temporal resolution of 1~2 days, based on synergistic observations from two sets of wide-field-of-view (WFV) sensors onboard the GaoFen-1 and GaoFen-6 satellites. In this algorithm, the geometric accuracy and radiometric consistency of all WFV sensors are ensured by conducting further precise geometric correction and radiometric cross-calibration against Landsat 8 Operational Land Imager. Moreover, in order to address the significant bidirectional reflectance characteristics caused by high spatial resolution observation over complex urban areas, multiyear seasonal Rahman BRDF models are constructed using simulated annealing algorithm, based on clear-sky WFV images after Rayleigh scattering correction, gas absorption correction, and background aerosol correction. The validation results indicate that the retrieved WFV AOD exhibits good agreement with the ground-based AERONET AOD with R2 reaching up to 0.8 and nearly 70% of the matchups falling within the expected error envelop. In addition, the WFV AOD could provide more aerosol loading details and illustrate finer spatially resolved aerosol variations over urban areas, when compared with the MODIS AOD products. Such an improvement from the 160 m WFV AOD, combined with its near-daily revisit, demonstrates its huge potentials in supporting further studies of air pollution emission management and human exposure at extra-fine spatial scales over urban areas.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2021
- Bibcode:
- 2021AGUFM.A12C..01Z