Satellite remote sensing is very important to obtain a variety of cloud properties. However, the data quality from satellites varies with different satellite characteristics. From December 2015 to January 2016, ground...Satellite remote sensing is very important to obtain a variety of cloud properties. However, the data quality from satellites varies with different satellite characteristics. From December 2015 to January 2016, ground-based air quality index （AQI） data showed severe haze events occurred successively in eastern China, particularly in the Beijing-Tianjin-Hebei region. During those days, a red alert （the most serious level）, orange alert （the second-highest level）, and yellow alert （the third-highest level） for haze, were issued in Beijing. Cloud detection from four sensors onboard the ＇A-Train＇satellite constellation were compared for two severe haze episodes, on 21 and 30 December 2015 respectively. Results showed that the MODIS sensor onboard the Aqua satellite misclassified aerosol as cloud, while the other three sensors-AIRS onboard Aqua, the cloud profiling radar onboard CloudSat, and CALIOP onboard CALIPSO-did not observe cloud over the same location. Through the high-AQI haze region in the CALIPSO and CloudSat orbit track, MODIS marked cloud close to the surface, while the MODIS true-color image and CALIOP observed an aerosol layer over the same location, suggesting MODIS falsely observed cloud there. Over the haze region in eastern China, MODIS observed 36% on average greater cloud fraction than AIRS, suggesting haze pollution induces a greater MODIS cloud amount.展开更多
基金supported by the National Natural Science Foundation of China[grant number 41590874]and[grant number41590875]
文摘Satellite remote sensing is very important to obtain a variety of cloud properties. However, the data quality from satellites varies with different satellite characteristics. From December 2015 to January 2016, ground-based air quality index （AQI） data showed severe haze events occurred successively in eastern China, particularly in the Beijing-Tianjin-Hebei region. During those days, a red alert （the most serious level）, orange alert （the second-highest level）, and yellow alert （the third-highest level） for haze, were issued in Beijing. Cloud detection from four sensors onboard the ＇A-Train＇satellite constellation were compared for two severe haze episodes, on 21 and 30 December 2015 respectively. Results showed that the MODIS sensor onboard the Aqua satellite misclassified aerosol as cloud, while the other three sensors-AIRS onboard Aqua, the cloud profiling radar onboard CloudSat, and CALIOP onboard CALIPSO-did not observe cloud over the same location. Through the high-AQI haze region in the CALIPSO and CloudSat orbit track, MODIS marked cloud close to the surface, while the MODIS true-color image and CALIOP observed an aerosol layer over the same location, suggesting MODIS falsely observed cloud there. Over the haze region in eastern China, MODIS observed 36% on average greater cloud fraction than AIRS, suggesting haze pollution induces a greater MODIS cloud amount.
