Surface shortwave radiation(SSR)plays an important role in global energy systems.The new generation of geostationary meteorological satellite Himawari-8,with higher spatiotemporal and spectral resolution,offers a new ...Surface shortwave radiation(SSR)plays an important role in global energy systems.The new generation of geostationary meteorological satellite Himawari-8,with higher spatiotemporal and spectral resolution,offers a new opportunity to retrieve SSR with higher accuracy.In this study,an improved algorithm was applied to estimate instantaneous,hourly,and daily mean SSR using cloud products from the Advanced Himawari Imager(AHI)onboard the Himawari-8 satellite.The validation against Baseline Surface Radiation Network(BSRN)stations showed a root mean square error(RMSE)of 95.8 W m^(-2) for instantaneous SSR,82.4 W m^(-2) for hourly SSR,and 22.8 W m^(-2) for daily SSR and mean bias error(MBE)of-15.8 W m^(-2),-14.1 W m^(-2),and-6.6 W m^(-2).The validation against China Meteorological Administration(CMA)stations showed a RMSE of 99.5 W m^(-2) and MBE of-8.2 W m^(-2) for hourly SSR and RMSE of 27.7 W m^(-2) and MBE of-3.9 W m^(-2) for daily SSR,which are generally better than the Himawari-8 SSR product.Overall,the improved algorithm performed well on the new-generation geostationary satellite,with high accuracy and efficiency,and would contribute to surface process research and photovoltaic engineering applications.展开更多
To evaluate the validity of cloud top height (CTH) retrievals from FY-4A, the first of China's next-generation geostationary meteorological satellite series, the retrievals are compared to those from Himawari-8, C...To evaluate the validity of cloud top height (CTH) retrievals from FY-4A, the first of China's next-generation geostationary meteorological satellite series, the retrievals are compared to those from Himawari-8, CloudSat, Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO), and Moderate Resolution Imaging Spectroradiometer (MODIS) operational products from August to October 2017. Regarding CTHs from CloudSat, CALIPSO, and MODIS as truth, the results show that the performance of FY-4A CTH retrievals is similar to that of Himawari-8. Both FY-4A and Himawari-8 retrieve reasonable CTH values for single-layer clouds, but perform poorly for multi-layer clouds. The mean bias error (MBE) shows that the mean value of FY-4A CTH retrievals is smaller than that of Himawari-8 for single-layer clouds but larger for multi-layer clouds. For ice crystal clouds, both FY-4A and Himawari-8 obtain the underestimated CTHs. However, there is a tendency for FY-4A and Himawari-8 to overestimate the CTH values of CloudSat and CALIPSO mainly for low level liquid water clouds. The temperature inversion near the tops of water clouds may result in an overestimation of CTHs. According to the MBE change with altitude, FY-4A and Himawari-8 overestimate the CTHs mainly for clouds below 3 km, and the overestimation is slightly more apparent in Himawari-8 data than that in FY-4A values. As the cloud optical thickness (COT) increases, the CTH bias of FY-4A CTH retrievals gradually decreases. Two typical cases are analyzed to illustrate the differences between different satellites' CTH retrievals in detail.展开更多
Microwave Land Surface Emissivity(MLSE)over China under both clear and cloudy sky conditions was retrieved using measurements of recalibrated microwave brightness temperatures(Tbs)from Fengyun-3B Microwave Radiation I...Microwave Land Surface Emissivity(MLSE)over China under both clear and cloudy sky conditions was retrieved using measurements of recalibrated microwave brightness temperatures(Tbs)from Fengyun-3B Microwave Radiation Imager(FY-3B MWRI),combined with cloud properties derived from Himawari-8 Advanced Himawari Imager(AHI)observations.The contributions from cloud particles and atmospheric gases to the upwelling Tbs at the top of atmosphere were calculated and removed in radiative transfer.The MLSEs at horizontal polarizations at 10.65,18.7,and 36.5 GHz during 7 July 2015 to 30 June 2019 over China showed high values in the southeast vegetated area and low values in the northwest barren,or sparsely vegetated,area.The maximum values were found in the belt area of the Qinling-Taihang Mountains and the eastern edge of the Qinghai-Tibet Plateau,which is highly consistent with MLSEs derived from AMSR-E.It demonstrates that the measurements of FY-3B MWRI Tbs,including its calibration and validation,are reliable,and the retrieval algorithm developed in this study works well.Seasonal variations of MLSE in China are mainly driven by the combined effects of vegetation,rainfall,and snow cover.In tropical and southern forest regions,the seasonal variation of MLSE is small due to the enhancement from vegetation and the suppression from rainfall.In the boreal area,snow causes a significant decrease of MLSE at 36.5 GHz in winter.Meanwhile,the MLSE at lower frequencies experiences less suppression.In the desert region in Xinjiang,increases of MLSEs at all frequencies are observed with increasing snow cover.展开更多
基金funded by the National Natural Science Foundation of China(grant number 42171360)the National Key Research and Development Program of China(grant number 2017YFA0603604).
文摘Surface shortwave radiation(SSR)plays an important role in global energy systems.The new generation of geostationary meteorological satellite Himawari-8,with higher spatiotemporal and spectral resolution,offers a new opportunity to retrieve SSR with higher accuracy.In this study,an improved algorithm was applied to estimate instantaneous,hourly,and daily mean SSR using cloud products from the Advanced Himawari Imager(AHI)onboard the Himawari-8 satellite.The validation against Baseline Surface Radiation Network(BSRN)stations showed a root mean square error(RMSE)of 95.8 W m^(-2) for instantaneous SSR,82.4 W m^(-2) for hourly SSR,and 22.8 W m^(-2) for daily SSR and mean bias error(MBE)of-15.8 W m^(-2),-14.1 W m^(-2),and-6.6 W m^(-2).The validation against China Meteorological Administration(CMA)stations showed a RMSE of 99.5 W m^(-2) and MBE of-8.2 W m^(-2) for hourly SSR and RMSE of 27.7 W m^(-2) and MBE of-3.9 W m^(-2) for daily SSR,which are generally better than the Himawari-8 SSR product.Overall,the improved algorithm performed well on the new-generation geostationary satellite,with high accuracy and efficiency,and would contribute to surface process research and photovoltaic engineering applications.
基金Supported by the National Natural Science Foundation of China(41705007 and 41575028)
文摘To evaluate the validity of cloud top height (CTH) retrievals from FY-4A, the first of China's next-generation geostationary meteorological satellite series, the retrievals are compared to those from Himawari-8, CloudSat, Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO), and Moderate Resolution Imaging Spectroradiometer (MODIS) operational products from August to October 2017. Regarding CTHs from CloudSat, CALIPSO, and MODIS as truth, the results show that the performance of FY-4A CTH retrievals is similar to that of Himawari-8. Both FY-4A and Himawari-8 retrieve reasonable CTH values for single-layer clouds, but perform poorly for multi-layer clouds. The mean bias error (MBE) shows that the mean value of FY-4A CTH retrievals is smaller than that of Himawari-8 for single-layer clouds but larger for multi-layer clouds. For ice crystal clouds, both FY-4A and Himawari-8 obtain the underestimated CTHs. However, there is a tendency for FY-4A and Himawari-8 to overestimate the CTH values of CloudSat and CALIPSO mainly for low level liquid water clouds. The temperature inversion near the tops of water clouds may result in an overestimation of CTHs. According to the MBE change with altitude, FY-4A and Himawari-8 overestimate the CTHs mainly for clouds below 3 km, and the overestimation is slightly more apparent in Himawari-8 data than that in FY-4A values. As the cloud optical thickness (COT) increases, the CTH bias of FY-4A CTH retrievals gradually decreases. Two typical cases are analyzed to illustrate the differences between different satellites' CTH retrievals in detail.
基金the National Natural Science Foundation of China(Grant Nos.41830104,41661144007,41675022,and 41375148)Research and Development Program of China(Grant No.2017YFC1501402)the Jiangsu Provincial 2011 Program(Col-laborative Innovation Center of Climate Change).
文摘Microwave Land Surface Emissivity(MLSE)over China under both clear and cloudy sky conditions was retrieved using measurements of recalibrated microwave brightness temperatures(Tbs)from Fengyun-3B Microwave Radiation Imager(FY-3B MWRI),combined with cloud properties derived from Himawari-8 Advanced Himawari Imager(AHI)observations.The contributions from cloud particles and atmospheric gases to the upwelling Tbs at the top of atmosphere were calculated and removed in radiative transfer.The MLSEs at horizontal polarizations at 10.65,18.7,and 36.5 GHz during 7 July 2015 to 30 June 2019 over China showed high values in the southeast vegetated area and low values in the northwest barren,or sparsely vegetated,area.The maximum values were found in the belt area of the Qinling-Taihang Mountains and the eastern edge of the Qinghai-Tibet Plateau,which is highly consistent with MLSEs derived from AMSR-E.It demonstrates that the measurements of FY-3B MWRI Tbs,including its calibration and validation,are reliable,and the retrieval algorithm developed in this study works well.Seasonal variations of MLSE in China are mainly driven by the combined effects of vegetation,rainfall,and snow cover.In tropical and southern forest regions,the seasonal variation of MLSE is small due to the enhancement from vegetation and the suppression from rainfall.In the boreal area,snow causes a significant decrease of MLSE at 36.5 GHz in winter.Meanwhile,the MLSE at lower frequencies experiences less suppression.In the desert region in Xinjiang,increases of MLSEs at all frequencies are observed with increasing snow cover.
