Sea surface temperature(SST)is one of the important parameters of global ocean and climate research,which can be retrieved by satellite infrared and passive microwave remote sensing instruments.While satellite infrare...Sea surface temperature(SST)is one of the important parameters of global ocean and climate research,which can be retrieved by satellite infrared and passive microwave remote sensing instruments.While satellite infrared SST offers high spatial resolution,it is limited by cloud cover.On the other hand,passive microwave SST provides all-weather observation but suffers from poor spatial resolution and susceptibility to environmental factors such as rainfall,coastal effects,and high wind speeds.To achieve high-precision,comprehensive,and high-resolution SST data,it is essential to fuse infrared and microwave SST measurements.In this study,data from the Fengyun-3D(FY-3D)medium resolution spectral imager II(MERSI-II)SST and microwave imager(MWRI)SST were fused.Firstly,the accuracy of both MERSIII SST and MWRI SST was verified,and the latter was bilinearly interpolated to match the 5km resolution grid of MERSI SST.After pretreatment and quality control of MERSI SST and MWRI SST,a Piece-Wise Regression method was employed to correct biases in MWRI SST.Subsequently,SST data were selected based on spatial resolution and accuracy within a 3-day window of the analysis date.Finally,an optimal interpolation method was applied to fuse the FY-3D MERSI-II SST and MWRI SST.The results demonstrated a significant improvement in spatial coverage compared to MERSI-II SST and MWRI SST.Furthermore,the fusion SST retained true spatial distribution details and exhibited an accuracy of–0.12±0.74℃compared to OSTIA SST.This study has improved the accuracy of FY satellite fusion SST products in China.展开更多
Forward radiative transfer(RT)models are essential for atmospheric applications such as remote sensing and weather and climate models,where computational efficiency becomes equally as important as accuracy for high-re...Forward radiative transfer(RT)models are essential for atmospheric applications such as remote sensing and weather and climate models,where computational efficiency becomes equally as important as accuracy for high-resolution hyperspectral measurements that need rigorous RT simulations for thousands of channels.This study introduces a fast and accurate RT model for the hyperspectral infrared(HIR)sounder based on principal component analysis(PCA)or machine learning(i.e.,neural network,NN).The Geosynchronous Interferometric Infrared Sounder(GIIRS),the first HIR sounder onboard the geostationary Fengyun-4 satellites,is considered to be a candidate example for model development and validation.Our method uses either PCA or NN(PCA/NN)twice for the atmospheric transmittance and radiance,respectively,to reduce the number of independent but similar simulations to accelerate RT simulations;thereby,it is referred to as a multi-domain compression model.The first PCA/NN gives monochromatic gas transmittance in both spectral and atmospheric pressure domains for each gas independently.The second PCA/NN is performed in the traditional spectral radiance domain.Meanwhile,a new method is introduced to choose representative variables for the PCA/NN scheme developments.The model is three orders of magnitude faster than the standard line-by-line-based simulations with averaged brightness temperature difference(BTD)less than 0.1 K,and the compressions based on PCA or NN methods result in comparable efficiency and accuracy.Our fast model not only avoids an excessively complicated transmittance scheme by using PCA/NN but is also highly flexible for hyperspectral instruments with similar spectral ranges simply by updating the corresponding spectral response functions.展开更多
We use the High-energy Electron Experiments(HEP)instrument onboard Arase(ERG)to conduct an energy-dependent cross-satellite calibration of electron fluxes measured by the High Energy Particle Detector(HEPD)onboard Fen...We use the High-energy Electron Experiments(HEP)instrument onboard Arase(ERG)to conduct an energy-dependent cross-satellite calibration of electron fluxes measured by the High Energy Particle Detector(HEPD)onboard FengYun-4A(FY-4A)spanning from April 1,2017,to September 30,2019.By tracing the two-dimensional magnetic positions(L,magnetic local time[MLT])of FY-4A at each time,we compare the datasets of the conjugate electron fluxes over the range of 245–894 keV in 6 energy channels for the satellite pair within different sets of L×MLT.The variations in the electron fluxes observed by FY-4A generally agree with the Arase measurements,and the percentages of the ratios of electron flux conjunctions within a factor of 2 are larger than 50%.Compared with Arase,FY-4A systematically overestimates electron fluxes at all 6 energy channels,with the corresponding calibration factors ranging from 0.67 to 0.81.After the cross-satellite calibration,the electron flux conjunctions between FY-4A and Arase show better agreement,with much smaller normalized root mean square errors.Our results provide a valuable reference for the application of FY-4A high-energy electron datasets to in-depth investigations of the Earth’s radiation belt electron dynamics.展开更多
Based on the lightning observation data from the Fengyun-4A(FY-4A)Lightning Mapping Imager(FY-4A/LMI)and the Lightning Imaging Sensor(LIS)on the International Space Station(ISS),we extract the“event”type data as the...Based on the lightning observation data from the Fengyun-4A(FY-4A)Lightning Mapping Imager(FY-4A/LMI)and the Lightning Imaging Sensor(LIS)on the International Space Station(ISS),we extract the“event”type data as the lightning detection results.These observations are then compared with the cloud-to-ground(CG)lightning observation data from the China Meteorological Administration.This study focuses on the characteristics of lightning activity in Southeast China,primarily in Jiangxi Province and its adjacent areas,from April to September,2017–2022.In addition,with the fifth-generation European Centre for Medium-Range Weather Forecasts reanalysis data,we further delved into the potential factors influencing the distribution and variations in lightning activity and their primary related factors.Our findings indicate that the lightning frequency and density of the FY-4A/LMI,ISS-LIS and CG data are higher in southern and central Jiangxi,central Fujian Province,and western and central Guangdong Province,while they tend to be lower in eastern Hunan Province.In general,the high-value areas of lightning density for the FY-4A/LMI are located in inland mountainous areas.The lower the latitude is,the higher the CG lightning density is.High-value areas of the CG lightning density are more likely to be located in eastern Fujian and southeastern Zhejiang Province.However,the high-value areas of lightning density for the ISS-LIS are more dispersed,with a scattered distribution in inland mountainous areas and along the coast of eastern Fujian.Thus,the mountainous terrain is closely related to the high-value areas of the lightning density.The locations of the high-value areas of the lightning density for the FY-4A/LMI correspond well with those for the CG observations,and the seasonal variations are also consistent.In contrast,the distribution of the high-value areas of the lightning density for the ISS-LIS is more dispersed.The positions of the peak frequency of the FY-4A/LMI lightning and CG lightning contrast with local altitudes,primarily located at lower altitudes or near mountainsides.K-index and convective available potential energy(CAPE)can better reflect the local boundary layer conditions,where the lightning density is higher and lightning seasonal variations are apparent.There are strong correlations in the annual variations between the dew-point temperature(Td)and CG lightning frequency,and the monthly variations of the dew-point temperature and CAPE are also strongly correlated with monthly variations of CG lightning,while they are weakly correlated with the lightning frequency for the FY-4A/LMI and ISS-LIS.This result reflects that the CAPE shows a remarkable effect on the CG lightning frequency during seasonal transitions.展开更多
We studied the properties of the main phases of 24 super geomagnetic storms(SGSs)(ΔSYM-H≤-250 nT)since 1981.We divided the SGSs into two subgroups:SGSs-Ⅰ(-400 nT<ΔSYM-H≤-250 nT)and SGSs-Ⅱ(ΔSYM-H≤-400 nT).Of...We studied the properties of the main phases of 24 super geomagnetic storms(SGSs)(ΔSYM-H≤-250 nT)since 1981.We divided the SGSs into two subgroups:SGSs-Ⅰ(-400 nT<ΔSYM-H≤-250 nT)and SGSs-Ⅱ(ΔSYM-H≤-400 nT).Of the 24 SGSs,16 are SGSs-Ⅰand eight are SGSs-Ⅱ.The source locations of SGSs were distributed in the longitudinal scope of[E37,W66].95.8%of the SGSs were distributed in the longitudinal scope of[E37,W20].East and west hemispheres of the Sun had 14 and 10 SGSs,respectively.The durations of the main phases for six SGSs ranged from 2 to 4 hr.The durations of the main phases for the rest 18 SGSs were longer than 6.5 hr.The duration of the SGSs with source locations in the west hemisphere varied from 2.22 to 19.58 hr.The duration for the SGSs with the source locations in the east hemisphere ranged from 2.1 to31.88 hr.The averaged duration of the main phases of the SGSs in the west and east hemispheres are 8.3 hr and13.98 hr,respectively.|ΔSYM-H/Δt|for six SGSs with source locations distributed in the longitudinal area ranging from E15 to W20 was larger than 1.0 nT·minute^(-1),while|ΔSYM-H/Δt|for the rest 18 SGSs was lower than 1.0 nT·minute^(-1).|ΔSYM-H/Δt|for SGSs-Ⅰvaried from 0.18 to 3.0 nT·minute^(-1).|ΔSYM-H/Δt|for eight SGSs-Ⅱvaried from 0.37 to 2.2 nT·minute^(-1)with seven SGSs-Ⅱfalling in the scope from 0.37 to0.992 nT·minute^(-1).展开更多
Atmospheric water vapor is an essential climate variable(ECV)with extensive spatial and temporal variations.Microwave humidity observations from meteorological satellites provide important information for climate syst...Atmospheric water vapor is an essential climate variable(ECV)with extensive spatial and temporal variations.Microwave humidity observations from meteorological satellites provide important information for climate system variables,including atmospheric water vapor and precipitable water,and assimilation in numerical weather prediction(NWP)and reanalysis.As one of the payloads onboard China’s second-generation polar-orbiting operational meteorological Fengyun-3(FY-3)satellites,the Microwave Humidity Sounder(MWHS)has been continuously observing the global humidity since 2008.The reprocessing of historical FY-3 MWHS data is documented in detail in this study.After calibrating and correcting the data,the quality of the reprocessed dataset is evaluated and the improvement is shown in this study.The results suggest that MWHS observations bias is reduced to approximately 0.8 K,compared with METOP-A Microwave Humidity Sounder(MHS).The temporal variability of MWHS is highly correlated with the instrument temperature.After reprocessing,the scene temperature dependency is mitigated for all 183 GHz channels,and the consistency and stability between FY-3A/B/C are also improved.展开更多
The solar X-ray and Extreme Ultraviolet Imager(X-EUVI),developed by the Changchun Institute of Optics,Fine Mechanics and Physics,Chinese Academy of Sciences(CIOMP),is the first space-based solar X-ray and Extreme ultr...The solar X-ray and Extreme Ultraviolet Imager(X-EUVI),developed by the Changchun Institute of Optics,Fine Mechanics and Physics,Chinese Academy of Sciences(CIOMP),is the first space-based solar X-ray and Extreme ultraviolet(EUV)imager of China loaded on the Fengyun-3E(FY-3E)satellite supported by the China Meteorological Administration(CMA)for solar observation.Since started work on July 11,2021,X-EUVI has obtained many solar images.The instrument employs an innovative dual-band design to monitor a much larger temperature range on the Sun,which covers 0.6-8.0 nm in the X-ray region with six channels and 19.5 nm in the EUV region.X-EUVI has a field of view of 42′,an angular resolution of 2.5″per pixel in the EUV band and an angular resolution of 4.1″per pixel in the X-ray band.The instrument also includes an X-ray and EUV irradiance sensor(X-EUVS)with the same bands as its imaging optics,which measures the solar irradiance and regularly calibrates the solar images.The radiometric calibration of X-EUVS on the ground has been completed,with a calibration accuracy of 12%.X-EUVI is loaded on the FY-3E satellite and rotates relative to the Sun at a uniform rate.Flat-field calibration is conducted by utilizing successive rotation solar images.The agreement between preliminarily processed X-EUVI images and SDO/AIA and Hinode/XRT images indicates that X-EUVI and the data processing algorithm operate properly and that the data from X-EUVI can be applied to the space weather forecast system of CMA and scientific investigations on solar activity.展开更多
In order to improve the operational application ability of the Fengyun-4A(FY-4A)new sounding dataset,in this paper,validation of the FY-4A Geosynchronous Interferometric Infrared Sounder(FY-4A/GIIRS)temperature was ca...In order to improve the operational application ability of the Fengyun-4A(FY-4A)new sounding dataset,in this paper,validation of the FY-4A Geosynchronous Interferometric Infrared Sounder(FY-4A/GIIRS)temperature was carried out using the balloon sounding temperature from meteorological sounding stations.More than 350,000 samples were obtained through time–space matching,and the results show that the FY-4A/GIIRS temperature mean bias(MB)is 0.07°C,the mean absolute error(MAE)is 1.80°C,the root-mean-square error(RMSE)is 2.546°C,and the correlation coefficient(RR)is 0.95.The FY-4A/GIIRS temperature error is relatively larger in the upper and lower troposphere,and relatively smaller in the middle troposphere;that is,the temperature at 500 hPa is better than that at 850 hPa.The temporal variation is smaller in the upper and middle troposphere than in the lower troposphere.The reconstruction of missing data of FY-4A/GIIRS temperature in cloudy areas is also carried out and the results are evaluated.The spatial distribution of reconstructed FY-4A/GIIRS temperature and the fifth generation ECMWF reanalysis(ERA5)data is consistent and completely retains the minimum temperature center with high precision of FY-4A/GIIRS.There are more detailed characteristics of intensity and position at the cold center than that of the reanalysis data.Therefore,an operational satellite retrieval temperature product with time–space continuity and high accuracy is formed.The reconstructed FY-4A/GIIRS temperature is used to monitor a strong cold wave event in November 2021.The results show that the product effectively monitors the movement and intensity of cold air activities,and it also has good indication for the phase transition of rain and snow triggered by cold wave.展开更多
文摘Sea surface temperature(SST)is one of the important parameters of global ocean and climate research,which can be retrieved by satellite infrared and passive microwave remote sensing instruments.While satellite infrared SST offers high spatial resolution,it is limited by cloud cover.On the other hand,passive microwave SST provides all-weather observation but suffers from poor spatial resolution and susceptibility to environmental factors such as rainfall,coastal effects,and high wind speeds.To achieve high-precision,comprehensive,and high-resolution SST data,it is essential to fuse infrared and microwave SST measurements.In this study,data from the Fengyun-3D(FY-3D)medium resolution spectral imager II(MERSI-II)SST and microwave imager(MWRI)SST were fused.Firstly,the accuracy of both MERSIII SST and MWRI SST was verified,and the latter was bilinearly interpolated to match the 5km resolution grid of MERSI SST.After pretreatment and quality control of MERSI SST and MWRI SST,a Piece-Wise Regression method was employed to correct biases in MWRI SST.Subsequently,SST data were selected based on spatial resolution and accuracy within a 3-day window of the analysis date.Finally,an optimal interpolation method was applied to fuse the FY-3D MERSI-II SST and MWRI SST.The results demonstrated a significant improvement in spatial coverage compared to MERSI-II SST and MWRI SST.Furthermore,the fusion SST retained true spatial distribution details and exhibited an accuracy of–0.12±0.74℃compared to OSTIA SST.This study has improved the accuracy of FY satellite fusion SST products in China.
基金supported by the National Natural Science Foundation of China(Grant No.42122038)。
文摘Forward radiative transfer(RT)models are essential for atmospheric applications such as remote sensing and weather and climate models,where computational efficiency becomes equally as important as accuracy for high-resolution hyperspectral measurements that need rigorous RT simulations for thousands of channels.This study introduces a fast and accurate RT model for the hyperspectral infrared(HIR)sounder based on principal component analysis(PCA)or machine learning(i.e.,neural network,NN).The Geosynchronous Interferometric Infrared Sounder(GIIRS),the first HIR sounder onboard the geostationary Fengyun-4 satellites,is considered to be a candidate example for model development and validation.Our method uses either PCA or NN(PCA/NN)twice for the atmospheric transmittance and radiance,respectively,to reduce the number of independent but similar simulations to accelerate RT simulations;thereby,it is referred to as a multi-domain compression model.The first PCA/NN gives monochromatic gas transmittance in both spectral and atmospheric pressure domains for each gas independently.The second PCA/NN is performed in the traditional spectral radiance domain.Meanwhile,a new method is introduced to choose representative variables for the PCA/NN scheme developments.The model is three orders of magnitude faster than the standard line-by-line-based simulations with averaged brightness temperature difference(BTD)less than 0.1 K,and the compressions based on PCA or NN methods result in comparable efficiency and accuracy.Our fast model not only avoids an excessively complicated transmittance scheme by using PCA/NN but is also highly flexible for hyperspectral instruments with similar spectral ranges simply by updating the corresponding spectral response functions.
基金supported by the National Natural Science Foundation of China(Grant Nos.42025404,42188101,42241143,41931073,and 42204160)the National Key R&D Program of China(Grant Nos.2022YFF0503700,2022YFF0503900,and 2021YFA0718600)+1 种基金the B-type Strategic Priority Program of the Chinese Academy of Sciences(Grant No.XDB41000000)the Fundamental Research Funds for the Central Universities(Grant Nos.2042022kf1012 and 2042022kf1016).
文摘We use the High-energy Electron Experiments(HEP)instrument onboard Arase(ERG)to conduct an energy-dependent cross-satellite calibration of electron fluxes measured by the High Energy Particle Detector(HEPD)onboard FengYun-4A(FY-4A)spanning from April 1,2017,to September 30,2019.By tracing the two-dimensional magnetic positions(L,magnetic local time[MLT])of FY-4A at each time,we compare the datasets of the conjugate electron fluxes over the range of 245–894 keV in 6 energy channels for the satellite pair within different sets of L×MLT.The variations in the electron fluxes observed by FY-4A generally agree with the Arase measurements,and the percentages of the ratios of electron flux conjunctions within a factor of 2 are larger than 50%.Compared with Arase,FY-4A systematically overestimates electron fluxes at all 6 energy channels,with the corresponding calibration factors ranging from 0.67 to 0.81.After the cross-satellite calibration,the electron flux conjunctions between FY-4A and Arase show better agreement,with much smaller normalized root mean square errors.Our results provide a valuable reference for the application of FY-4A high-energy electron datasets to in-depth investigations of the Earth’s radiation belt electron dynamics.
基金National Natural Science Foundation of China(42175014,42205137)Open Research Fund of Institute of Meteorological Technology Innovation,Nanjing(BJG202202)+3 种基金Joint Research Project of Typhoon Research,Shanghai Typhoon Institute,China Meteorological Administration(TFJJ202209)Innovation Development Project of China Meteorological Administration(CXFZ2023P001)Open Project of KLME&CIC-FEMD(KLME202311)Jiangxi MDIA-ASI Fund。
文摘Based on the lightning observation data from the Fengyun-4A(FY-4A)Lightning Mapping Imager(FY-4A/LMI)and the Lightning Imaging Sensor(LIS)on the International Space Station(ISS),we extract the“event”type data as the lightning detection results.These observations are then compared with the cloud-to-ground(CG)lightning observation data from the China Meteorological Administration.This study focuses on the characteristics of lightning activity in Southeast China,primarily in Jiangxi Province and its adjacent areas,from April to September,2017–2022.In addition,with the fifth-generation European Centre for Medium-Range Weather Forecasts reanalysis data,we further delved into the potential factors influencing the distribution and variations in lightning activity and their primary related factors.Our findings indicate that the lightning frequency and density of the FY-4A/LMI,ISS-LIS and CG data are higher in southern and central Jiangxi,central Fujian Province,and western and central Guangdong Province,while they tend to be lower in eastern Hunan Province.In general,the high-value areas of lightning density for the FY-4A/LMI are located in inland mountainous areas.The lower the latitude is,the higher the CG lightning density is.High-value areas of the CG lightning density are more likely to be located in eastern Fujian and southeastern Zhejiang Province.However,the high-value areas of lightning density for the ISS-LIS are more dispersed,with a scattered distribution in inland mountainous areas and along the coast of eastern Fujian.Thus,the mountainous terrain is closely related to the high-value areas of the lightning density.The locations of the high-value areas of the lightning density for the FY-4A/LMI correspond well with those for the CG observations,and the seasonal variations are also consistent.In contrast,the distribution of the high-value areas of the lightning density for the ISS-LIS is more dispersed.The positions of the peak frequency of the FY-4A/LMI lightning and CG lightning contrast with local altitudes,primarily located at lower altitudes or near mountainsides.K-index and convective available potential energy(CAPE)can better reflect the local boundary layer conditions,where the lightning density is higher and lightning seasonal variations are apparent.There are strong correlations in the annual variations between the dew-point temperature(Td)and CG lightning frequency,and the monthly variations of the dew-point temperature and CAPE are also strongly correlated with monthly variations of CG lightning,while they are weakly correlated with the lightning frequency for the FY-4A/LMI and ISS-LIS.This result reflects that the CAPE shows a remarkable effect on the CG lightning frequency during seasonal transitions.
基金funded by the SinoSouth Africa Joint Research on Polar Space Environment(2021YFE0106400)International Cooperation Project on Scientific and Technological Innovation Between Governments+3 种基金National Key Plans on Research and Development,Ministry of Science and Technology,Chinathe Special Fund of the Institute of Geophysics,China Earthquake Administration(Grant No.DQJB21X26)CAS Key Laboratory of Solar Activity under No.KLSA202109the National Natural Science Foundation of China(Grant Nos.41074132,41474166,41774195 and 41774085)。
文摘We studied the properties of the main phases of 24 super geomagnetic storms(SGSs)(ΔSYM-H≤-250 nT)since 1981.We divided the SGSs into two subgroups:SGSs-Ⅰ(-400 nT<ΔSYM-H≤-250 nT)and SGSs-Ⅱ(ΔSYM-H≤-400 nT).Of the 24 SGSs,16 are SGSs-Ⅰand eight are SGSs-Ⅱ.The source locations of SGSs were distributed in the longitudinal scope of[E37,W66].95.8%of the SGSs were distributed in the longitudinal scope of[E37,W20].East and west hemispheres of the Sun had 14 and 10 SGSs,respectively.The durations of the main phases for six SGSs ranged from 2 to 4 hr.The durations of the main phases for the rest 18 SGSs were longer than 6.5 hr.The duration of the SGSs with source locations in the west hemisphere varied from 2.22 to 19.58 hr.The duration for the SGSs with the source locations in the east hemisphere ranged from 2.1 to31.88 hr.The averaged duration of the main phases of the SGSs in the west and east hemispheres are 8.3 hr and13.98 hr,respectively.|ΔSYM-H/Δt|for six SGSs with source locations distributed in the longitudinal area ranging from E15 to W20 was larger than 1.0 nT·minute^(-1),while|ΔSYM-H/Δt|for the rest 18 SGSs was lower than 1.0 nT·minute^(-1).|ΔSYM-H/Δt|for SGSs-Ⅰvaried from 0.18 to 3.0 nT·minute^(-1).|ΔSYM-H/Δt|for eight SGSs-Ⅱvaried from 0.37 to 2.2 nT·minute^(-1)with seven SGSs-Ⅱfalling in the scope from 0.37 to0.992 nT·minute^(-1).
基金Supported by the National Key Research and Development Program of China(2018YFB0504900 and 2018YFB0504902)National Natural Science Foundation of China(41775020,42005105,and 41905034)。
文摘Atmospheric water vapor is an essential climate variable(ECV)with extensive spatial and temporal variations.Microwave humidity observations from meteorological satellites provide important information for climate system variables,including atmospheric water vapor and precipitable water,and assimilation in numerical weather prediction(NWP)and reanalysis.As one of the payloads onboard China’s second-generation polar-orbiting operational meteorological Fengyun-3(FY-3)satellites,the Microwave Humidity Sounder(MWHS)has been continuously observing the global humidity since 2008.The reprocessing of historical FY-3 MWHS data is documented in detail in this study.After calibrating and correcting the data,the quality of the reprocessed dataset is evaluated and the improvement is shown in this study.The results suggest that MWHS observations bias is reduced to approximately 0.8 K,compared with METOP-A Microwave Humidity Sounder(MHS).The temporal variability of MWHS is highly correlated with the instrument temperature.After reprocessing,the scene temperature dependency is mitigated for all 183 GHz channels,and the consistency and stability between FY-3A/B/C are also improved.
基金supported in part by the National Science Foundation of China(Grant Nos.41931073,10878004,U1931118 and 42104166).
文摘The solar X-ray and Extreme Ultraviolet Imager(X-EUVI),developed by the Changchun Institute of Optics,Fine Mechanics and Physics,Chinese Academy of Sciences(CIOMP),is the first space-based solar X-ray and Extreme ultraviolet(EUV)imager of China loaded on the Fengyun-3E(FY-3E)satellite supported by the China Meteorological Administration(CMA)for solar observation.Since started work on July 11,2021,X-EUVI has obtained many solar images.The instrument employs an innovative dual-band design to monitor a much larger temperature range on the Sun,which covers 0.6-8.0 nm in the X-ray region with six channels and 19.5 nm in the EUV region.X-EUVI has a field of view of 42′,an angular resolution of 2.5″per pixel in the EUV band and an angular resolution of 4.1″per pixel in the X-ray band.The instrument also includes an X-ray and EUV irradiance sensor(X-EUVS)with the same bands as its imaging optics,which measures the solar irradiance and regularly calibrates the solar images.The radiometric calibration of X-EUVS on the ground has been completed,with a calibration accuracy of 12%.X-EUVI is loaded on the FY-3E satellite and rotates relative to the Sun at a uniform rate.Flat-field calibration is conducted by utilizing successive rotation solar images.The agreement between preliminarily processed X-EUVI images and SDO/AIA and Hinode/XRT images indicates that X-EUVI and the data processing algorithm operate properly and that the data from X-EUVI can be applied to the space weather forecast system of CMA and scientific investigations on solar activity.
基金Supported by the National Natural Science Foundation of China(42175014)National Key Research and Development Program of China(2021YFB3900400).
文摘In order to improve the operational application ability of the Fengyun-4A(FY-4A)new sounding dataset,in this paper,validation of the FY-4A Geosynchronous Interferometric Infrared Sounder(FY-4A/GIIRS)temperature was carried out using the balloon sounding temperature from meteorological sounding stations.More than 350,000 samples were obtained through time–space matching,and the results show that the FY-4A/GIIRS temperature mean bias(MB)is 0.07°C,the mean absolute error(MAE)is 1.80°C,the root-mean-square error(RMSE)is 2.546°C,and the correlation coefficient(RR)is 0.95.The FY-4A/GIIRS temperature error is relatively larger in the upper and lower troposphere,and relatively smaller in the middle troposphere;that is,the temperature at 500 hPa is better than that at 850 hPa.The temporal variation is smaller in the upper and middle troposphere than in the lower troposphere.The reconstruction of missing data of FY-4A/GIIRS temperature in cloudy areas is also carried out and the results are evaluated.The spatial distribution of reconstructed FY-4A/GIIRS temperature and the fifth generation ECMWF reanalysis(ERA5)data is consistent and completely retains the minimum temperature center with high precision of FY-4A/GIIRS.There are more detailed characteristics of intensity and position at the cold center than that of the reanalysis data.Therefore,an operational satellite retrieval temperature product with time–space continuity and high accuracy is formed.The reconstructed FY-4A/GIIRS temperature is used to monitor a strong cold wave event in November 2021.The results show that the product effectively monitors the movement and intensity of cold air activities,and it also has good indication for the phase transition of rain and snow triggered by cold wave.
