The high observation efficiency,scanning speed and observation frequency of the Fengyun-4A(FY-4A)satellite indicates the progress of Chinese geostationary meteorological satellites.The characteristics of FY-4A atmosph...The high observation efficiency,scanning speed and observation frequency of the Fengyun-4A(FY-4A)satellite indicates the progress of Chinese geostationary meteorological satellites.The characteristics of FY-4A atmospheric motion vectors(AMVs)derived from the high-level water vapor(WV-High)channel,mid-level water vapor(WV-Mid)channel,and infrared(IR)channel of FY-4A are analyzed,and their corresponding observation errors estimated.Then,the impacts of single-channel and multi-channel FY-4A AMVs on RMAPS-ST(the Rapid-refresh Multi-scale Analysis and Prediction System-Short Term)are evaluated based on one-month data assimilation cycling and forecasting experiments.Results show that the observation errors of FY-4A AMVs from the three channels have an explicit vertical structure.Results from the cycling experiments indicate that the assimilation of AMVs from WV-High produces more apparent improvement of the wind in the upper layer,while a more positive effect in the lower layer is achieved by the assimilation of AMVs from IR.Furthermore,the assimilation of AMVs from IR is more skillful for medium and moderate precipitation than from other channels owing to the good quality of data in the lower layer in the AMVs from IR.Assimilation of FY-4A AMVs from the three channels could combine the advantages of assimilation from each individual channel to improve the wind in the upper,middle and lower layers simultaneously.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
Surface solar irradiance(SSI)nowcasting(0-3 h)is an effective way to overcome the intermittency of solar energy and to ensure the safe operation of grid-connected solar power plants.In this study,an SSI estimate and n...Surface solar irradiance(SSI)nowcasting(0-3 h)is an effective way to overcome the intermittency of solar energy and to ensure the safe operation of grid-connected solar power plants.In this study,an SSI estimate and nowcasting system was established using the near-infrared channel of Fengyun-4A(FY-4A)geostationary satellite.The system is composed of two key components:The first is a hybrid SSI estimation method combining a physical clear-sky model and an empirical cloudy-sky model.The second component is the SSI nowcasting model,the core of which is the derivation of the cloud motion vector(CMV)using the block-matching method.The goal of simultaneous estimation and nowcasting of global horizontal irradiance(GHI)and direct normal irradiance(DNI)is fulfilled.The system was evaluated under different sky conditions using SSI measurements at Xianghe,a radiation station in the North China Plain.The results show that the accuracy of GHI estimation is higher than that of DNI estimation,with a normalized root-mean-square error(nRMSE)of 22.4%relative to 45.4%.The nRMSE of forecasting GHI and DNI at 30-180 min ahead varied within 25.1%-30.8%and 48.1%-53.4%,respectively.The discrepancy of SSI estimation depends on cloud occurrence frequency and shows a seasonal pattern,being lower in spring-summer and higher in autumn-winter.The FY-4A has great potential in supporting SSI nowcasting,which promotes the development of photovoltaic energy and the reduction of carbon emissions in China.The system can be improved further if calibration of the empirical method is improved.展开更多
This paper analyzes the sea surface backward thermal radiation data in the China Sea observed by the mmwave channel of FY3 MWRI, explains the reason for which the analysis method combined with multiple mmwave channels...This paper analyzes the sea surface backward thermal radiation data in the China Sea observed by the mmwave channel of FY3 MWRI, explains the reason for which the analysis method combined with multiple mmwave channels is conducive to wind inversion, uses the complex model of the two-scale randomly rough surface with foam scattering layer to calculate the backward heat emission, analyzes the different response characteristics of the thermal radiation characteristics of each channel with the change of the sea surface wind speed, and establishes the wind speed inversion model applying to the microwave radiometer, achieving better results than in previous studies. The sea surface medium-low wind speed precision standard deviation of new model reaches 1.2 m/s (0 - 15 m/s);the inversion strong wind data are consistent with the island fixed buoys data, and the global sea surface wind speed image schematic diagram is given.展开更多
FY-4 is the second generation of Chinese geostationary satellite for quantitative remote sensing meteorological application. The detection efficiency, spectral bands, spatial and time resolution have been greatly impr...FY-4 is the second generation of Chinese geostationary satellite for quantitative remote sensing meteorological application. The detection efficiency, spectral bands, spatial and time resolution have been greatly improved with respect to those of first generation, as well as the radiometric calibration and sensitivity. The combination of multichannel detection and vertical sounding was first realized on FY-4, because both the Advanced Geostationary Radiation Imager(AGRI) and Geostationary Interferometric Infrared Sounder(GIIRS) are on the same spacecraft. The main performance of the payloads including AGRI, GIIRS and Lightning Mapping Imager, and the spacecraft bus are presented, the performance being equivalent to the level of the third generation meteorological satellites in Europe and USA. The acquiring methods of remote sensing data including multichannel and high precision quantitative observing, imaging collection of the ground and cloud, vertical observation of atmospheric temperature and moisture, lightning imaging observation and space environment detection are shown. Several innovative technologies including high accuracy rotation angle detection and scanning control, high precision calibration, micro vibration suppression, unified reference of platform and payload and on-orbit measurement, real-time image navigation and registration on-orbit were applied in FY-4.展开更多
Based on the lightning monitoring and FY4A satellite data in 12 periods during a thunderstorm,the relationship between lightning activity and four satellite digital products:blackbody radiation brightness temperature(...Based on the lightning monitoring and FY4A satellite data in 12 periods during a thunderstorm,the relationship between lightning activity and four satellite digital products:blackbody radiation brightness temperature(TBB),cloud top temperature(CTT),cloud top height(CTH)and cloud top pressure(CTP)was quantitatively analyzed.The following conclusions were obtained:(1)at lightning location,90.5%of TBB values were less than 214.1 K;88.5%of CTT values were less than 207.7 K;88.5%of CTP values were less than 137.7 hPa,and 88.5%of CTH values were greater than 14872 m.At location without lightning,92.5%of TBB values were greater than 214.1 K;90.4%of CTT values were greater than 207.7 K;89%of CTP values were greater than 137.7 hPa,and 92%of CTH values were less than 14872 m.(2)Lightning activity was concentrated in the cloud area with TBB between 190-210 K,CTT between 185-210 K,CTP between 50-150 hPa and CTH between 12-18 km.Lightning intensity was roughly positively correlated with TBB,CTT and CTP,and negatively correlated with CTH.With the increase of CTH,lightning intensity decreased.(3)TBB,CTT,CTP and CTH can well indicate the location and activity frequency of lightning in thunderstorm weather.展开更多
On September 25,the on-orbit delivery ceremony for China’s new generation geostationary meteorological satellite FY-4 was held in Beijing.China Aerospace Science and Technology Corporation（CASC）,the manufacturer of...On September 25,the on-orbit delivery ceremony for China’s new generation geostationary meteorological satellite FY-4 was held in Beijing.China Aerospace Science and Technology Corporation（CASC）,the manufacturer of the satellite officially delivered FY-4 to the customer,the China Meteorological Administration（CMA）for operation.展开更多
A 28 V-half-regulated power bus topology and an integrated PCDU (Power Conditioning and Distribution Unit) were adopted to meet the energy demand for the Chang'e 4 relay satellite.This paper first introduces the m...A 28 V-half-regulated power bus topology and an integrated PCDU (Power Conditioning and Distribution Unit) were adopted to meet the energy demand for the Chang'e 4 relay satellite.This paper first introduces the mission features and composition of the PSDS (Power Supply and Distribution System) for the Chang'e 4 relay satellite.Due to this satellite's unusual orbit,operational mode and project restrictions,special analysis and design was conducted on the PSDS from the perspective of weight-reduction,power management,and reliability and so on.Extreme low temperature storage of SA (Solar Array) was considered and how the antenna affects the SA was analyzed.A new kind of high-specific-energy 45 Ah (Ampere-hour) battery cell was used for the first time.To make sure that the satellite would successfully pass the long shadow zones,a 100% DOD (Depth of Discharge) experiment was carried out on the battery.Since the sunlight is almost always available and there are very few times for the battery to charge or discharge,battery care to extend its lifetime is also discussed.PCDU is a device that integrates power conditioning and power distribution in one unit.The PCDU on Chang'e 4 relay satellite can output more power with less weight because of the adoption of a 28 V-half-regulated power bus topology which was also used for the first time and used lighter material for its mechanical framework.Experiment under low temperature on PCDU was conducted as well and a hot backup equalizing charge technique which is beneficial to keep performance of the battery is illustrated.The power distribution module,which is a module of PCDU,enhances the power utilization security by utilizing a static impedance measurement and build-in-test to avoid possible short circuits.As for EED (Electrical Explosive Device) module,a protection plug was specially designed and three switches with different functions were connected in series to prevent the EED from exploding by error.In addition,the allowable minimum EED bus voltage for each EED was evaluated in case of low battery voltage caused by the possible postponement of the launching time.Complete verification experiments on the ground were conducted to confirm the correctness of the design and on-orbit test data conformed to the expected results and theoretical calculation.The power supply and distribution system has been working normally since the day the Chang'e 4 relay satellite was launched into space.展开更多
Satellite data sets are an asset in global gravity collections;their characteristics vary in coverage and resolution. New collections appear often, and the user must adapt fast to their characteristics. Their use in g...Satellite data sets are an asset in global gravity collections;their characteristics vary in coverage and resolution. New collections appear often, and the user must adapt fast to their characteristics. Their use in geophysical modeling is rapidly increasing;with this in mind we compare two of the most densely populated sets: EIGEN-6C4 and GGMplus. We characterize them in terms of their frequency histograms, Free Air anomalies, power spectrum, and simple Bouguer anomalies. The nature of the digital elevation models used for data reduction is discussed. We conclude that the GGMplus data set offers a better spatial resolution. To evaluate their effect in geophysical modelling, we chose an inland region with a prominent volcanic structure in which we perform 3D inversions of the respective Bouguer anomalies, obtaining density variations that in principle can be associated with the geologic materials and the structure of the volcanic edifice. Model results are analyzed along sections of the inverted data;we conclude that the GGMplus data set offers higher resolution in the cases analyzed.展开更多
At 11:17 on January 9,a LM-4B carrier rocket lifted off from the Taiyuan Satellite Launch Center,sending the first high-precision civilian stereo mapping satellite of China,Ziyuan 3 (ZY-3),into its preset orbit,markin...At 11:17 on January 9,a LM-4B carrier rocket lifted off from the Taiyuan Satellite Launch Center,sending the first high-precision civilian stereo mapping satellite of China,Ziyuan 3 (ZY-3),into its preset orbit,marking the first launch mission of 2012 a success.A small satellite of Luxembourg,VesselSat-2,was launched aboard the LM-4B as well.The ZY-3 satellite weighs 2650kg with a design lifetime of 5 years.The satellite was built to acquire rapidly展开更多
At 15:06 on May 10, China successfully sent Yaogan 14 satellite and Tiantuo 1 satellite into space with a Long March 4B rocket from the Taiyuan Satellite Launch Center. It marks another launch of two satellites by one...At 15:06 on May 10, China successfully sent Yaogan 14 satellite and Tiantuo 1 satellite into space with a Long March 4B rocket from the Taiyuan Satellite Launch Center. It marks another launch of two satellites by one rocket following the launch of two BeiDou (Compass) satellites by one rocket on April 30, and it is also the third consecutive launch mission conducted by CASC within 10 days.展开更多
Two experimental satellites, Chuangxin 1-03 and Shiyan Satellite 4, were put into orbit on a LM-2D launch vehicle from the Jiuquan Satellite Launch Center (JSLC) in northwest China's Gansu Province on November 20.
We used CHAMP satellite vector data and the latest IGRF12 model to investigate the regional magnetic anomalies over China's Mainland. We assumed satellite points on the same surface （307.69 km） and constructed a...We used CHAMP satellite vector data and the latest IGRF12 model to investigate the regional magnetic anomalies over China's Mainland. We assumed satellite points on the same surface （307.69 km） and constructed a spherical cap harmonic model of the satellite magnetic anomalies for elements X, Y, Z, and F over Chinese mainland for 2010.0 （SCH2010） based on selected 498 points. We removed the external field by using the CM4 model. The pole of the spherical cap is 36N° and 104°E, and its half-angle is 30°. After checking and comparing the root mean square （RMS） error of AX, AY, and AZ and X, Y, and Z, we established the truncation level at Kmax = 9. The results suggest that the created China Geomagnetic Referenced Field at the satellite level （CGRF2010） is consistent with the CM4 model. We compared the SCH2010 with other models and found that the intensities and distributions are consistent. In view of the variation off at different altitudes, the SCH2010 model results obey the basics of the geomagnetic field. Moreover, the change rate of X, Y, and Z for SCH2010 and CM4 are consistent. The proposed model can successfully reproduce the geomagnetic data, as other data-fitting models, but the inherent sources of error have to be considered as well.展开更多
After nearly 50 years of development, Fengyun(FY) satellite ushered in its best moment. China has become one of the three countries or units in the world(China, USA, and EU) that maintain both polar orbit and geostati...After nearly 50 years of development, Fengyun(FY) satellite ushered in its best moment. China has become one of the three countries or units in the world(China, USA, and EU) that maintain both polar orbit and geostationary orbit satellites operationally. Up to now, there are 17 Fengyun(FY) satellites that have been launched successfully since 1988. There are two FY polar orbital satellites and four FY geostationary orbit satellites operate in the space to provide a huge amount of the earth observation data to the user communities. The FY satellite data has been applied not only in the meteorological but also in agriculture,hydraulic engineering, environmental, education, scientific research and other fields. More recently, three meteorological satellites have been launched within the past two years. They are FY-4 A on 11 December2016, FY-3 D on 15 November 2017 and FY-2 H on 5 June 2018. This paper introduces the current status of FY meteorological satellites and data service. The updates of the latest three satellites have been addressed.The characteristics of their payloads on-boarding have been specified in details and the benefit fields have been anticipated separately.展开更多
Assimilation of the Advanced Geostationary Radiance Imager(AGRI)clear-sky radiance in a regional model is performed.The forecasting effectiveness of the assimilation of two water vapor(WV)channels with conventional ob...Assimilation of the Advanced Geostationary Radiance Imager(AGRI)clear-sky radiance in a regional model is performed.The forecasting effectiveness of the assimilation of two water vapor(WV)channels with conventional observations for the“21·7”Henan extremely heavy rainfall is analyzed and compared with a baseline test that assimilates only conventional observations in this study.The results show that the 24-h cumulative precipitation forecast by the assimilation experiment with the addition of the AGRI exceeds 500 mm,compared to a maximum value of 532.6 mm measured by the national meteorological stations,and that the location of the maximum precipitation is consistent with the observations.The results for the short periods of intense precipitation processes are that the simulation of the location and intensity of the 3-h cumulative precipitation is also relatively accurate.The analysis increment shows that the main difference between the two sets of assimilation experiments is over the ocean due to the additional ocean observations provided by FY-4A,which compensates for the lack of ocean observations.The assimilation of satellite data adjusts the vertical and horizontal wind fields over the ocean by adjusting the atmospheric temperature and humidity,which ultimately results in a narrower and stronger WV transport path to the center of heavy precipitation in Zhengzhou in the lower troposphere.Conversely,the WV convergence and upward motion in the control experiment are more dispersed;therefore,the precipitation centers are also correspondingly more dispersed.展开更多
Improving the gravity field recovery in terms of error levels and more isotropic noise distribution by adding cross-track and radial information to the satellite observables has been investigated through a number of s...Improving the gravity field recovery in terms of error levels and more isotropic noise distribution by adding cross-track and radial information to the satellite observables has been investigated through a number of studies by a variety of satellite constellations, i.e. satellite pairs that orbit the Earth in alternative configurations than the current GRACE (Gravity Recovery And Climate Experiment) gravity mission. This contribution gives for the first time a comparative study considering the recovery of the global gravity field from three constellations flying in satellite pairs in different directions (i.e. along-track, cross-track and radial). The three constellations include: 1) Foursatellite Bender configuration (flying in two pairs) of type along-track observations, 2) Three-satellite GRAPEN (combined GRACE with Pendulum formations) configuration of type cross-alongtrack observations, 3) Four-satellite Cartwheel configuration (flying in two pairs) of type radialalong-track observations. Additionally, a GRACE mission scenario is added as a reference “comparative” mission. The orbits of all satellites are considered to fly with drag-free system, however, realistic white noise has been added to the simulated observations to mimic the error associated with the drag-free measurement. The results are analyzed in the spectral wavelength spectrum of the gravity field up to a spherical harmonics degree of n = 100 and are plotted spatially on earth maps. The results show that the Three-satellite GRAPEN constellation provides, besides its low economically launches, an improved gravity field solution with respect to the Four-satellite Bender and the Four-satellite Cartwheel constellations.展开更多
基金the National Key Research and Development Plan(Grant No.2018YFC1507105).
文摘The high observation efficiency,scanning speed and observation frequency of the Fengyun-4A(FY-4A)satellite indicates the progress of Chinese geostationary meteorological satellites.The characteristics of FY-4A atmospheric motion vectors(AMVs)derived from the high-level water vapor(WV-High)channel,mid-level water vapor(WV-Mid)channel,and infrared(IR)channel of FY-4A are analyzed,and their corresponding observation errors estimated.Then,the impacts of single-channel and multi-channel FY-4A AMVs on RMAPS-ST(the Rapid-refresh Multi-scale Analysis and Prediction System-Short Term)are evaluated based on one-month data assimilation cycling and forecasting experiments.Results show that the observation errors of FY-4A AMVs from the three channels have an explicit vertical structure.Results from the cycling experiments indicate that the assimilation of AMVs from WV-High produces more apparent improvement of the wind in the upper layer,while a more positive effect in the lower layer is achieved by the assimilation of AMVs from IR.Furthermore,the assimilation of AMVs from IR is more skillful for medium and moderate precipitation than from other channels owing to the good quality of data in the lower layer in the AMVs from IR.Assimilation of FY-4A AMVs from the three channels could combine the advantages of assimilation from each individual channel to improve the wind in the upper,middle and lower layers simultaneously.
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supported by the National Natural Science Foundation of China(Grant Nos.42030608,41805021,and 51776051)the Beijing Natural Science Foundation(Grant No.8204072)Beijing Nova Program(Grant No.Z211100002121077).
文摘Surface solar irradiance(SSI)nowcasting(0-3 h)is an effective way to overcome the intermittency of solar energy and to ensure the safe operation of grid-connected solar power plants.In this study,an SSI estimate and nowcasting system was established using the near-infrared channel of Fengyun-4A(FY-4A)geostationary satellite.The system is composed of two key components:The first is a hybrid SSI estimation method combining a physical clear-sky model and an empirical cloudy-sky model.The second component is the SSI nowcasting model,the core of which is the derivation of the cloud motion vector(CMV)using the block-matching method.The goal of simultaneous estimation and nowcasting of global horizontal irradiance(GHI)and direct normal irradiance(DNI)is fulfilled.The system was evaluated under different sky conditions using SSI measurements at Xianghe,a radiation station in the North China Plain.The results show that the accuracy of GHI estimation is higher than that of DNI estimation,with a normalized root-mean-square error(nRMSE)of 22.4%relative to 45.4%.The nRMSE of forecasting GHI and DNI at 30-180 min ahead varied within 25.1%-30.8%and 48.1%-53.4%,respectively.The discrepancy of SSI estimation depends on cloud occurrence frequency and shows a seasonal pattern,being lower in spring-summer and higher in autumn-winter.The FY-4A has great potential in supporting SSI nowcasting,which promotes the development of photovoltaic energy and the reduction of carbon emissions in China.The system can be improved further if calibration of the empirical method is improved.
文摘This paper analyzes the sea surface backward thermal radiation data in the China Sea observed by the mmwave channel of FY3 MWRI, explains the reason for which the analysis method combined with multiple mmwave channels is conducive to wind inversion, uses the complex model of the two-scale randomly rough surface with foam scattering layer to calculate the backward heat emission, analyzes the different response characteristics of the thermal radiation characteristics of each channel with the change of the sea surface wind speed, and establishes the wind speed inversion model applying to the microwave radiometer, achieving better results than in previous studies. The sea surface medium-low wind speed precision standard deviation of new model reaches 1.2 m/s (0 - 15 m/s);the inversion strong wind data are consistent with the island fixed buoys data, and the global sea surface wind speed image schematic diagram is given.
文摘FY-4 is the second generation of Chinese geostationary satellite for quantitative remote sensing meteorological application. The detection efficiency, spectral bands, spatial and time resolution have been greatly improved with respect to those of first generation, as well as the radiometric calibration and sensitivity. The combination of multichannel detection and vertical sounding was first realized on FY-4, because both the Advanced Geostationary Radiation Imager(AGRI) and Geostationary Interferometric Infrared Sounder(GIIRS) are on the same spacecraft. The main performance of the payloads including AGRI, GIIRS and Lightning Mapping Imager, and the spacecraft bus are presented, the performance being equivalent to the level of the third generation meteorological satellites in Europe and USA. The acquiring methods of remote sensing data including multichannel and high precision quantitative observing, imaging collection of the ground and cloud, vertical observation of atmospheric temperature and moisture, lightning imaging observation and space environment detection are shown. Several innovative technologies including high accuracy rotation angle detection and scanning control, high precision calibration, micro vibration suppression, unified reference of platform and payload and on-orbit measurement, real-time image navigation and registration on-orbit were applied in FY-4.
基金Supported by Guizhou Provincial Science and Technology Fund Project(QIANKEHEJICHU-ZK[2022]GENERAL245)。
文摘Based on the lightning monitoring and FY4A satellite data in 12 periods during a thunderstorm,the relationship between lightning activity and four satellite digital products:blackbody radiation brightness temperature(TBB),cloud top temperature(CTT),cloud top height(CTH)and cloud top pressure(CTP)was quantitatively analyzed.The following conclusions were obtained:(1)at lightning location,90.5%of TBB values were less than 214.1 K;88.5%of CTT values were less than 207.7 K;88.5%of CTP values were less than 137.7 hPa,and 88.5%of CTH values were greater than 14872 m.At location without lightning,92.5%of TBB values were greater than 214.1 K;90.4%of CTT values were greater than 207.7 K;89%of CTP values were greater than 137.7 hPa,and 92%of CTH values were less than 14872 m.(2)Lightning activity was concentrated in the cloud area with TBB between 190-210 K,CTT between 185-210 K,CTP between 50-150 hPa and CTH between 12-18 km.Lightning intensity was roughly positively correlated with TBB,CTT and CTP,and negatively correlated with CTH.With the increase of CTH,lightning intensity decreased.(3)TBB,CTT,CTP and CTH can well indicate the location and activity frequency of lightning in thunderstorm weather.
文摘On September 25,the on-orbit delivery ceremony for China’s new generation geostationary meteorological satellite FY-4 was held in Beijing.China Aerospace Science and Technology Corporation（CASC）,the manufacturer of the satellite officially delivered FY-4 to the customer,the China Meteorological Administration（CMA）for operation.
文摘A 28 V-half-regulated power bus topology and an integrated PCDU (Power Conditioning and Distribution Unit) were adopted to meet the energy demand for the Chang'e 4 relay satellite.This paper first introduces the mission features and composition of the PSDS (Power Supply and Distribution System) for the Chang'e 4 relay satellite.Due to this satellite's unusual orbit,operational mode and project restrictions,special analysis and design was conducted on the PSDS from the perspective of weight-reduction,power management,and reliability and so on.Extreme low temperature storage of SA (Solar Array) was considered and how the antenna affects the SA was analyzed.A new kind of high-specific-energy 45 Ah (Ampere-hour) battery cell was used for the first time.To make sure that the satellite would successfully pass the long shadow zones,a 100% DOD (Depth of Discharge) experiment was carried out on the battery.Since the sunlight is almost always available and there are very few times for the battery to charge or discharge,battery care to extend its lifetime is also discussed.PCDU is a device that integrates power conditioning and power distribution in one unit.The PCDU on Chang'e 4 relay satellite can output more power with less weight because of the adoption of a 28 V-half-regulated power bus topology which was also used for the first time and used lighter material for its mechanical framework.Experiment under low temperature on PCDU was conducted as well and a hot backup equalizing charge technique which is beneficial to keep performance of the battery is illustrated.The power distribution module,which is a module of PCDU,enhances the power utilization security by utilizing a static impedance measurement and build-in-test to avoid possible short circuits.As for EED (Electrical Explosive Device) module,a protection plug was specially designed and three switches with different functions were connected in series to prevent the EED from exploding by error.In addition,the allowable minimum EED bus voltage for each EED was evaluated in case of low battery voltage caused by the possible postponement of the launching time.Complete verification experiments on the ground were conducted to confirm the correctness of the design and on-orbit test data conformed to the expected results and theoretical calculation.The power supply and distribution system has been working normally since the day the Chang'e 4 relay satellite was launched into space.
文摘Satellite data sets are an asset in global gravity collections;their characteristics vary in coverage and resolution. New collections appear often, and the user must adapt fast to their characteristics. Their use in geophysical modeling is rapidly increasing;with this in mind we compare two of the most densely populated sets: EIGEN-6C4 and GGMplus. We characterize them in terms of their frequency histograms, Free Air anomalies, power spectrum, and simple Bouguer anomalies. The nature of the digital elevation models used for data reduction is discussed. We conclude that the GGMplus data set offers a better spatial resolution. To evaluate their effect in geophysical modelling, we chose an inland region with a prominent volcanic structure in which we perform 3D inversions of the respective Bouguer anomalies, obtaining density variations that in principle can be associated with the geologic materials and the structure of the volcanic edifice. Model results are analyzed along sections of the inverted data;we conclude that the GGMplus data set offers higher resolution in the cases analyzed.
文摘At 11:17 on January 9,a LM-4B carrier rocket lifted off from the Taiyuan Satellite Launch Center,sending the first high-precision civilian stereo mapping satellite of China,Ziyuan 3 (ZY-3),into its preset orbit,marking the first launch mission of 2012 a success.A small satellite of Luxembourg,VesselSat-2,was launched aboard the LM-4B as well.The ZY-3 satellite weighs 2650kg with a design lifetime of 5 years.The satellite was built to acquire rapidly
文摘At 15:06 on May 10, China successfully sent Yaogan 14 satellite and Tiantuo 1 satellite into space with a Long March 4B rocket from the Taiyuan Satellite Launch Center. It marks another launch of two satellites by one rocket following the launch of two BeiDou (Compass) satellites by one rocket on April 30, and it is also the third consecutive launch mission conducted by CASC within 10 days.
文摘Two experimental satellites, Chuangxin 1-03 and Shiyan Satellite 4, were put into orbit on a LM-2D launch vehicle from the Jiuquan Satellite Launch Center (JSLC) in northwest China's Gansu Province on November 20.
基金supported by the National Natural Science Foundation of China(No.41404053)Special Project for MeteoScientifi c Research in the Public Interest(No.GYHY201306073)+2 种基金the Natural Science Foundation of Jiangsu Province(No.BK20140994)the Natural Science Foundation of Higher Education Institutions of Jiangsu Province(No.14KJB170012)the Training Program of Innovation and Entrepreneurship for Undergraduates of NUIST(No.201510300178)
文摘We used CHAMP satellite vector data and the latest IGRF12 model to investigate the regional magnetic anomalies over China's Mainland. We assumed satellite points on the same surface （307.69 km） and constructed a spherical cap harmonic model of the satellite magnetic anomalies for elements X, Y, Z, and F over Chinese mainland for 2010.0 （SCH2010） based on selected 498 points. We removed the external field by using the CM4 model. The pole of the spherical cap is 36N° and 104°E, and its half-angle is 30°. After checking and comparing the root mean square （RMS） error of AX, AY, and AZ and X, Y, and Z, we established the truncation level at Kmax = 9. The results suggest that the created China Geomagnetic Referenced Field at the satellite level （CGRF2010） is consistent with the CM4 model. We compared the SCH2010 with other models and found that the intensities and distributions are consistent. In view of the variation off at different altitudes, the SCH2010 model results obey the basics of the geomagnetic field. Moreover, the change rate of X, Y, and Z for SCH2010 and CM4 are consistent. The proposed model can successfully reproduce the geomagnetic data, as other data-fitting models, but the inherent sources of error have to be considered as well.
基金Supported by the National Key Research＆Development Program of China(2018YFB0504900,2018YFB0504901,2018YFB0504905)
文摘After nearly 50 years of development, Fengyun(FY) satellite ushered in its best moment. China has become one of the three countries or units in the world(China, USA, and EU) that maintain both polar orbit and geostationary orbit satellites operationally. Up to now, there are 17 Fengyun(FY) satellites that have been launched successfully since 1988. There are two FY polar orbital satellites and four FY geostationary orbit satellites operate in the space to provide a huge amount of the earth observation data to the user communities. The FY satellite data has been applied not only in the meteorological but also in agriculture,hydraulic engineering, environmental, education, scientific research and other fields. More recently, three meteorological satellites have been launched within the past two years. They are FY-4 A on 11 December2016, FY-3 D on 15 November 2017 and FY-2 H on 5 June 2018. This paper introduces the current status of FY meteorological satellites and data service. The updates of the latest three satellites have been addressed.The characteristics of their payloads on-boarding have been specified in details and the benefit fields have been anticipated separately.
基金supported by the National Key R&D Program of China(Grant Nos.2017YFC1501803 and 2017YFC1502102)。
文摘Assimilation of the Advanced Geostationary Radiance Imager(AGRI)clear-sky radiance in a regional model is performed.The forecasting effectiveness of the assimilation of two water vapor(WV)channels with conventional observations for the“21·7”Henan extremely heavy rainfall is analyzed and compared with a baseline test that assimilates only conventional observations in this study.The results show that the 24-h cumulative precipitation forecast by the assimilation experiment with the addition of the AGRI exceeds 500 mm,compared to a maximum value of 532.6 mm measured by the national meteorological stations,and that the location of the maximum precipitation is consistent with the observations.The results for the short periods of intense precipitation processes are that the simulation of the location and intensity of the 3-h cumulative precipitation is also relatively accurate.The analysis increment shows that the main difference between the two sets of assimilation experiments is over the ocean due to the additional ocean observations provided by FY-4A,which compensates for the lack of ocean observations.The assimilation of satellite data adjusts the vertical and horizontal wind fields over the ocean by adjusting the atmospheric temperature and humidity,which ultimately results in a narrower and stronger WV transport path to the center of heavy precipitation in Zhengzhou in the lower troposphere.Conversely,the WV convergence and upward motion in the control experiment are more dispersed;therefore,the precipitation centers are also correspondingly more dispersed.
文摘Improving the gravity field recovery in terms of error levels and more isotropic noise distribution by adding cross-track and radial information to the satellite observables has been investigated through a number of studies by a variety of satellite constellations, i.e. satellite pairs that orbit the Earth in alternative configurations than the current GRACE (Gravity Recovery And Climate Experiment) gravity mission. This contribution gives for the first time a comparative study considering the recovery of the global gravity field from three constellations flying in satellite pairs in different directions (i.e. along-track, cross-track and radial). The three constellations include: 1) Foursatellite Bender configuration (flying in two pairs) of type along-track observations, 2) Three-satellite GRAPEN (combined GRACE with Pendulum formations) configuration of type cross-alongtrack observations, 3) Four-satellite Cartwheel configuration (flying in two pairs) of type radialalong-track observations. Additionally, a GRACE mission scenario is added as a reference “comparative” mission. The orbits of all satellites are considered to fly with drag-free system, however, realistic white noise has been added to the simulated observations to mimic the error associated with the drag-free measurement. The results are analyzed in the spectral wavelength spectrum of the gravity field up to a spherical harmonics degree of n = 100 and are plotted spatially on earth maps. The results show that the Three-satellite GRAPEN constellation provides, besides its low economically launches, an improved gravity field solution with respect to the Four-satellite Bender and the Four-satellite Cartwheel constellations.
