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| 1 | 利用星载激光雷达资料研究东亚地区云垂直分布的统计特征显示文摘已有研究表明:云的垂直结构(简称CVS)是一个在卫星资料反演和气候模式预测中很重要的云特征。本文通过利用美国2006年刚发射的卫星CALIPSO(Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Obser-vations)所负载的激光雷达Level2_05km的云数据,研究了东亚地区(18°N^53°N,74°E^144°E)云的垂直分布特征。结果表明:东亚地区多层云云量在夏季、秋季、冬季、春季分别为43.6%、29.6%、21.1%、33.3%,而多层云分布中双层云比例最大。云顶和云底高度除了随季节变化显著外,还有明显的区域特征。单层云、双层云以及三层云的云顶和云底高度的数据显示,三层云中最上层的云顶和云底最高,并始终高于两层云中最上层云的云顶和云底高度。平均云层厚度季节变化不明显,其值普遍在0.9~2km范围之间。而云层间距同样没有明显的季节和区域变化,其出现的概率随距离的增大而减小。其中,间距在0.35km的概率最大,占到将近50%。而间距在1.45km附近的概率大约为15%,高一点的可达到20%。 | 李积明 黄建平 衣育红 吕达仁 | 2009 | 大气科学2009，33，4： | 72 |
| 2 | The trend, seasonal cycle, and sources of tropospheric NO_2 over China during 1997―2006 based on satellite measurement显示文摘The characteristics of spatial and temporal distribution of tropospheric NO2 column density concen-tration over China are presented,on the basis of measurements from the satellite instruments GOME and SCIAMACHY.From these observations,monthly averaged tropospheric NO2 variations are deter-mined for the period of 1997 to 2006.The trend and seasonal cycle are also investigated.The possible source of tropospheric NO2 over megacity area is discussed in this paper.The results show a large growth of tropospheric NO2 over eastern China,especially above the industrial areas with a fast eco-nomical growth,such as,Yangtze Rive Delta region and Pearl River Delta region because of the prominent anthropogenic activity.There is a rapid increase of tropospheric NO2 over megacities in China.For instance,Shanghai had a linear significant increase in NO2 columns of ~20% per year(ref-erence year 1997) in the period of 1997―2006,which is the rapidest increase among all the selected cities.The seasonal pattern of the NO2 concentration shows a difference between the east and west in China.In the eastern part of China,an expected winter maximum in seasonal cycle is found because of the prominent anthropogenic activity and meteorological conditions.In the western part this cycle shows a NO2 maximum in summer time,which is attributed to natural emissions,especially soil emissions and lightning.A quickly increasing vehicle population may contribute to the increase of tropo-spheric NO2 over megacities in China for the remarkable correlation for vehicle population with tropospheric NO2. | ZHANG XingYing ZHANG Peng ZHANG Yan LI XiaoJing QIU Hong | 2007 | Science China Earth Sciences2007，50，12： | 30 |
| 3 | Latest Progress of the Chinese Meteorological Satellite Program and Core Data Processing Technologies显示文摘In this paper,the latest progress,major achievements and future plans of Chinese meteorological satellites and the core data processing techniques are discussed.First,the latest three FengYun(FY)meteorological satellites(FY-2H,FY-3D,and FY-4A)and their primary objectives are introduced Second,the core image navigation techniques and accuracies of the FY meteorological satellites are elaborated,including the latest geostationary(FY-2/4)and polar-orbit(FY-3)satellites.Third,the radiometric calibration techniques and accuracies of reflective solar bands,thermal infrared bands,and passive microwave bands for FY meteorological satellites are discussed.It also illustrates the latest progress of real-time calibration with the onboard calibration system and validation with different methods,including the vicarious China radiance calibration site calibration,pseudo invariant calibration site calibration,deep convective clouds calibration,and lunar calibration.Fourth,recent progress of meteorological satellite data assimilation applications and quantitative science produce are summarized at length.The main progress is in meteorological satellite data assimilation by using microwave and hyper-spectral infrared sensors in global and regional numerical weather prediction models.Lastly,the latest progress in radiative transfer,absorption and scattering calculations for satellite remote sensing is summarized,and some important research using a new radiative transfer model are illustrated. | Peng ZHANG Qifeng LU Xiuqing HU Songyan GU Lei YANG Min MIN Lin CHEN Na XU Ling Sun Wenguang BAI Gang MA Di XIAN | 2019 | Advances in Atmospheric Sciences2019，36，9： | 26 |
| 4 | Synthetically adaptive robust filtering for satellite orbit determination显示文摘The quality of the satellite orbit determination is rested on the knowledge of per-turbing forces acting on the satellite and stochastic properties of the observations, and the ability of controlling various kinds of errors. After a brief discussion on the dynamic and geometric orbit determinations, Sage adaptive filtering and robust filtering are reviewed. A new synthetically adaptive robust filtering based on a combination of robust filtering and Sage filtering is devel-oped.It is shown, by derivations and calculations, that the synthetically adaptive robust filtering for orbit determination is not only robust but also simple in calculation. It controls the effects of the outliers of tracking observations and the satellite dynamical disturbance on the parameter esti-mates of the satellite orbit. | YANG Yuanxi1 & WEN Yuanlan2 1. Xi’an Research Institute of Surveying and Mapping, Xi抋’an 710054, China 2. College of Aerospace and Material Engineering, National University of Defense Technology, Changsha 410073, China | 2004 | Science China Earth Sciences2004，47，7： | 23 |
| 5 | Estimating forest aboveground biomass using HJ-1 Satellite CCD and ICESat GLAS waveform data显示文摘The ecosystem in northeastern China and the Russian Far East is a hotspot of scientific research into the global carbon balance.Forest aboveground biomass(AGB) is an important component in the land surface carbon cycle.In this study,using forest inventory data and forest distribution data,the AGB was estimated for forest in Daxinganlin in northeastern China by combining charge-coupled device(CCD) data from the Small Satellite for Disaster and Environment Monitoring and Forecast(HJ-1) and Geoscience Laser Altimeter System(GLAS) waveform data from the Ice,Cloud and land Elevation Satellite(ICESat).The forest AGB prediction models were separately developed for different forest types in the research area at GLAS footprint level from GLAS waveform parameters and field survey plot biomass in the Changqing(CQ) Forest Center,which was calculated from forest inventory data.The resulted statistical regression models have a R2=0.68 for conifer and R2=0.71 for broadleaf forests.These models were used to estimate biomass for all GLAS footprints of forest located in the study area.All GLAS footprint biomass coupled with various spectral reflectivity parameters and vegetation indices derived from HJ-1 satellite CCD data were used in multiple regression analyses to establish biomass prediction models(R2=0.55 and R2=0.52 for needle and broadleaf respectively).Then the models were used to produce a forest AGB map for the whole study area using the HJ-1 data.Biomass data obtained from forest inventory data of the Zhuanglin(ZL) Forest Center were used as independent field measurements to validate the AGB estimated from HJ-1 CCD data(R2=0.71).About 80% of biomass samples had an error less than 20 t ha-1,and the mean error of all validation samples is 5.74 t ha-1.The pixel-level biomass map was then stratified into different biomass levels to illustrate the AGB spatial distribution pattern in this area.It was found that HJ-1 wide-swath data and GLAS waveform data can be combined to estimate forest biomass with good precision,and the biomass data can be used as input data for future carbon budget analysis. | GUO ZhiFeng1,CHI Hong1,2 & SUN GuoQing1,3 1State Key Laboratory of Remote Sensing Science,Jointly Sponsored by the Institute of Remote Sensing Applications of Chinese Academy of Sciences and Beijing Normal University,Institute of Remote Sensing Applications,Chinese Academy of Sciences,Beijing 100101,China 2Graduate University of Chinese Academy of Sciences,Beijing 100049,China 3Department of Geography University of Maryland,College Park,MD 20742,USA | 2010 | Science China Earth Sciences2010，53，S1： | 21 |
| 6 | The principle of the positioning system based on communication satellites显示文摘It is a long dream to realize the communication and navigation functionality in a satellite system in the world. This paper introduces how to establish the system, a positioning system based on communication satellites called Chinese Area Positioning System (CAPS). Instead of the typical navigation satellites, the communication satellites are configured firstly to transfer navigation signals from ground stations, and can be used to obtain service of the positioning, velocity and time, and to achieve the function of navigation and positioning. Some key technique issues should be first solved; they include the accuracy position determination and orbit prediction of the communication satellites, the measur- ing and calculation of transfer time of the signals, the carrier frequency drift in communication satellite signal transfer, how to improve the geometrical configuration of the constellation in the system, and the integration of navigation & communication. Several innovative methods are developed to make the new system have full functions of navigation and communication. Based on the development of crucial techniques and methods, the CAPS demonstration system has been designed and developed. Four communication satellites in the geosynchronous orbit (GEO) located at 87.5°E, 110.5°E, 134°E, 142°E and barometric altimetry are used in the CAPS system. The GEO satellites located at 134°E and 142°E are decommissioned GEO (DGEO) satellites. C-band is used as the navigation band. Dual frequency at C1=4143.15 MHz and C2=3826.02 MHz as well as dual codes with standard code (CA code and precision code (P code)) are adopted. The ground segment consists of five ground stations; the master station is in Lintong, Xi’an. The ground stations take a lot of responsibilities, including monitor and management of the operation of all system components, determination of the satellite position and prediction of the satellite orbit, accomplishment of the virtual atomic clock measurement, transmission and receiving navigation signals to and from each satellite. In the north, the south, the east, the west and the center of Chinese main land, the function of CAPS demonstration system is checked and measured. In cars and on board the system is also checked and measured. The results are as follow: CA-code, horizontal positioning accuracy, 15-25 m (1σ), vertical, 1-3 m; P-code, horizontal positioning accuracy, 8-10 m (1σ), vertical, 1-3 m; velocity accuracy, CA-code, 0.13-0.30 m/s, P-code, 0.15-0.17 m/s; time accuracy, CA-code, 160 ns, P-code, 13 ns; determination accuracy of orbit ≤2 m. About 20 million US $ and two years are spent for the development of demonstration. A complete CAPS system is now being established. | AI GuoXiang SHI HuLi WU HaiTao LI ZhiGang GUO Ji | 2009 | Science China(Physics,Mechanics & Astronomy)2009，52，3： | 21 |
| 7 | A new method for determination of satellite orbits by transfer显示文摘The original idea of a new method for determination of satellite orbits by transfer is from Two-Way Satellite Time and Frequency Transfer (TWSTFT). The original method is called 'determination of satellite orbit by transfer'. The method is not only for determination of satellite orbit but also for the time transfer with high accuracy and precision. The advantage is that the accuracy and the precision for determination of satellite orbit are very high and the new method is favorable for various applications. The combination of various signals disseminated and received forms various modes of satellite orbit determinations. If receivers at stations receive the own station-disseminated signals via a satellite transponder, it forms an orbit determination mode called 'receiving the own station-disseminated signals mode'. If receivers at all stations receive the signals disseminated from the master station via satellite transponders, it forms an orbit determination mode called 'receiving the master station-disseminated signals mode'. If all of receivers at stations receive all stations-disseminated signals via satellite transponders, it forms an orbit determination mode called 'receiving all stations-disseminated signals mode'. Also there are other combinations of signals for satellite orbit determination. For dif- ferent orbit determination modes with different signal combinations, their rigorous formulae of proc- essing are hereby presented in this paper. The accurate and the precise satellite orbit determination for both of the modes, 'receiving the own station-disseminated signals mode' and 'receiving the master station-disseminated signals mode' is attempted. It shows that the accuracy and precision for both of modes are nearly the same, the ranging accuracy is better than 1 cm, and the observation residuals of satellite orbit determination are better than 9 cm in the observation duration of 1 day. | LI ZhiGang YANG XuHai AI GuoXiang SI HuLi QIAO RongChuan FENG ChuGang | 2009 | Science China(Physics,Mechanics & Astronomy)2009，52，3： | 17 |
| 8 | Annual variation of sea surface height, dynamic topography and circulation in the South China Sea —— A TOPEX/Poseidon satellite altimetry study显示文摘TOPEX/Poseidon satellite altimetry data from 1993 to 1999 were used to study mean annual variation of sea surface height anomaly (SSHA) in the South China Sea (SCS) and to re-produce its climatological monthly surface dynamic topography in conjunction with historical hy-drographic data. The characters and rules of seasonal evolution of the SCS dynamic topography and its upper circulation were then discussed. Analyses indicate that annual variation of the SCS large-scale circulation could be divided into four major phases. In winter (from November to Feb-ruary), the SCS circulation is mainly controlled by double cyclonic gyres with domination of the northern gyre. Other corresponding features include the Kuroshio intrusion from the Luzon Strait and the northeastward off-shelf current in the area northwest off Kalimantan Island. The double gyre structure disassembled in spring (from March to April) when the northern gyre remains cyc-lonic, the southern gyre becomes anticyclonic, and the general circulation pattern shows a dipole. There is no obvious large-scale closed gyre inside the SCS basin in both summer (from May to July) and autumn (from August to October) when the SCS Monsoon Jet dominates the circulation, which flows northeastward across the SCS. Even so, circulation patterns of these two phases di-verse significantly. From May to July, the SCS monsoon jet flows northward near the Vietnam coast and bends eastward along the topography southeast off Hainan Island at about 18N form-ing an anticyclonic turn. It then turns northeastward after crossing the SCS. From August to Octo-ber, however, the monsoon Jet leaves the coast of Vietnam and enters interior of the basin at about 13N, and the general circulation pattern becomes cyclonic. The Kuroshio intrusion was not obvious in spring, summer and autumn. It is suggested from these observations that dynamic ad-justment of the SCS circulation starts right after the peak period of the prevailing monsoon. | 李立 许金电 靖春生 吴日升 郭小钢 | 2003 | Science China Earth Sciences2003，46，2： | 16 |
| 9 | Satellite Image Matching Method Based on Deep Convolutional Neural Network显示文摘This article focuses on the first aspect of the album of deep learning: the deep convolutional method. The traditional matching point extraction algorithm typically uses manually designed feature descriptors and the shortest distance between them to match as the matching criterion. The matching result can easily fall into a local extreme value, which causes missing of the partial matching point. Targeting this problem, we introduce a two-channel deep convolutional neural network based on spatial scale convolution, which performs matching pattern learning between images to realize satellite image matching based on a deep convolutional neural network. The experimental results show that the method can extract the richer matching points in the case of heterogeneous, multi-temporal and multi-resolution satellite images, compared with the traditional matching method. In addition, the accuracy of the final matching results can be maintained at above 90%. | Dazhao FAN Yang DONG Yongsheng ZHANG | 2019 | Journal of Geodesy and Geoinformation Science2019，2，2： | 16 |
| 10 | Impact of China’s Air Pollution Prevention and Control Action Plan on PM2.5 chemical composition over eastern China显示文摘China promulgated the Air Pollution Prevention and Control Action Plan(the Action Plan)in 2013 and developed stringent control measures to mitigate fine particulate matter(PM2.5) pollution.Here,we investigated the PM2.5 chemical composition changes over eastern China associated with the Action Plan during 2013-2017 using satellite-based PM2.5 chemical composition data derived using CMAQ simulations and satellite inputs.The PM2.5 concentrations decreased considerably during this time as a result of the reductions in all chemical species in PM2.5.The population-weighted mean concentrations over eastern China decreased from 11.1 to 6.7μgm-3 for SO42-,13.8-13.1μgm-3 for NO3-,7.4-5.8μgm-3 for NH4+,9.9-8.4μgm-3 for OM,4.6-3.8μg m-3 for BC and 12.9-9.6μg m-3 for other species in PM2.5.SO42-had the largest reduction of 40%,while NO3-had the lowest reduction of 5%,resulting in a greater fraction of NO3-and a smaller fraction of SO42-in PM2.5.Among the three key regions,Beijing-Tianjin-Hebei had the largest reduction in PM2.5 and its chemical compositions.The decrease in SO42-concentrations was in line with the reduction of SO2 emissions,and the major driver of the SO2 emission reductions was the industrial sector.The decrease in NO3 concentrations was limited because the decrease in SO2 emissions and the stable NH3 emissions facilitated the formation of NO3-from HNO3,which partially offset the reduction in NOx emissions driven by the power sector.To mitigate PM2.5 pollution more effectively,future efforts are needed to reduce NH3 emissions. | Guannan GENG Qingyang XIAO Yixuan ZHENG Dan TONG Yuxuan ZHANG Xiaoye ZHANG Qiang ZHANG Kebin HE Yang LIU | 2019 | Science China Earth Sciences2019，62，12： | 16 |
| 11 | The application of the instantaneous states reduction to the orbital monitoring of pivotal arcs of the Chang'E-1 satellite显示文摘In the Chinese lunar exploration project,the Chang'E-1 (CE-1) satellite was jointly monitored by the United S-band range and Doppler and the VLBI technique. A real-time reduction of the tracking data is realized to deduce the time series of the instantaneous state vectors (ISV) (position and velocity vec-tors) of the CE-1 satellite,and is applied to the orbital monitoring of pivotal arcs. This paper introduces this real-time data reduction method and its application to the orbital monitoring of pivotal arcs of the CE-1 satellite in order to serve as a source of criticism and reference. | LI JinLing GUO Li QIAN ZhiHan PING JinSong | 2009 | Science China(Physics,Mechanics & Astronomy)2009，52，12： | 15 |
| 12 | A multi-subwaveform parametric retracker of the radar satellite altimetric waveform and recovery of gravity anomalies over coastal oceans显示文摘The quality of satellite radar altimetric data is very important in studies of geodesy,geophysics,and oceanography.Over coastal oceans,altimeter waveforms are contaminated by the terrain and physical environments so that the accuracy of altimeter data is lower than that over open oceans.Here we develop a new multi-subwaveform parametric retracker(MSPR) to improve the quality of altimeter data for the recovery of gravity anomaly in coastal oceans.The least squares collocation method is used to recover the residual gravity anomaly over the coastal water from altimetric data.The waveform data records from Geosat/GM around Taiwan Island are practically retracked with MSPR.When compared with the Taiwan geoid height,the results retracked by MSPR are more accurate than those retracked by the well-known β-5-parmeter method and from the geophysical data records(GDRs).The gravity anomalies over Taiwan coastal waters are calculated from the retracked altimeter data with the least squares collocation.When we compared gravity anomalies computed using altimeter GDRs with the ship-borne gravity data over Taiwan coastal ocean,we found that the results from retracked data are more accurate than those from GDRs. | HWANG CheinWay | 2010 | Science China Earth Sciences2010，53，4： | 15 |
| 13 | Precise orbit determination of a maneuvered GEO satellite using CAPS ranging data显示文摘Wheel-off-loadings and orbital maneuvers of the GEO satellite result in additional accelerations to the satellite itself. Complex and difficult to model, these time varying accelerations are an important error source of precise orbit determination (POD). In most POD practices, only non-maneuver orbital arcs are treated. However, for some applications such as satellite navigation RDSS services, uninterrupted orbital ephemeris is demanded, requiring the development of POD strategies to be processed both during and after an orbital maneuver. We in this paper study the POD for a maneuvered GEO satellite, using high precision and high sampling rate ranging data obtained with Chinese Area Positioning System (CAPS). The strategy of long arc POD including maneuver arcs is studied by using telemetry data to model the maneuver thrust process. Combining the thrust and other orbital perturbations, a long arc of 6 days’ CAPS ranging data is analyzed. If the telemetry data are not available or contain significant errors, attempts are made to estimate thrusting parameters using CAPS ranging data in the POD as an alternative to properly account for the maneuver. Two strategies achieve reasonably good data fitting level in the tested arc with the maximal position difference being about 20 m. | HUANG Yong HU XiaoGong HUANG Cheng YANG QiangWen JIAO WenHai | 2009 | Science China(Physics,Mechanics & Astronomy)2009，52，3： | 13 |
| 14 | Orbit determination for geostationary satellites with the combination of transfer ranging and pseudorange data显示文摘Geostationary satellites(GEOs) play a significant role in the regional satellite navigation system.Simulation experiments show that the clock corrections could be mitigated through a single strategy or double differencing strategies for a navigation constellation,but for the mode of individual GEO orbit determination,high precision orbit and clock correction could not be obtained in the orbit determination based on the pseudorange data.A new GEO combined precise orbit determination(POD) strategy is studied in this paper,which combines pseudorange data and C-band transfer ranging data.This strategy overcomes the deficiency of C-band transfer ranging caused by limited stations and tracking time available.With the combination of transfer ranging and pseudorange data,clock corrections between the GEO and the stations can be estimated simultaneously along with orbital parameters,maintaining self-consistency between the satellite ephemeris and clock correction parameters.The error covariance analysis is conducted to illuminate the contributions from the transfer ranging data and the psudoranging data.Using data collected for a Chinese GEO satellite with 3 C-band transfer ranging stations and 4 L-band pseudorange tracking stations,POD experiments indicate that a meter-level accuracy is achievable.The root-mean-square(RMS) of the post-fit C-band ranging data is about 0.203 m,and the RMS of the post-fit pseudorange is 0.408 m.Radial component errors of the POD experiments are independently evaluated with the satellite laser ranging(SLR) data from a station in Beijing,with the residual RMS of 0.076 m.The SLR evaluation also suggests that for 2-h orbital predication,the predicted radial error is about 0.404 m,and the clock correction error is about 1.38 ns.Even for the combination of one C-band transfer ranging station and 4 pseudorange stations,POD is able to achieve a reasonable accuracy with the radial error of 0.280 m and the 2-h predicted radial error of 0.888 m.Clock synchronization between the GEO and tracking stations is achieved with an estimated accuracy of about 1.55 ns,meeting the navigation service requirements. | GUO Rui1,2,3,4,HU XiaoGong2,4,LIU Li1,WU XiaoLi1,HUANG Yong2,4 & HE Feng1 1 Beijing Global Information Application and Development Center,Beijing 100094,China 2 Shanghai Astronomical Observatory,Chinese Academy of Sciences,Shanghai 200030,China 3 Graduate University of Chinese Academy of Sciences,Beijing 100049,China 4 Space Navigation and Positioning Technology,Laboratory of Shanghai Municipal,Shanghai 200030,China | 2010 | Science China(Physics,Mechanics & Astronomy)2010，53，9： | 13 |
| 15 | IMPENDING-EARTHQUAKE SATELLITE THERMAL INFRARED AND GROUND TEMPERATUREINCREASE ANOMALIES显示文摘This note mainly discusses the relation of the impending-earthquake satellite thermal infrared anomaly with the ground temperature-increase anomaly, namely, expounds the problem if the satellite thermal infrared anomaly is the reflection of the surficial temperatureincrease anomaly caused by seismic activities on the basis of previous works about the rela- | 强祖基 徐秀登 赁常恭 | 1991 | Chinese Science Bulletin1991，36，22： | 13 |
| 16 | A FUSING TECHNIQUE WITH SATELLITE PRECIPITATION ESTIMATE AND RAINGAUGE DATA显示文摘Satellite rainfall estimate can provide rainfall information over large areas,and raingauge can provide point-based ground observations with high accuracy.With the combination of satellite and raingauge data together,the estimated rainfall fields are greatly improved.This combination method,called 'fusing technique’,is discussed in this paper,and the validation for this technique is accomplished with HUBEX IOP data. | 卢乃锰 游然 张文建 | 2004 | Acta meteorologica Sinica2004，18，2： | 12 |
| 17 | Satellite virtual atomic clock with pseudorange difference function显示文摘Satellite atomic clocks are the basis of GPS for the control of time and frequency of navigation signals. In the Chinese Area Positioning System (CAPS), a satellite navigation system without the satellite atomic clocks onboard is successfully developed. Thus, the method of time synchronization based on satellite atomic clocks in GPS is not suitable. Satellite virtual atomic clocks are used to implement satellite navigation. With the satellite virtual atomic clocks, the time at which the signals are transmitted from the ground can be delayed into the time that the signals are transmitted from the satellites and the pseudorange measuring can be fulfilled as in GPS. Satellite virtual atomic clocks can implement the navigation, make a pseudorange difference, remove the ephemeris error, and improve the accuracy of navigation positioning. They not only provide a navigation system without satellite clocks, but also a navigation system with pseudorange difference. | LI XiaoHui WU HaiTao BIAN YuJing WANG DanNi | 2009 | Science China(Physics,Mechanics & Astronomy)2009，52，3： | 11 |
| 18 | 中海达HGO软件在GPS/BDS/GLONASS静态解算的应用分析显示文摘一、引言
2012年10月20日我国成功发射了第16颗北斗卫星,至此,我国北斗导航工程区域组网顺利完成。同时,2012年12月27日,北斗卫星导航系统(BeiDou navigation satellite system.BDS)空间信号接口控制文件正式版正式公布, | 周正朝 袁本银 潘国富 | 2013 | 测绘通报2013，，3： | 11 |
| 19 | First observation of tropospheric nitrogen dioxide from the Environmental Trace Gases Monitoring Instrument onboard the GaoFen-5 satellite显示文摘The Environmental Trace Gases Monitoring Instrument(EMI)is the first Chinese satellite-borne UV–Vis spectrometer aiming to measure the distribution of atmospheric trace gases on a global scale.The EMI instrument onboard the GaoFen-5 satellite was launched on 9 May 2018.In this paper,we present the tropospheric nitrogen dioxide(NO2)vertical column density(VCD)retrieval algorithm dedicated to EMI measurement.We report the first successful retrieval of tropospheric NO_(2) VCD from the EMI instrument.Our retrieval improved the original EMI NO_(2) prototype algorithm by modifying the settings of the spectral fit and air mass factor calculations to account for the on-orbit instrumental performance changes.The retrieved EMI NO_(2) VCDs generally show good spatiotemporal agreement with the satellite-borne Ozone Monitoring Instrument and TROPOspheric Monitoring Instrument(correlation coefficient R of ~0.9,bias<50%).A comparison with ground-based MAX-DOAS(Multi-Axis Differential Optical Absorption Spectroscopy)observations also shows good correlation with an R of 0.82.The results indicate that the EMI NO_(2) retrieval algorithm derives reliable and precise results,and this algorithm can feasibly produce stable operational products that can contribute to global air pollution monitoring. | Chengxin Zhang Cheng Liu Ka Lok Chan Qihou Hu Haoran Liu Bo Li Chengzhi Xing Wei Tan Haijin Zhou Fuqi Si Jianguo Liu | 2020 | Light(Science & Applications)2020，9，1： | 11 |
| 20 | Impact of one satellite outage on ARAIM depleted constellation configurations显示文摘Advanced Receiver Autonomous Integrity Monitoring(ARAIM) is a new technology that will provide worldwide coverage of vertical guidance in aviation navigation. The ARAIM performance and improvement under depleted constellations is a practical problem that needs to be faced and researched further. It is a shortcut that improves the availability in position domain whose key idea is to replace the conventional least squares process with a non-least-squares estimator to lower the integrity risk in exchange for a slight increase in nominal position error. The contributions given in this paper include two parts: First, the impacts of one satellite outage on different constellations are analyzed and compared. The conclusion is that GPS is more sensitive and vulnerable to one satellite outage. Second, a constellation weighted ARAIM(CW-ARAIM)position estimator is proposed. The position solution is replaced by a constellation weighted average solution to eliminate the constellation difference. The new solution will move close to the constellation solutions with respect to the accuracy requirement. The simulation results under baseline GPS and Galileo dual-constellation show that the one GPS satellite outage will knock the availability from 91% to only 50%. The performance remains stable with one Galileo satellite outage. With the assistance of the CW-ARAIM method, the availability can increase from 50% to more than80% under depleted GPS configurations. Even without any satellite outage, the proposed method can effectively improve the availability from 91.29% to 98.75%. The test results under optimistic constellations further verify that a balanced constellation is more important than more satellites on orbit and the superiority of CW-ARAIM method is still effective. | Qian MENG Jianye LIU Qinghua ZENG Shaojun FENG Rui XU | 2019 | Chinese Journal of Aeronautics2019，32，4： | 11 |
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