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Almost no in situ seismic data are available for Venus; therefore, we can constrain the deep structure of this planet only from the geodetic data obtained by spacecraft. Of particular interest is Venus’s core-mantle boundary, which holds clues about the origin and evolution of this celestial body. In this study, we build a series of different mantle/core models of Venus based on several mantle composition models and compare their associated Love numbers k2 with the observed values. Due to the large uncertainty in the observed values of k2, the state of Venus’s core cannot be reliably constrained. However, the expected precision of k2 obtained by the EnVision mission will sufficiently reduce the acceptable model space and contribute to estimating the mantle viscosity structure. Based on current geodetic data, we find that the bottom of Venus’s mantle may not feature a phase transition from perovskite to post-perovskite if the FeO content of the mantle is less than 8.1 wt%; this region may be different from Earth’s D” layer. Furthermore, we find that the combination of observed k2 and Q can be used to distinguish whether the lowermost part of Venus’s mantle is a high-temperature basalt layer or a thin thermal boundary layer if observations of Q can be obtained.
Chi Xiao; Fei Li; Jianguo Yan; Michel Gregoire; Weifeng Hao; Yuji Harada; Mao Ye; Jean‐Pierre Barriot. Possible Deep Structure and Composition of Venus With Respect to the Current Knowledge From Geodetic Data. Journal of Geophysical Research: Planets 2021, 126, 1 .
AMA StyleChi Xiao, Fei Li, Jianguo Yan, Michel Gregoire, Weifeng Hao, Yuji Harada, Mao Ye, Jean‐Pierre Barriot. Possible Deep Structure and Composition of Venus With Respect to the Current Knowledge From Geodetic Data. Journal of Geophysical Research: Planets. 2021; 126 (7):1.
Chicago/Turabian StyleChi Xiao; Fei Li; Jianguo Yan; Michel Gregoire; Weifeng Hao; Yuji Harada; Mao Ye; Jean‐Pierre Barriot. 2021. "Possible Deep Structure and Composition of Venus With Respect to the Current Knowledge From Geodetic Data." Journal of Geophysical Research: Planets 126, no. 7: 1.
Mapping functions and gradients in GNSS and VLBI applications were introduced in the sixties and seventies to model the microwave propagation delays in the troposphere, and they were proven to be the perfect tools for these applications. In this work, we revisit the physical and mathematical basis of these tools in the context of meteorology and climate applications and propose an alternative approach for the wet delay part. This alternative approach is based on perturbation theory, where the base case is an exponential decay of the wet refractivity with altitude. The perturbation is modeled as a set of orthogonal functions in space and time, with the ability to separate eddy-scale variations of the wet refractivity.
Jean-Pierre Barriot; Peng Feng. Beyond Mapping Functions and Gradients. Geodetic Sciences - Theory, Applications and Recent Developments 2021, 1 .
AMA StyleJean-Pierre Barriot, Peng Feng. Beyond Mapping Functions and Gradients. Geodetic Sciences - Theory, Applications and Recent Developments. 2021; ():1.
Chicago/Turabian StyleJean-Pierre Barriot; Peng Feng. 2021. "Beyond Mapping Functions and Gradients." Geodetic Sciences - Theory, Applications and Recent Developments , no. : 1.
Jean-Pierre Barriot; Lydie Sichoix. Gravity Modeling, Theory and Computation. Encyclopedia of Solid Earth Geophysics 2021, 662 -668.
AMA StyleJean-Pierre Barriot, Lydie Sichoix. Gravity Modeling, Theory and Computation. Encyclopedia of Solid Earth Geophysics. 2021; ():662-668.
Chicago/Turabian StyleJean-Pierre Barriot; Lydie Sichoix. 2021. "Gravity Modeling, Theory and Computation." Encyclopedia of Solid Earth Geophysics , no. : 662-668.
China's lunar exploration program has developed and progressed for more than 13 years. Over this time, Precise Orbit Determination (POD) has guaranteed successful execution of the Chang'e missions, and is the basis for further scientific investigations using radio science data; for example, recovering the lunar gravity field to explore the inner structure and detect craters to study the evolutionary history of the moon. This paper briefly reviews the Chang'e series mission orbit and radio tracking measurements. We reprocessed the tracking data and comprehensively summarized the evolution of the POD accuracy and the tracking system precision from the Chang'e 1 to Chang'e 4 missions using in‐house software. Our results show a progression of the tracking station, as the first Chang'e 1 mission only reached several millimeters per second level accuracy in the Doppler measurements and several meters level accuracy for the two‐way range measurements. Later on the accuracy of Chang'e 5T1 Doppler measurements reached about 0.35 mm/s and the accuracy of the Chang'e 3 two‐way range measurements below 0.7 m. Moreover, the newest Chang'e 4 relay satellite achieved POD residuals RMS for the two‐way range less than a meter and orbital accuracy at two hundreds meter level, in contrast to meters level residual and the half‐kilometer level accuracy achieved during the Chang'e 1 mission. We can clearly see that the POD performance of the Chang'e spacecraft continuously improved. This research is a reference for future Chinese Lunar exploration missions, as well as Chinese Mars and asteroid explorations.
Shanhong Liu; Jianguo Yan; Jianfeng Cao; Mao Ye; Xie Li; Fei Li; Jean‐Pierre Barriot. Review of the Precise Orbit Determination for Chinese Lunar Exploration Projects. Earth and Space Science 2021, 8, 1 .
AMA StyleShanhong Liu, Jianguo Yan, Jianfeng Cao, Mao Ye, Xie Li, Fei Li, Jean‐Pierre Barriot. Review of the Precise Orbit Determination for Chinese Lunar Exploration Projects. Earth and Space Science. 2021; 8 (4):1.
Chicago/Turabian StyleShanhong Liu; Jianguo Yan; Jianfeng Cao; Mao Ye; Xie Li; Fei Li; Jean‐Pierre Barriot. 2021. "Review of the Precise Orbit Determination for Chinese Lunar Exploration Projects." Earth and Space Science 8, no. 4: 1.
In this paper, we assess, in the framework of Global Navigation Satellite System (GNSS) meteorology, the accuracy of GNSS propagation delays corresponding to the Saastamoinen zenith hydrostatic delay (ZHD) model and the Vienna Mapping function VMF1/VMF3 (hydrostatic and wet), with reference to radiosonde ray-tracing delays over a three-year period on 28 globally distributed sites. The results show that the Saastamoinen ZHD estimates have a mean root mean square (RMS) error of 1.7 mm with respect to the radiosonde. We also detected some seasonal signatures in these Saastamoinen ZHD estimates. This indicates that the Saastamoinen model, based on the hydrostatic assumption and the ground pressure, is insufficient to capture the full variability of the ZHD estimates over time with the accuracy needed for GNSS meteorology. Furthermore, we found that VMF3 slant hydrostatic delay (SHD) estimates outperform the corresponding VMF1 SHD estimates (equivalent SHD RMS error of 4.8 mm for VMF3 versus 7.1 mm for VMF1 at 5° elevation angle), with respect to the radiosonde SHD estimates. Unexpectedly, the situation is opposite for the VMF3 slant wet delay (SWD) estimates compared to VMF1 SWD estimates (equivalent SWD RMS error of 11.4 mm for VMF3 versus 7.0 mm for VMF1 at 5° elevation angle). Our general conclusion is that the joint approach using ZHD models and mapping functions must be revisited, at least in the framework of GNSS meteorology.
Peng Feng; Fei Li; Jianguo Yan; Fangzhao Zhang; Jean-Pierre Barriot. Assessment of the Accuracy of the Saastamoinen Model and VMF1/VMF3 Mapping Functions with Respect to Ray-Tracing from Radiosonde Data in the Framework of GNSS Meteorology. Remote Sensing 2020, 12, 3337 .
AMA StylePeng Feng, Fei Li, Jianguo Yan, Fangzhao Zhang, Jean-Pierre Barriot. Assessment of the Accuracy of the Saastamoinen Model and VMF1/VMF3 Mapping Functions with Respect to Ray-Tracing from Radiosonde Data in the Framework of GNSS Meteorology. Remote Sensing. 2020; 12 (20):3337.
Chicago/Turabian StylePeng Feng; Fei Li; Jianguo Yan; Fangzhao Zhang; Jean-Pierre Barriot. 2020. "Assessment of the Accuracy of the Saastamoinen Model and VMF1/VMF3 Mapping Functions with Respect to Ray-Tracing from Radiosonde Data in the Framework of GNSS Meteorology." Remote Sensing 12, no. 20: 3337.
We investigated the relaxation states of 11 large impact basins on Mercury based on an updated crustal thickness map, finding that the pre‐Tolstojan basins have comparable instead of varied relaxation states, suggesting that Moho temperature (TempMoho ) did not decrease substantially from ~ 4.2 to 3.8 Ga. At the same time, mantle uplift beneath the Caloris basin is the least degraded, therefore implying a sharp decrease of TempMoho ~ 3.8 Ga. These findings contrast with our thermal evolution models that predict a fast decrease of TempMoho between ~ 4.2 and 3.8 Ga. Therefore, the discrepancies in the cooling rate suggest that the relatively elevated bombardment history between ~ 4.2 to 3.8 Ga might have input additional energy to Mercury \add{and} substantially decreased the cooling rate.
Qingyun Deng; Fei Li; Jianguo Yan; Zhiyong Xiao; Mao Ye; Chi Xiao; Jean‐Pierre Barriot. The Thermal Evolution of Mercury Over the Past ∼4.2 Ga as Revealed by Relaxation States of Mantle Plugs Beneath Impact Basins. Geophysical Research Letters 2020, 47, 1 .
AMA StyleQingyun Deng, Fei Li, Jianguo Yan, Zhiyong Xiao, Mao Ye, Chi Xiao, Jean‐Pierre Barriot. The Thermal Evolution of Mercury Over the Past ∼4.2 Ga as Revealed by Relaxation States of Mantle Plugs Beneath Impact Basins. Geophysical Research Letters. 2020; 47 (20):1.
Chicago/Turabian StyleQingyun Deng; Fei Li; Jianguo Yan; Zhiyong Xiao; Mao Ye; Chi Xiao; Jean‐Pierre Barriot. 2020. "The Thermal Evolution of Mercury Over the Past ∼4.2 Ga as Revealed by Relaxation States of Mantle Plugs Beneath Impact Basins." Geophysical Research Letters 47, no. 20: 1.
Gravity modeling Explaining the variations of the external gravity field of a body in terms of its internal density variations. Applications range from oil prospecting to the deep structure of the...
Jean-Pierre Barriot; Lydie Sichoix. Gravity Modeling, Theory and Computation. Encyclopedia of Solid Earth Geophysics 2020, 1 -7.
AMA StyleJean-Pierre Barriot, Lydie Sichoix. Gravity Modeling, Theory and Computation. Encyclopedia of Solid Earth Geophysics. 2020; ():1-7.
Chicago/Turabian StyleJean-Pierre Barriot; Lydie Sichoix. 2020. "Gravity Modeling, Theory and Computation." Encyclopedia of Solid Earth Geophysics , no. : 1-7.
Shanhong Liu; Jianguo YaniD; Jianfeng Cao; Mao Ye; Xie Li; Fei Li; Jean-Pierre BarriotiD. Review of the precise orbit determination for Chinese lunar exploration projects. 2020, 1 .
AMA StyleShanhong Liu, Jianguo YaniD, Jianfeng Cao, Mao Ye, Xie Li, Fei Li, Jean-Pierre BarriotiD. Review of the precise orbit determination for Chinese lunar exploration projects. . 2020; ():1.
Chicago/Turabian StyleShanhong Liu; Jianguo YaniD; Jianfeng Cao; Mao Ye; Xie Li; Fei Li; Jean-Pierre BarriotiD. 2020. "Review of the precise orbit determination for Chinese lunar exploration projects." , no. : 1.
Traditionally, the modeling of the water vapor contents of the atmosphere is done through the estimation of precipitable water (PW)--the integrated value of the mass of water vapor over a vertical column expressed in millimeter equivalent height. This modeling method is justified by the fact that, to a high degree of approximation, the atmosphere can be seen as the stacking of horizontal layers, including water vapor, over distances larger than the height of the tropopause. Nevertheless, the cycle of the water vapor, the most prevalent of the greenhouse gases in the atmosphere, has a highly turbulent regime both in time and in space that the variations in PW cannot fully embrace. In this article, we explore the modeling method, as a series expansion in time and space, of the slant wet delays (SWDs) from one GPS receiver, as an extension of the usual modeling in zenith wet delays (ZWDs) and then PW values. In the first part, we assess, from a metrological point of view, the derivation of the SWDs computed from GPS carrier phase measurements, in the case of a very humid location, the tropical island of Tahiti, for a typical sample over the wet and dry seasons. In the second part, we introduce the series expansion of the SWDs, as seen from one GPS receiver, in terms of trigonometric functions of time and spherical harmonics of elevation and azimuth. This allows us to infer time and space correlations for the SWDs that are unreachable through the modeling of ZWD values alones. In a third part, to show that our approach also includes the zenith case, we make a comparison between the modeled SWDs in the zenith direction with wind velocities from a ground weather station and radiosonde soundings (RSs). The three main conclusions from our data case are: first, the SWDs are correlated in time by about four days, and in space, with an angular correlation distance of about 20°, both for the dry and wet seasons; second, the postfit residuals are almost uncorrelated with the SWDs from a temporal and spatial point of view, but with a diurnal component; third, there is a weak correlation between the SWDs and wind velocity, the pattern depends on the season.
Fangzhao Zhang; Jean-Pierre Barriot; Guochang Xu; Marania Hopuare. Modeling the Slant Wet Delays From One GPS Receiver as a Series Expansion With Respect to Time and Space: Theory and an Example of Application for the Tahiti Island. IEEE Transactions on Geoscience and Remote Sensing 2020, 58, 7520 -7532.
AMA StyleFangzhao Zhang, Jean-Pierre Barriot, Guochang Xu, Marania Hopuare. Modeling the Slant Wet Delays From One GPS Receiver as a Series Expansion With Respect to Time and Space: Theory and an Example of Application for the Tahiti Island. IEEE Transactions on Geoscience and Remote Sensing. 2020; 58 (11):7520-7532.
Chicago/Turabian StyleFangzhao Zhang; Jean-Pierre Barriot; Guochang Xu; Marania Hopuare. 2020. "Modeling the Slant Wet Delays From One GPS Receiver as a Series Expansion With Respect to Time and Space: Theory and an Example of Application for the Tahiti Island." IEEE Transactions on Geoscience and Remote Sensing 58, no. 11: 7520-7532.
As climate change has been of great concern worldwide for many years, addressing global climate challenges is the most significant task for humanity
Yuei-An Liou; Yuriy Kuleshov; Chung-Ru Ho; Jean-Pierre Barriot; Chyi-Tyi Lee. Preface: Earth Observations for Addressing Global Challenges. Remote Sensing 2020, 12, 841 .
AMA StyleYuei-An Liou, Yuriy Kuleshov, Chung-Ru Ho, Jean-Pierre Barriot, Chyi-Tyi Lee. Preface: Earth Observations for Addressing Global Challenges. Remote Sensing. 2020; 12 (5):841.
Chicago/Turabian StyleYuei-An Liou; Yuriy Kuleshov; Chung-Ru Ho; Jean-Pierre Barriot; Chyi-Tyi Lee. 2020. "Preface: Earth Observations for Addressing Global Challenges." Remote Sensing 12, no. 5: 841.
Since Bevis first proposed Global Positioning System (GPS) meteorology in 1992, the precipitable water (PW) estimates retrieved from Global Navigation Satellite System (GNSS) networks with high accuracy have been widely used in many meteorological applications. The proper estimation of GNSS PW can be affected by the GNSS processing strategy as well as the local geographical properties of GNSS sites. To better understand the impact of these factors, we compare PW estimates from two nearby permanent GPS stations (THTI and FAA1) in the tropical Tahiti Island, a basalt shield volcano located in the South Pacific, with a mean slope of 8% and a diameter of 30 km. The altitude difference between the two stations is 86.14 m, and their horizontal distance difference is 2.56 km. In this paper, Bernese GNSS Software Version 5.2 with precise point positioning (PPP) and Vienna mapping function 1 (VMF1) was applied to estimate the zenith tropospheric delay (ZTD), which was compared with the International GNSS Service (IGS) Final products. The meteorological parameters sourced from the European Center for Medium-Range Weather Forecasts (ECMWF) and the local weighted mean temperature ( T m ) model were used to estimate the GPS PW for three years (May 2016 to April 2019). The results show that the differences of PW between two nearby GPS stations is nearly a constant with value 1.73 mm. In our case, this difference is mainly driven by insolation differences, the difference in altitude and the wind being only second factors.
Fangzhao Zhang; Jean-Pierre Barriot; Guochang Xu; Marania Hopuare. Analysis and Comparison of GPS Precipitable Water Estimates between Two Nearby Stations on Tahiti Island. Sensors 2019, 19, 5578 .
AMA StyleFangzhao Zhang, Jean-Pierre Barriot, Guochang Xu, Marania Hopuare. Analysis and Comparison of GPS Precipitable Water Estimates between Two Nearby Stations on Tahiti Island. Sensors. 2019; 19 (24):5578.
Chicago/Turabian StyleFangzhao Zhang; Jean-Pierre Barriot; Guochang Xu; Marania Hopuare. 2019. "Analysis and Comparison of GPS Precipitable Water Estimates between Two Nearby Stations on Tahiti Island." Sensors 19, no. 24: 5578.
The Von Kármán Crater, within the South Pole-Aitken (SPA) Basin, is the landing site of China's Chang'E-4 mission. To complement the in situ exploration mission and provide initial subsurface interpretation, we applied a 3D density inversion using the Gravity Recovery and Interior Laboratory (GRAIL) gravity data. We constrain our inversion method using known geological and geophysical lunar parameters to reduce the non-uniqueness associated with gravity inversion. The 3D density models reveal vertical and lateral density variations, 2600-3200 kg/m3, assigned to the changing porosity beneath the Von Kármán Crater. We also identify two mass excess anomalies in the crust with a steep density contrast of 150 kg/m3, which were suggested to have been caused by multiple impact cratering. The anomalies from recovered near surface density models, together with the gravity derivative maps extending to the lower crust, are consistent with surface geological manifestation of excavated mantle materials from remote sensing studies. Therefore, we suggest that the density distribution of the Von Kármán Crater indicates multiple episodes of impact cratering that resulted in formation and destruction of ancient craters, with crustal reworking and excavation of mantle materials.
Chikondi Chisenga; Jianguo Yan; Jiannan Zhao; Qingyun Deng; Jean-Pierre Barriot. Density Structure of the Von Kármán Crater in the Northwestern South Pole-Aitken Basin: Initial Subsurface Interpretation of the Chang'E-4 Landing Site Region. Sensors 2019, 19, 4445 .
AMA StyleChikondi Chisenga, Jianguo Yan, Jiannan Zhao, Qingyun Deng, Jean-Pierre Barriot. Density Structure of the Von Kármán Crater in the Northwestern South Pole-Aitken Basin: Initial Subsurface Interpretation of the Chang'E-4 Landing Site Region. Sensors. 2019; 19 (20):4445.
Chicago/Turabian StyleChikondi Chisenga; Jianguo Yan; Jiannan Zhao; Qingyun Deng; Jean-Pierre Barriot. 2019. "Density Structure of the Von Kármán Crater in the Northwestern South Pole-Aitken Basin: Initial Subsurface Interpretation of the Chang'E-4 Landing Site Region." Sensors 19, no. 20: 4445.
Snowfall data are vital in calculating the surface mass balance of the Antarctic Ice Sheet (AIS), where in-situ and satellite measurements are sparse at synoptic timescales. CloudSat data are used to construct Antarctic snowfall data at synoptic timescales to compensate for the sparseness of synoptic snowfall data on the AIS and to better understand its surface mass balance. Synoptic CloudSat snowfall data are evaluated by comparison with daily snow accumulation measurements from ten automatic weather stations (AWSs) and the fifth generation of the European Centre for Medium-Range Weather Forecasts climate reanalysis (ERA5) snowfall. Synoptic snowfall data were constructed based on the CloudSat measurements within a radius of 1.41°. The results show that reconstructed CloudSat snowfall at daily and two-day resolutions cover about 28% and 29% of the area of the AIS, respectively. Daily CloudSat snowfall and AWS snow accumulation have similar trends at all stations. While influenced by stronger winds, >73.3% of extreme snow accumulation events correspond to snowfall at eight stations. Even if the CloudSat snowfall data have not been assimilated into the ERA5 dataset, the synoptic CloudSat snowfall data are almost identical to the daily ERA5 snowfall with only small biases (average root mean square error and mean absolute error < 3.9 mm/day). Agreement among the three datasets suggests that the CloudSat data can provide reliable synoptic snowfall data in most areas of the AIS. The ERA5 dataset captures a large number of extreme snowfall events at all AWSs, with capture rates varying from 56% to 88%. There are still high uncertainties in ERA5. Nevertheless, the result suggests that ERA5 can be used to represent actual snowfall events on the AIS at synoptic timescale.
Yihui Liu; Fei Li; Weifeng Hao; Jean-Pierre Barriot; Yetang Wang. Evaluation of Synoptic Snowfall on the Antarctic Ice Sheet Based on CloudSat, In-Situ Observations and Atmospheric Reanalysis Datasets. Remote Sensing 2019, 11, 1686 .
AMA StyleYihui Liu, Fei Li, Weifeng Hao, Jean-Pierre Barriot, Yetang Wang. Evaluation of Synoptic Snowfall on the Antarctic Ice Sheet Based on CloudSat, In-Situ Observations and Atmospheric Reanalysis Datasets. Remote Sensing. 2019; 11 (14):1686.
Chicago/Turabian StyleYihui Liu; Fei Li; Weifeng Hao; Jean-Pierre Barriot; Yetang Wang. 2019. "Evaluation of Synoptic Snowfall on the Antarctic Ice Sheet Based on CloudSat, In-Situ Observations and Atmospheric Reanalysis Datasets." Remote Sensing 11, no. 14: 1686.
The International GNSS Service (IGS) final products (ephemeris and clocks-correction) have made the GNSS an indispensable low-cost tool for scientific research, for example sub-daily atmospheric water vapor monitoring. In this study, we investigate if there is a systematic difference coming from the choice between the Vienna Mapping Function 1 (VMF1) and the Global Mapping Function (GMF) for the modeling of Zenith Total Delay (ZTD) estimates, as well as the Integrated Precipitable Water Vapor (IPWV) estimates that are deduced from them. As ZTD estimates cannot be fully separated from coordinate estimates, we also investigated the coordinate repeatability between subsequent measurements. For this purpose, we monitored twelve GNSS stations on a global scale, for each of the three climatic zones (polar, mid-latitudes and tropical), with four stations on each zone. We used an automated processing based on the Bernese GNSS Software Version 5.2 by applying the Precise Point Positioning (PPP) approach, L3 Ionosphere-free linear combination, 7 ̊ cutoff elevation angle and 2 h sampling. We noticed an excellent agreement with the ZTD estimates and coordinate repeatability for all the stations w.r.t to CODE (the Center for Orbit Determination in Europe) and USNO (US Naval Observatory) products, except for the Antarctic station (Davis) which shows systematic biases for the GMF related results. As a final step, we investigated the effect of using two mapping functions (VMF1 and GMF) to estimate the IPWV, w.r.t the IPWV estimates provided by the Integrated Global Radiosonde Archive (IGRA). The GPS-derived IPWV estimates are very close to the radiosonde-derived IPWV estimates, except for one station in the tropics (Tahiti).
Benachour Labib; Jianguo Yan; Jean-Pierre Barriot; Fangzhao Zhang; Peng Feng. Monitoring Zenithal Total Delays over the three different climatic zones from IGS GPS final products: A comparison between the use of the VMF1 and GMF mapping functions. Geodesy and Geodynamics 2018, 10, 93 -99.
AMA StyleBenachour Labib, Jianguo Yan, Jean-Pierre Barriot, Fangzhao Zhang, Peng Feng. Monitoring Zenithal Total Delays over the three different climatic zones from IGS GPS final products: A comparison between the use of the VMF1 and GMF mapping functions. Geodesy and Geodynamics. 2018; 10 (2):93-99.
Chicago/Turabian StyleBenachour Labib; Jianguo Yan; Jean-Pierre Barriot; Fangzhao Zhang; Peng Feng. 2018. "Monitoring Zenithal Total Delays over the three different climatic zones from IGS GPS final products: A comparison between the use of the VMF1 and GMF mapping functions." Geodesy and Geodynamics 10, no. 2: 93-99.
China is planning to land a spacecraft on the farside of the Moon, a premiere, by 2018. In essence, the traditional tracking modes, based on direct visibility, cannot operate for the lunar farside lander tracking, and therefore a relay satellite, visible at the same time by both the lander and the Earth, will be required, operating in the so-called four-way mode (Earth-relay satellite-lander-relay satellite-Earth). In this paper, we firstly give the mathematical formulation of the four-way relay tracking mode and of its partial derivatives with respect to the relevant parameters, implemented in our POD software WUDOGS (Wuhan University Deep-space Orbit determination and Gravity recovery System). In a second step, in simulation mode, we apply this relay mode to determining lander coordinates, which are absolutely needed for a sample return mission, or to add constraints on rotation models of the Moon. The results show that with Doppler measurements at a 0.1 mm/s error level, the positioning of the farside lander could be done at centimeters level (1-\(\delta\)) in the case of a circumlunar relay satellite; and at a 5 meters level (1-\(\delta\)) in the case of a Lagrange point (L2) Halo relay satellite.
Mao Ye; Fei Li; Jianguo Yan; Jean-Pierre Barriot; Weifeng Hao; Weitong Jin; Xuan Yang. The precise positioning of lunar farside lander using a four-way lander-orbiter relay tracking mode. Astrophysics and Space Science 2018, 363, 236 .
AMA StyleMao Ye, Fei Li, Jianguo Yan, Jean-Pierre Barriot, Weifeng Hao, Weitong Jin, Xuan Yang. The precise positioning of lunar farside lander using a four-way lander-orbiter relay tracking mode. Astrophysics and Space Science. 2018; 363 (11):236.
Chicago/Turabian StyleMao Ye; Fei Li; Jianguo Yan; Jean-Pierre Barriot; Weifeng Hao; Weitong Jin; Xuan Yang. 2018. "The precise positioning of lunar farside lander using a four-way lander-orbiter relay tracking mode." Astrophysics and Space Science 363, no. 11: 236.
Mons Rümker is the primary candidate region for the lunar landing mission of Chang’E-5. We propose a data processing method that combines multisource altimeter data and we developed an improved digital elevation model (DEM) of the Mons Rümker region with a horizontal resolution of 256 pixels per degree. The lunar orbiter laser altimeter (LOLA) onboard the lunar reconnaissance orbiter (LRO) acquired 884 valid orbital benchmark data with a high precision. A special crossover adjustment of 156 orbital profiles from the Chang’E-1 laser altimeter (LAM) and 149 orbital profiles from the SELenological and ENgineering Explorer (SELENE) laser altimeter (LALT) was applied. The radial residual root mean square (RMS) of the LAM was reduced from 154.83 ± 43.60 m to 14.29 ± 27.84 m and that of the LALT was decreased from 3.50 ± 5.0 m to 2.75 ± 4.4 m. We used the adjusted LAM and LALT data to fill the LOLA gaps and created the merged LOLA + LAM and LOLA + LALT DEMs. The merged LOLA + LAM DEM showed distortions because of the horizontal geolocation errors in the LAM data. The merged LOLA + LALT DEM was closer to the ground truth than the LOLA-only DEM when validated with the images of the LRO camera (LROC).
Fei Li; Chang Zhu; Weifeng Hao; Jianguo Yan; Mao Ye; Jean-Pierre Barriot; Qing Cheng; Tao Sun. An Improved Digital Elevation Model of the Lunar Mons Rümker Region Based on Multisource Altimeter Data. Remote Sensing 2018, 10, 1442 .
AMA StyleFei Li, Chang Zhu, Weifeng Hao, Jianguo Yan, Mao Ye, Jean-Pierre Barriot, Qing Cheng, Tao Sun. An Improved Digital Elevation Model of the Lunar Mons Rümker Region Based on Multisource Altimeter Data. Remote Sensing. 2018; 10 (9):1442.
Chicago/Turabian StyleFei Li; Chang Zhu; Weifeng Hao; Jianguo Yan; Mao Ye; Jean-Pierre Barriot; Qing Cheng; Tao Sun. 2018. "An Improved Digital Elevation Model of the Lunar Mons Rümker Region Based on Multisource Altimeter Data." Remote Sensing 10, no. 9: 1442.
High precision Global Positioning System (GPS) receivers, with the advantages of all-weather work and low cost, are now widely used to routinely monitor precipitable water (PW) vapor. They are so successful that the progressive phasing out of the costly and sparse in situ radio soundings (RS) is now a certainty. Nevertheless, the sub-daily to annual monitoring of high levels of the PW by GPS receivers in the tropics and the equatorial area still needs to be asserted in terms of metrology accuracy. This is the subject of this paper, which focuses on a tropical site located in mid-ocean (Tahiti). The metrology assessment was divided into two steps. Firstly, a GPS internal assessment, with an in-house processing based on the Bernese GNSS Software Version 5.2 and a comparison with the Center for Orbit Determination in Europe (CODE) products. Secondly, an external assessment, with a comparison with RS PW estimates. In contrast with previous works that only used PW estimates from the Integrated Global Radiosonde Archive (IGRA) website, we estimated the RS PW from the balloon raw data. This is especially important in tropical areas, where IGRA estimates only consider balloon measurements taken below approximately 5500 m. We show that, in our case, this threshold is one of the main sources of bias between GPS and RS estimates, and that the formula used to translate the GPS zenith wet delays (ZWD) to PW estimates also needs to be revisited for high level water vapor contents in the atmosphere.
Fangzhao Zhang; Jean-Pierre Barriot; Guochang Xu; Ta-Kang Yeh. Metrology Assessment of the Accuracy of Precipitable Water Vapor Estimates from GPS Data Acquisition in Tropical Areas: The Tahiti Case. Remote Sensing 2018, 10, 758 .
AMA StyleFangzhao Zhang, Jean-Pierre Barriot, Guochang Xu, Ta-Kang Yeh. Metrology Assessment of the Accuracy of Precipitable Water Vapor Estimates from GPS Data Acquisition in Tropical Areas: The Tahiti Case. Remote Sensing. 2018; 10 (5):758.
Chicago/Turabian StyleFangzhao Zhang; Jean-Pierre Barriot; Guochang Xu; Ta-Kang Yeh. 2018. "Metrology Assessment of the Accuracy of Precipitable Water Vapor Estimates from GPS Data Acquisition in Tropical Areas: The Tahiti Case." Remote Sensing 10, no. 5: 758.
The Martian gravity field has been improved significantly in terms of resolution, with the spatial resolution rising to 100 km and accuracy increasing up to the 110 degree and order, assisted by data collected in Mars exploration missions like MGS, MRO, and Odyssey. However, as the tracking data used for the Martian gravity field solution are from polar orbit at a low height (∼400 km), improvements in the low degree coefficients are possible with high orbiters and various inclinations. In our research, we simulate a future Chinese Mars mission, making use of its orbit, to investigate potential contributions to the Martian gravity field solution. As the Chinese Mars mission will include a lander, we investigate the same beam interferometry tracking mode for a more precise and accurate Martian gravity field solution. Our results show that this tracking mode will substantially improve the gravity field model accuracy in comparison with those models using only polar orbit data. Model accuracy is assessed by power spectrum analysis and precise orbit determination. All the simulation work are accomplished with our independent developed software. Our research will be a reference for the first Chinese Mars exploration mission.
Jianguo Yan; Xuan Yang; Weifeng Hao; Mao Ye; Fei Li; Chunkai Qu; Qingyun Deng; Weitong Jin; Jean-Pierre Barriot. A new tracking mode for improved Martian gravity field measurement. Astrophysics and Space Science 2017, 362, 236 .
AMA StyleJianguo Yan, Xuan Yang, Weifeng Hao, Mao Ye, Fei Li, Chunkai Qu, Qingyun Deng, Weitong Jin, Jean-Pierre Barriot. A new tracking mode for improved Martian gravity field measurement. Astrophysics and Space Science. 2017; 362 (12):236.
Chicago/Turabian StyleJianguo Yan; Xuan Yang; Weifeng Hao; Mao Ye; Fei Li; Chunkai Qu; Qingyun Deng; Weitong Jin; Jean-Pierre Barriot. 2017. "A new tracking mode for improved Martian gravity field measurement." Astrophysics and Space Science 362, no. 12: 236.
In this paper, we present an independent software for Mars spacecraft precise orbit determination and gravity field recovery we call the Mars Gravity Recovery and Analysis Software (MAGREAS), which is aimed to analyze tracking data from the Chinese Mars exploration mission and similar NASA and ESA Mars-related projects. The design structure, module distribution, and functions of the software are described in this manuscript. A detailed cross validation with the mature precise orbit determination platform Geodyn-II was done. Additionally, we use MAGREAS to process the MEX orbital tracking data with two-way and three-way tracking modes separately. Measurement residuals and the difference from the reconstructed ephemeris provided by Royal Observatory of Belgium indicate that our software is reliable. In addition to describe of our software and validate with Geodyn-II, we give a simulation case close to Chinese Mars exploration mission to indicate the application of our software. We present a simulation of a four-way tracking mode between Earth tracking station, Mars orbiter, and Mars lander to validate the effectiveness of our MAGREAS-based approach for Mars orbiter determination and lander positioning. Experimental results show that our proposed tracking mode significantly improves positioning accuracy. This work will provide a reference for the design of the Chinese Mars exploration mission as well as for the processing of Chinese Mars mission orbital tracking data.
Jianguo Yan; Weitong Jin; Jean-Pierre Barriot; Xuan Yang; Mao Ye; Fei Li. Independent Mars spacecraft precise orbit determination software development and its applications. Astrophysics and Space Science 2017, 362, 1 .
AMA StyleJianguo Yan, Weitong Jin, Jean-Pierre Barriot, Xuan Yang, Mao Ye, Fei Li. Independent Mars spacecraft precise orbit determination software development and its applications. Astrophysics and Space Science. 2017; 362 (7):1.
Chicago/Turabian StyleJianguo Yan; Weitong Jin; Jean-Pierre Barriot; Xuan Yang; Mao Ye; Fei Li. 2017. "Independent Mars spacecraft precise orbit determination software development and its applications." Astrophysics and Space Science 362, no. 7: 1.
The tidal potential generated by the Moon and the Sun modulates the gravity vector in amplitude (g) and orientation (deflection of the vertical). The solid Earth reacts to the applied forces, which are inducing vertical and horizontal displacements associated with an additional change of potential. The proportionality between reaction and excitation is measured through the so-called Love and Shida numbers h, k, and l. Polar motion is generating the so-called “Pole Tide” with annual and Chandler period. The fluid masses are also submitted to ocean tides and radiation tides, also called atmospheric tides. A general approach of Earth Tides was first proposed by Melchior (1983). Several recent good monographies about Earth Tides already exist, and we refer to Wahr (1995), Wilhelm et al. (1997), Cartwright (1999), and Agnew (2007) for an extended coverage of the subject. In this short introduction, we try to address what Earth Tides are and all the applications of Earth ...
Jean-Pierre Barriot; Bernard Ducarme. Tidal Effects. Encyclopedia of Solid Earth Geophysics 2016, 1 -8.
AMA StyleJean-Pierre Barriot, Bernard Ducarme. Tidal Effects. Encyclopedia of Solid Earth Geophysics. 2016; ():1-8.
Chicago/Turabian StyleJean-Pierre Barriot; Bernard Ducarme. 2016. "Tidal Effects." Encyclopedia of Solid Earth Geophysics , no. : 1-8.