Journal articles: 'GRACE Satellite'

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Simonov, Konstantin, and Alexander Matsulev. "Comparative analysis and interpretation of grace and grace-fo data." Informatization and communication 4 (November 2020): 101–6. http://dx.doi.org/10.34219/2078-8320-2020-11-4-101-106.

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The study is devoted to the analysis of the features of the change in the Equivalent Water Height (EWH) parameter over the geoid based on satellite measurements of space systems. The study used the GRACE and GRACE-FO satellite data archive. The assessment was carried out on Earth as a whole, including land areas and the World Ocean. Interpretation of the anomalous state of the geoenvironment is performed using digital maps of the spatial distribution of the EWH parameter based on the histogram approach and correlation analysis. Also, a comparative analysis of the studied data from the GRACE mission and data from the new GRACE-FO satellite system launched into orbit in the summer of 2018 was carried out.

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Darbeheshti, Neda, Henry Wegener, Vitali Müller, Majid Naeimi, Gerhard Heinzel, and Martin Hewitson. "Instrument data simulations for GRACE Follow-on: observation and noise models." Earth System Science Data 9, no. 2 (November 17, 2017): 833–48. http://dx.doi.org/10.5194/essd-9-833-2017.

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Abstract. The Gravity Recovery and Climate Experiment (GRACE) mission has yielded data on the Earth's gravity field to monitor temporal changes for more than 15 years. The GRACE twin satellites use microwave ranging with micrometre precision to measure the distance variations between two satellites caused by the Earth's global gravitational field. GRACE Follow-on (GRACE-FO) will be the first satellite mission to use inter-satellite laser interferometry in space. The laser ranging instrument (LRI) will provide two additional measurements compared to the GRACE mission: interferometric inter-satellite ranging with nanometre precision and inter-satellite pointing information. We have designed a set of simulated GRACE-FO data, which include LRI measurements, apart from all other GRACE instrument data needed for the Earth's gravity field recovery. The simulated data files are publicly available via https://doi.org/10.22027/AMDC2 and can be used to derive gravity field solutions like from GRACE data. This paper describes the scientific basis and technical approaches used to simulate the GRACE-FO instrument data.

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Guo, Nan-nan, Xu-hua Zhou, Kai Li, and Bin Wu. "Research on the impact factors of GRACE precise orbit determination by dynamic method." Journal of Applied Geodesy 12, no. 3 (July 26, 2018): 249–57. http://dx.doi.org/10.1515/jag-2018-0008.

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Abstract With the successful use of GPS-only-based POD (precise orbit determination), more and more satellites carry onboard GPS receivers to support their orbit accuracy requirements. It provides continuous GPS observations in high precision, and becomes an indispensable way to obtain the orbit of LEO satellites. Precise orbit determination of LEO satellites plays an important role for the application of LEO satellites. Numerous factors should be considered in the POD processing. In this paper, several factors that impact precise orbit determination are analyzed, namely the satellite altitude, the time-variable earth’s gravity field, the GPS satellite clock error and accelerometer observation. The GRACE satellites provide ideal platform to study the performance of factors for precise orbit determination using zero-difference GPS data. These factors are quantitatively analyzed on affecting the accuracy of dynamic orbit using GRACE observations from 2005 to 2011 by SHORDE software. The study indicates that: (1) with the altitude of the GRACE satellite is lowered from 480 km to 460 km in seven years, the 3D (three-dimension) position accuracy of GRACE satellite orbit is about 3∼4 cm based on long spans data; (2) the accelerometer data improves the 3D position accuracy of GRACE in about 1 cm; (3) the accuracy of zero-difference dynamic orbit is about 6 cm with the GPS satellite clock error products in 5 min sampling interval and can be raised to 4 cm, if the GPS satellite clock error products with 30 s sampling interval can be adopted. (4) the time-variable part of earth gravity field model improves the 3D position accuracy of GRACE in about 0.5∼1.5 cm. Based on this study, we quantitatively analyze the factors that affect precise orbit determination of LEO satellites. This study plays an important role to improve the accuracy of LEO satellites orbit determination.

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Guo, Xiang, and Qile Zhao. "A New Approach to Earth’s Gravity Field Modeling Using GPS-Derived Kinematic Orbits and Baselines." Remote Sensing 11, no. 14 (July 21, 2019): 1728. http://dx.doi.org/10.3390/rs11141728.

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Earth’s gravity field recovery from GPS observations collected by low earth orbiting (LEO) satellites is a well-established technique, and kinematic orbits are commonly used for that purpose. Nowadays, more and more satellites are flying in close formations. The GPS-derived kinematic baselines between them can reach millimeter precision, which is more precise than the centimeter-level kinematic orbits. Thus, it has long been expected that the more precise kinematic baselines can deliver better gravity field solutions. However, this expectation has not been met yet in practice. In this study, we propose a new approach to gravity field modeling, in which kinematic orbits of the reference satellite and baseline vectors between the reference satellite and its accompanying satellite are jointly inverted. To validate the added value, data from the Gravity Recovery and Climate Experiment (GRACE) satellite mission are used. We derive kinematic orbits and inter-satellite baselines of the twin GRACE satellites from the GPS data collected in the year of 2010. Then two sets of monthly gravity field solutions up to degree and order 60 are produced. One is derived from kinematic orbits of the twin GRACE satellites (‘orbit approach’). The other is derived from kinematic orbits of GRACE A and baseline vectors between GRACE A and B (‘baseline approach’). Analysis of observation postfit residuals shows that noise in the kinematic baselines is notably lower than the kinematic orbits by 50, 47 and 43% for the along-track, cross-track and radial components, respectively. Regarding the gravity field solutions, analysis in the spectral domain shows that noise of the gravity field solutions beyond degree 10 can be significantly reduced when the baseline approach is applied, with cumulative errors up to degree 60 being reduced by 34%, when compared to the orbit approach. In the spatial domain, the recovered mass changes with the baseline approach are more consistent with those inferred from the K-Band Ranging based solutions. Our results demonstrate that the proposed baseline approach is able to provide better gravity field solutions than the orbit approach. The findings may facilitate, among others, bridging the gap between GRACE and GRACE Follow-On satellite mission.

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Wickert, J., G. Beyerle, R. König, S. Heise, L. Grunwaldt, G. Michalak, Ch Reigber, and T. Schmidt. "GPS radio occultation with CHAMP and GRACE: A first look at a new and promising satellite configuration for global atmospheric sounding." Annales Geophysicae 23, no. 3 (March 30, 2005): 653–58. http://dx.doi.org/10.5194/angeo-23-653-2005.

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Abstract. CHAMP (CHAllenging Minisatellite Payload) and GRACE (Gravity Recovery And Climate Experiment) formed a satellite configuration for precise atmospheric sounding during the first activation of the GPS (Global Positioning System) radio occultation experiment aboard GRACE on 28 and 29 July 2004. 338 occultations were recorded aboard both satellites, providing globally distributed vertical profiles of refractivity, temperature and specific humidity. The combined set of CHAMP and GRACE profiles shows excellent agreement with meteorological analysis. Almost no refractivity bias is observed between 5 and 30km, the standard deviation is between 1 and 2% within this altitude interval. The GRACE satellite clock stability is significantly improved in comparison with CHAMP. This allows for the application of a zero difference technique for precise analysis of the GRACE occultation data.

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6

Han, S. C., C. Jekeli, and C. K. Shum. "Static and temporal gravity field recovery using grace potential difference observables." Advances in Geosciences 1 (June 17, 2003): 19–26. http://dx.doi.org/10.5194/adgeo-1-19-2003.

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Abstract. The gravity field dedicated satellite missions like CHAMP, GRACE, and GOCE are supposed to map the Earth’s global gravity field with unprecedented accuracy and resolution. New models of Earth’s static and time-variable gravity field will be available every month as one of the science products from GRACE. Here we present an alternative method to estimate the gravity field efficiently using the in situ satellite-to-satellite observations at the altitude and show results on static as well as temporal gravity field recovery. Considering the energy relation between the kinetic energy of the satellite and the gravitational potential, the disturbing potential difference observations can be computed from the orbital parameter vectors in the inertial frame, using the high-low GPS-LEO GPS tracking data, the low-low satelliteto- satellite GRACE measurements, and data from 3-axis accelerometers (Jekeli, 1999). The disturbing potential observation also includes other potentials due to tides, atmosphere, other modeled signals (e.g. N-body) and the geophysical fluid signals (hydrological and oceanic mass variations), which should be recoverable from GRACE mission with a monthly resolution. The simulation results confirm that monthly geoid accuracy is expected to be a few cm with the 160 km resolution (up to degree and order 120) once other corrections are made accurately. The time-variable geoids (ocean and ground water mass) might be recovered with a noise-to-signal ratio of 0.1 with the resolution of 800 km every month assuming no temporal aliasing.Key words. GRACE mission, Energy integral, Geopotential, Satellite-to-satellite tracking, Temporal gravity field

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Wiese, D. N., B. Killett, M. M. Watkins, and D. ‐N Yuan. "Antarctic tides from GRACE satellite accelerations." Journal of Geophysical Research: Oceans 121, no. 5 (May 2016): 2874–86. http://dx.doi.org/10.1002/2015jc011488.

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8

Zhong, Luping, Krzysztof Sośnica, Matthias Weigelt, Bingshi Liu, and Xiancai Zou. "Time-Variable Gravity Field from the Combination of HLSST and SLR." Remote Sensing 13, no. 17 (September 2, 2021): 3491. http://dx.doi.org/10.3390/rs13173491.

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The Earth’s time-variable gravity field is of great significance to study mass change within the Earth’s system. Since 2002, the NASA-DLR Gravity Recovery and Climate Experiment (GRACE) and its successor GRACE follow-on mission provide observations of monthly changes in the Earth gravity field with unprecedented accuracy and resolution by employing low-low satellite-to-satellite tracking (LLSST) measurements. In addition to LLSST, monthly gravity field models can be acquired from satellite laser ranging (SLR) and high-low satellite-to-satellite tracking (HLSST). The monthly gravity field solutions HLSST+SLR were derived by combining HLSST observations of low earth orbiting (LEO) satellites with SLR observations of geodetic satellites. Bandpass filtering was applied to the harmonic coefficients of HLSST+SLR solutions to reduce noise. In this study, we analyzed the performance of the monthly HLSST+SLR solutions in the spectral and spatial domains. The results show that: (1) the accuracies of HLSST+SLR solutions are comparable to those from GRACE for coefficients below degree 10, and significantly improved compared to those of SLR-only and HLSST-only solutions; (2) the effective spatial resolution could reach 1000 km, corresponding to the spherical harmonic coefficient degree 20, which is higher than that of the HLSST-only solutions. Compared with the GRACE solutions, the global mass redistribution features and magnitudes can be well identified from HLSST+SLR solutions at the spatial resolution of 1000 km, although with much noise. In the applications of regional mass recovery, the seasonal variations over the Amazon Basin and the long-term trend over Greenland derived from HLSST+SLR solutions truncated to degree 20 agree well with those from GRACE solutions without truncation, and the RMS of mass variations is 282 Gt over the Amazon Basin and 192 Gt in Greenland. We conclude that HLSST+SLR can be an alternative option to estimate temporal changes in the Earth gravity field, although with far less spatial resolution and lower accuracy than that offered by GRACE. This approach can monitor the large-scale mass transport during the data gaps between the GRACE and the GRACE follow-on missions.

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9

Eshagh, M., M. Abdollahzadeh, and M. Najafi-Alamdari. "Simplification of Geopotential Perturbing Force Acting on A Satellite." Artificial Satellites 43, no. 2 (January 1, 2008): 45–64. http://dx.doi.org/10.2478/v10018-009-0006-7.

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Simplification of Geopotential Perturbing Force Acting on A SatelliteOne of the aspects of geopotential models is orbit integration of satellites. The geopotential acceleration has the largest influence on a satellite with respect to the other perturbing forces. The equation of motion of satellites is a second-order vector differential equation. These equations are further simplified and developed in this study based on the geopotential force. This new expression is much simpler than the traditional one as it does not derivatives of the associated Legendre functions and the transformations are included in the equations. The maximum degree and order of the geopotential harmonic expansion must be selected prior to the orbit integration purposes. The values of the maximum degree and order of these coefficients depend directly on the satellite's altitude. In this article, behaviour of orbital elements of recent geopotential satellites, such as CHAMP, GRACE and GOCE is considered with respect to the different degree and order of geopotential coefficients. In this case, the maximum degree 116, 109 and 175 were derived for the Earth gravitational field in short arc orbit integration of the CHAMP, GRACE and GOCE, respectively considering millimeter level in perturbations.

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10

Meyer, Ulrich, Krzysztof Sosnica, Daniel Arnold, Christoph Dahle, Daniela Thaller, Rolf Dach, and Adrian Jäggi. "SLR, GRACE and Swarm Gravity Field Determination and Combination." Remote Sensing 11, no. 8 (April 22, 2019): 956. http://dx.doi.org/10.3390/rs11080956.

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Satellite gravimetry allows for determining large scale mass transport in the system Earth and to quantify ice mass change in polar regions. We provide, evaluate and compare a long time-series of monthly gravity field solutions derived either by satellite laser ranging (SLR) to geodetic satellites, by GPS and K-band observations of the GRACE mission, or by GPS observations of the three Swarm satellites. While GRACE provides gravity signal at the highest spatial resolution, SLR sheds light on mass transport in polar regions at larger scales also in the pre- and post-GRACE era. To bridge the gap between GRACE and GRACE Follow-On, we also derive monthly gravity fields using Swarm data and perform a combination with SLR. To correctly take all correlations into account, this combination is performed on the normal equation level. Validating the Swarm/SLR combination against GRACE during the overlapping period January 2015 to June 2016, the best fit is achieved when down-weighting Swarm compared to the weights determined by variance component estimation. While between 2014 and 2017 SLR alone slightly overestimates mass loss in Greenland compared to GRACE, the combined gravity fields match significantly better in the overlapping time period and the RMS of the differences is reduced by almost 100 Gt. After 2017, both SLR and Swarm indicate moderate mass gain in Greenland.

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11

Pivetta, T., C. Braitenberg, and D. F. Barbolla. "Geophysical Challenges for Future Satellite Gravity Missions: Assessing the Impact of MOCASS Mission." Pure and Applied Geophysics 178, no. 6 (June 2021): 2223–40. http://dx.doi.org/10.1007/s00024-021-02774-3.

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AbstractThe GRACE/GRACE-FO satellites have observed large scale mass changes, contributing to the mass budget calculation of the hydro-and cryosphere. The scale of the observable mass changes must be in the order of 300 km or bigger to be resolved. Smaller scale glaciers and hydrologic basins significantly contribute to the closure of the water mass balance, but are not detected with the present spatial resolution of the satellite. The challenge of future satellite gravity missions is to fill this gap, providing higher temporal and spatial resolution. We assess the impact of a geodetic satellite mission carrying on board a cold atom interferometric gradiometer (MOCASS: Mass Observation with Cold Atom Sensors in Space) on the resolution of simulated geophysical phenomena, considering mass changes in the hydrosphere and cryosphere. Moreover, we consider mass redistributions due to seamounts and tectonic movements, belonging to the solid earth processes. The MOCASS type satellite is able to recover 50% smaller deglaciation rates over a mountain range as the High Mountains of Asia compared to GRACE, and to detect the mass of 60% of the cumulative number of glaciers, an improvement respect to GRACE which detects less than 20% in the same area. For seamounts a significantly smaller mass eruption could be detected with respect to GRACE, reaching a level of mass detection of a submarine basalt eruption of 1.6 109 m3. This mass corresponds to the eruption of Mount Saint Helens. The simulations demonstrate that a MOCASS type mission would significantly improve the resolution of mass changes respect to existing geodetic satellite missions.

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12

Mayer-Gürr, T., R. Savcenko, W. Bosch, I. Daras, F. Flechtner, and Ch Dahle. "Ocean tides from satellite altimetry and GRACE." Journal of Geodynamics 59-60 (September 2012): 28–38. http://dx.doi.org/10.1016/j.jog.2011.10.009.

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13

Godah, Walyeldeen, Jagat Dwipendra Ray, Malgorzata Szelachowska, and Jan Krynski. "The Use of National CORS Networks for Determining Temporal Mass Variations within the Earth’s System and for Improving GRACE/GRACE-FO Solutions." Remote Sensing 12, no. 20 (October 15, 2020): 3359. http://dx.doi.org/10.3390/rs12203359.

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Temporal mass variations within the Earth’s system can be detected on a regional/global scale using GRACE (Gravity Recovery and Climate Experiment) and GRACE Follow-On (GRACE-FO) satellite missions’ data, while GNSS (Global Navigation Satellite System) data can be used to detect those variations on a local scale. The aim of this study is to investigate the usefulness of national GNSS CORS (Continuously Operating Reference Stations) networks for the determination of those temporal mass variations and for improving GRACE/GRACE-FO solutions. The area of Poland was chosen as a study area. Temporal variations of equivalent water thickness ΔEWT and vertical deformations of the Earth’s surface Δh were determined at the sites of the ASG-EUPOS (Active Geodetic Network of the European Position Determination System) CORS network using GRACE/GRACE-FO-based GGMs and GNSS data. Moreover, combined solutions of ΔEWT were developed by combining ΔEWT obtained from GNSS data with the corresponding ones determined from GRACE satellite mission data. Strong correlations (correlation coefficients ranging from 0.6 to 0.9) between detrended Δh determined from GRACE/GRACE-FO satellite mission data and the corresponding ones from GNSS data were observed at 93% of the GNSS stations investigated. Furthermore, for the determination of temporal mass variations, GNSS data from CORS network stations provide valuable information complementary to GRACE satellite mission data.

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Gurzadyan, V. G., I. Ciufolini, A. Paolozzi, A. L. Kashin, H. G. Khachatryan, S. Mirzoyan, and G. Sindoni. "Satellites testing general relativity: Residuals versus perturbations." International Journal of Modern Physics D 26, no. 05 (April 2017): 1741020. http://dx.doi.org/10.1142/s0218271817410206.

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Laser ranging satellites have proved their efficiency for high precision testing of the effect of frame-dragging, one of the remarkable predictions of General Relativity. The analysis of the randomness properties of the residuals of LAGEOS and LAGEOS 2 satellites reveals the role of the thermal thrust — Yarkovsky effect — on the satellite which was in the orbit for longer period (LAGEOS). We also compute Earth’s tidal modes affecting the satellite LARES. The recently obtained 5% accuracy limit reached for the frame dragging effect based on the 3.5 year data of LARES analyzed together with those of LAGEOS satellites and using the Earth gravity model of GRACE satellite, is also represented.

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Tkachenko, N. S., and I. V. Lygin. "GRACE application for geological and geographical problems." Moscow University Bulletin. Series 4. Geology, no. 2 (April 28, 2017): 3–7. http://dx.doi.org/10.33623/0579-9406-2017-2-3-7.

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In this article we provide the literature review of the geological and geographical problems which were successfully solved due to application of GRACE satellite mission data. GRACE (Gravity Recovery And Climate Experiment) is gravitational satellite mission the purpose of which is precise mapping of variations of Earth’s gravity field. The data has high resolution that gives the opportunity to solve a lot of geological and geographical problems.

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Khaki, M., E. Forootan, M. Kuhn, J. Awange, L. Longuevergne, and Y. Wada. "Efficient basin scale filtering of GRACE satellite products." Remote Sensing of Environment 204 (January 2018): 76–93. http://dx.doi.org/10.1016/j.rse.2017.10.040.

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17

Featherstone, W. E. "Augmentation of AUSGeoid98 with Grace satellite gravity data." Journal of Spatial Science 52, no. 2 (December 2007): 75–86. http://dx.doi.org/10.1080/14498596.2007.9635124.

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18

Lakshmi, Venkat. "Beyond GRACE : Using Satellite Data for Groundwater Investigations." Groundwater 54, no. 5 (August 4, 2016): 615–18. http://dx.doi.org/10.1111/gwat.12444.

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Roh, Kyoung-Min, and Yoola Hwang. "Performance Comparison of KOMPSAT-5 Precision Orbit Determination with GRACE." International Journal of Aerospace Engineering 2020 (February 27, 2020): 1–11. http://dx.doi.org/10.1155/2020/7358286.

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The Korean Multipurpose Satellite-5 (KOMPSAT-5) launched on 22 August 2013 was equipped with a global positioning system (GPS) receiver for precision orbit determination (POD). Even though the GPS receiver of KOMPSAT-5 shares the same heritage as the BlackJack receiver onboard in Gravity Recovery and Climate Experiment (GRACE) satellites, KOMPSAT-5 has a lower orbital position accuracy (~10 cm) compared with GRACE (~2 cm). The reduced dynamic and kinematic methods are applied for POD of KOMPSAT-5 and GRACE to investigate the GPS observation quality due to the satellite operation concept and hardware design. The results are analyzed in terms of the number of observations and their spatial distribution, GPS signal quality, and orbital position accuracies. The results show that the frequent attitude maneuvers of KOMPSAT-5 affect the quality of the GPS signals and solutions obtained from the kinematic method compared with that determined from the reduced-dynamic method. The onboard patch GPS antenna installed in KOMPSAT-5 and its geometrical position resulted in more erratic measurement residuals by 140% compared with the choke ring antenna of GRACE. The POD accuracy is dependent on the hardware design and regular attitude tilting for the synthetic aperture radar (SAR) imaging even though the same GPS receiver performances.

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Rybas, O. V., and G. Z. Gil’manova. "Statistical relationship between GRACE satellite data and total global solar radiation values." Sovremennye problemy distantsionnogo zondirovaniya Zemli iz kosmosa 15, no. 2 (2018): 263–66. http://dx.doi.org/10.21046/2070-7401-2018-15-2-263-266.

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Wang, Zhengtao, Kunjun Tian, Fupeng Li, Si Xiong, Yu Gao, Lingxuan Wang, and Bingbing Zhang. "Using Swarm to Detect Total Water Storage Changes in 26 Global Basins (Taking the Amazon Basin, Volga Basin and Zambezi Basin as Examples)." Remote Sensing 13, no. 14 (July 6, 2021): 2659. http://dx.doi.org/10.3390/rs13142659.

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The Gravity Recovery and Climate Experiment (GRACE) satellite provides time-varying gravity field models that can detect total water storage change (TWSC) from April 2002 to June 2017, and its second-generation satellite, GRACE Follow-On (GRACE-FO), provides models from June 2018, so there is a one year gap. Swarm satellites are equipped with Global Positioning System (GPS) receivers, which can be used to recover the Earth’s time-varying gravitational field. Swarm’s time-varying gravitational field models (from December 2013 to June 2018) were solved by the International Combination Service for Time-variable Gravity Field Solutions (COST-G) and the Astronomical Institute of the Czech Academy of Sciences (ASI). On a timely scale, Swarm has the potential to fill the gap between the two generations of GRACE satellites. In this paper, using 26 global watersheds as the study area, first, we explored the optimal data processing strategy for Swarm and then obtained the Swarm-TWSC of each watershed based on the optimal results. Second, we evaluated Swarm’s accuracy in detecting regional water storage variations, analyzed the reasons for its superior and inferior performance in different regions, and systematically explored its potential in detecting terrestrial water storage changes in land areas. Finally, we constructed the time series of terrestrial water storage changes from 2002 to 2019 by combining GRACE, Swarm, and GRACE-FO for the Amazon, Volga, and Zambezi Basins. The results show that the optimal data processing strategy of Swarm is different from that of GRACE. The optimal results of Swarm-TWSC were explored in 26 watersheds worldwide; its accuracy is related to the area size, runoff volume, total annual mass change, and instantaneous mass change of the watershed itself, among which the latter is the main factor affecting Swarm-TWSC. Knowledge of the Swarm-TWSC of 26 basins constructed in this paper is important to study long-term water storage changes in basins.

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Pail, R., H. Goiginger, W. D. Schuh, E. Höck, J. M. Brockmann, T. Fecher, T. Gruber, et al. "Combined satellite gravity field modelGOCO01Sderived from GOCE and GRACE." Geophysical Research Letters 37, no. 20 (October 2010): n/a. http://dx.doi.org/10.1029/2010gl044906.

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ZHOU, Xu-Hua, Houtse HSU, Bin WU, Bi-Bo PENG, and Yang LU. "Earth's Gravity Field Derived from Grace Satellite Tracking Data." Chinese Journal of Geophysics 49, no. 3 (May 2006): 651–56. http://dx.doi.org/10.1002/cjg2.879.

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Flury, Jakob, Srinivas Bettadpur, and Byron D. Tapley. "Precise accelerometry onboard the GRACE gravity field satellite mission." Advances in Space Research 42, no. 8 (October 2008): 1414–23. http://dx.doi.org/10.1016/j.asr.2008.05.004.

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Zheng, Wei, Houtse Hsu, Min Zhong, and Meijuan Yun. "Requirements Analysis for Future Satellite Gravity Mission Improved-GRACE." Surveys in Geophysics 36, no. 1 (September 10, 2014): 87–109. http://dx.doi.org/10.1007/s10712-014-9306-y.

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Bandikova, Tamara, Jakob Flury, and Ung-Dai Ko. "Characteristics and accuracies of the GRACE inter-satellite pointing." Advances in Space Research 50, no. 1 (July 2012): 123–35. http://dx.doi.org/10.1016/j.asr.2012.03.011.

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Matsulev, A. N., and K. V. Simonov. "Interpretation of grace system data for solving geodynamic monitoring tasks." Informatization and communication, no. 2 (April 30, 2020): 67–72. http://dx.doi.org/10.34219/2078-8320-2020-11-2-67-72.

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The study is devoted to the analysis of the features of the change in the EWH (Equivalent Water Height) parameter over the geoid by satellite measurements of the GRACE space system in various regions of the World Ocean. A GRACE satellite data archive has been created. The perturbed state of the geomedium is interpreted using digital maps of the spatial distribution of the EWH parameter based on the histogram approach and correlation analysis.

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Swenson, Sean, and John Wahr. "Estimating Large-Scale Precipitation Minus Evapotranspiration from GRACE Satellite Gravity Measurements." Journal of Hydrometeorology 7, no. 2 (April 1, 2006): 252–70. http://dx.doi.org/10.1175/jhm478.1.

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Abstract Currently, observations of key components of the earth's large-scale water and energy budgets are sparse or even nonexistent. One key component, precipitation minus evapotranspiration (P − ET), remains largely unmeasured due to the absence of observations of ET. Precipitation minus evapotranspiration describes the flux of water between the atmosphere and the earth's surface, and therefore provides important information regarding the interaction of the atmosphere with the land surface. In this paper, large-scale changes in continental water storage derived from satellite gravity data from the Gravity Recovery and Climate Experiment (GRACE) project are combined with river discharge data to obtain estimates of areally averaged P − ET. After constructing an equation describing the large-scale terrestrial water balance reflecting the temporal sampling of GRACE water storage estimates, GRACE-derived P − ET estimates are compared to those obtained from a reanalysis dataset [NCEP/Department of Energy (DOE) reanalysis-2] and a land surface model driven with observation-based forcing [Global Land Data Assimilation System (GLDAS)/Noah] for two large U.S. river basins. GRACE-derived P − ET compares quite favorably with the reanalysis-2 output, while P − ET from the Noah model shows significant differences. Because the uncertainties in the GRACE results can be computed rigorously, this comparison may be considered as a validation of the models. In addition to showing how GRACE P − ET estimates may be used to validate model output, the accuracy of GRACE estimates of both the seasonal cycle and the monthly averaged rate of P − ET is examined. Finally, the potential for estimating seasonal evapotranspiration is demonstrated by combining GRACE seasonal P − ET estimates with independent estimates of the seasonal cycle of precipitation.

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Gao, Chao, Shuanggen Jin, and Liangliang Yuan. "Ionospheric Responses to the June 2015 Geomagnetic Storm from Ground and LEO GNSS Observations." Remote Sensing 12, no. 14 (July 9, 2020): 2200. http://dx.doi.org/10.3390/rs12142200.

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Geomagnetic storms are extreme space weather events, which have considerable impacts on the ionosphere and power transmission systems. In this paper, the ionospheric responses to the geomagnetic storm on 22 June 2015, are analyzed from ground-based and satellite-based Global Navigation Satellite System (GNSS) observations as well as observational data of digital ionosondes, and the main physical mechanisms of the ionospheric disturbances observed during the geomagnetic storm are discussed. Salient positive and negative storms are observed from vertical total electron content (VTEC) based on ground-based GNSS observations at different stages of the storm. Combining topside observations of Low-Earth-Orbit (LEO) satellites (GRACE and MetOp satellites) with different orbital altitudes and corresponding ground-based observations, the ionospheric responses above and below the orbits are studied during the storm. To obtain VTEC from the slant TEC between Global Positioning System (GPS) and LEO satellites, we employ a multi-layer mapping function, which can effectively reduce the overall error caused by the single-layer geometric assumption where the horizontal gradient of the ionosphere is not considered. The results show that the topside observations of the GRACE satellite with a lower orbit can intuitively detect the impact caused by the fluctuation of the F2 peak height (hmF2). At the same time, the latitude range corresponding to the peak value of the up-looking VTEC on the event day becomes wider, which is the precursor of the Equatorial Ionization Anomaly (EIA). However, no obvious response is observed in the up-looking VTEC from MetOp satellites with higher orbits, which indicates that the VTEC responses to the geomagnetic storm mainly take place below the orbit of MetOp satellites.

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Sharifi, M. A., M. R. Seif, and M. A. Hadi. "A Comparison Between Numerical Differentiation and Kalman Filtering for a Leo Satellite Velocity Determination." Artificial Satellites 48, no. 3 (September 1, 2013): 103–10. http://dx.doi.org/10.2478/arsa-2013-0009.

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Abstract The kinematic orbit is a time series of position vectors generally obtained from GPS observations. Velocity vector is required for satellite gravimetry application. It cannot directly be observed and should be numerically determined from position vectors. Numerical differentiation is usually employed for a satellite’s velocity, and acceleration determination. However, noise amplification is the single obstacle to the numerical differentiation. As an alternative, velocity vector is considered as a part of the state vector and is determined using the Kalman filter method. In this study, velocity vector is computed using the numerical differentiation (e.g., 9-point Newton interpolation scheme) and Kalman filtering for the GRACE twin satellites. The numerical results show that Kalman filtering yields more accurate results than numerical differentiation when they are compared with the intersatellite range-rate measurements.

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Simonov, Konstantin V., Valentin B. Kashkin, Тatyana V. Rubleva, and Konstantin V. Krasnoshekov. "Analysis of GRACE satellite measurements over seismically active areas of the strongest earthquakes." E3S Web of Conferences 75 (2019): 02007. http://dx.doi.org/10.1051/e3sconf/20197502007.

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The study is devoted to the analysis of the features of the change in the parameter EWH (Equivalent Water Height) over the geoid from the satellite measurements of the GRACE space system in seismically active areas of the strongest underwater earthquakes. The GRACE satellite data archive was created. An interpretation of the disturbed state of the geomedium using digital maps of the spatial distribution of the parameter EWH is performed.

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Su, Xiaoli, Junyi Guo, C. K. Shum, Zhicai Luo, and Yu Zhang. "Increased Low Degree Spherical Harmonic Influences on Polar Ice Sheet Mass Change Derived from GRACE Mission." Remote Sensing 12, no. 24 (December 20, 2020): 4178. http://dx.doi.org/10.3390/rs12244178.

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Replacing estimates of C20 from the Gravity Recovery and Climate Experiment (GRACE) monthly gravity field solutions by those from satellite laser ranging (SLR) data and including degree one terms has become a standard procedure for proper science applications in the satellite gravimetry community. Here, we assess the impact of degree one terms, SLR-based C20 and C30 estimates on GRACE-derived polar ice sheet mass variations. We report that degree one terms recommended for GRACE Release 06 (RL06) data have an impact of 2.5 times more than those for GRACE RL05 data on the mass trend estimates over the Greenland and the Antarctic ice sheets. The latest recommended C20 solutions in GRACE Technical Note 14 (TN14) affect the mass trend estimates of ice sheets in absolute value by more than 50%, as compared to those in TN11 and TN07. The SLR-based C30 replacement has some impact on the Antarctic ice sheet mass variations, mainly depending on the length of the study period. This study emphasizes that reliable solutions of low degree spherical harmonics are crucial for accurately deriving ice sheet mass balance from satellite gravimetry.

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Gruber, Christian, Sergei Rudenko, Andreas Groh, Dimitrios Ampatzidis, and Elisa Fagiolini. "Earth's surface mass transport derived from GRACE, evaluated by GPS, ICESat, hydrological modeling and altimetry satellite orbits." Earth Surface Dynamics 6, no. 4 (December 7, 2018): 1203–18. http://dx.doi.org/10.5194/esurf-6-1203-2018.

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Abstract. The Gravity Recovery and Climate Experiment (GRACE) delivered the most accurate quantification of global mass variations with monthly temporal resolution on large spatial scales. Future gravity missions will take advantage of improved measurement technologies, such as enhanced orbit configurations and tracking systems, as well as reduced temporal aliasing errors. In order to achieve the latter, sub-monthly to daily innovative models are computed. In addition, non-conventional methods based on radial basis functions (RBFs) and mascons will give the ability to compute models in regional and global representations as well. We show that the RBF modeling technique can be used for processing GRACE data yielding global gravity field models which fit independent reference values at the same level as commonly accepted global geopotential models based on spherical harmonics. The present study compares for the first time a complete global series of solutions in order to quantify recent ice mass changes. We further compare the ice-induced crustal deformations due to the dynamic loading of the crustal layer with the Global Positioning System (GPS) uplift measurements along Greenland's coastline. Available mass change estimates based on Ice, Cloud, and land Elevation Satellite (ICESat) laser altimetry measurements both in Greenland and Antarctica are used to assess the GRACE results. A comparison of GRACE time series with hydrological modeling for various basin extensions reveals overall high correlation to surface and groundwater storage compartments. The forward computation of satellite orbits for altimetry satellites such as Envisat, Jason-1 and Jason-2 compares the performance of GRACE time-variable gravity fields with models including time variability, such as EIGEN-6S4.

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Yuan, Junjun, Shanshi Zhou, Xiaogong Hu, Long Yang, Jianfeng Cao, Kai Li, and Min Liao. "Impact of Attitude Model, Phase Wind-Up and Phase Center Variation on Precise Orbit and Clock Offset Determination of GRACE-FO and CentiSpace-1." Remote Sensing 13, no. 13 (July 5, 2021): 2636. http://dx.doi.org/10.3390/rs13132636.

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Currently, low Earth orbit (LEO) satellites are attracting great attention in the navigation enhancement field because of their stronger navigation signal and faster elevation variation than medium Earth orbit (MEO) satellites. To meet the need for real-time and precise positioning, navigation and timing (PNT) services, the first and most difficult task is correcting errors in the process of precise LEO orbit and clock offset determination as much as possible. Launched in 29 September 2018, the CentiSpace-1 (CS01) satellite is the first experimental satellite of LEO-based navigation enhancement system constellations developed by Beijing Future Navigation Technology Co. Ltd. To analyze the impact of the attitude model, carrier phase wind-up (PWU) and phase center variation (PCV) on precise LEO orbit and clock offset in an LEO-based navigation system that needs extremely high precision, we not only select the CS01 satellite as a testing spacecraft, but also the Gravity Recovery and Climate Experiment Follow-On (GRACE-FO). First, the dual-frequency global positioning system (GPS) data are collected and the data quality is assessed by analyzing the performance of tracking GPS satellites, multipath errors and signal to noise ratio (SNR) variation. The analysis results show that the data quality of GRACE-FO is slightly better than CS01. With residual analysis and overlapping comparison, a further orbit quality improvement is possible when we further correct the errors of the attitude model, PWU and PCV in this paper. The final three-dimensional (3D) root mean square (RMS) of the overlapping orbit for GRACE-FO and CS01 is 2.08 cm and 1.72 cm, respectively. Meanwhile, errors of the attitude model, PWU and PCV can be absorbed partly in the clock offset and these errors can generate one nonnegligible effect, which can reach 0.02~0.05 ns. The experiment results indicate that processing the errors of the attitude model, PWU and PCV carefully can improve the consistency of precise LEO orbit and clock offset and raise the performance of an LEO-based navigation enhancement system.

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Śliwińska, Justyna, and Jolanta Nastula. "Determining and Evaluating the Hydrological Signal in Polar Motion Excitation from Gravity Field Models Obtained from Kinematic Orbits of LEO Satellites." Remote Sensing 11, no. 15 (July 30, 2019): 1784. http://dx.doi.org/10.3390/rs11151784.

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This study evaluates the gravity field solutions based on high-low satellite-to-satellite tracking (hl-SST) of low-Earth-orbit (LEO) satellites: GRACE, Swarm, TerraSAR-X, TanDEM-X, MetOp-A, MetOp-B, and Jason 2, by converting them into hydrological polar motion excitation functions (or hydrological angular momentum (HAM)). The resulting HAM series are compared with the residuals of observed polar motion excitation (geodetic residuals, GAO) derived from precise geodetic measurements, and the HAM obtained from the GRACE ITSG 2018 solution. The findings indicate a large impact of orbital altitude and inclination on the accuracy of derived HAM. The HAM series obtained from Swarm data are found to be the most consistent with GAO. Visible differences are found in HAM obtained from GRACE and Swarm orbits and provided by different processing centres. The main reasons for such differences are likely to be different processing approaches and background models. The findings of this study provide important information on alternative data sets that may be used to provide continuous polar motion excitation observations, of which the Swarm solution provided by the Astronomical Institute, Czech Academy of Sciences, is the most accurate. However, further analysis is needed to determine which processing algorithms are most appropriate to obtain the best correspondence with GAO.

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Sun, Alexander, Bridget Scanlon, Amir AghaKouchak, and Zizhan Zhang. "Using GRACE Satellite Gravimetry for Assessing Large-Scale Hydrologic Extremes." Remote Sensing 9, no. 12 (December 11, 2017): 1287. http://dx.doi.org/10.3390/rs9121287.

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Kuo, Chung-Yen, C. K. Shum, Jun-yi Guo, Yuchan Yi, Alexander Braun, Ichiro Fukumori, Koji Matsumoto, Tadahiro Sato, and Kazuo Shibuya. "Southern Ocean mass variation studies using GRACE and satellite altimetry." Earth, Planets and Space 60, no. 5 (May 2008): 477–85. http://dx.doi.org/10.1186/bf03352814.

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Junyan, Yang, Xin Zhou, Shuang Yi, and Wenke Sun. "Determining dislocation love numbers using GRACE satellite mission gravity data." Geophysical Journal International 203, no. 1 (August 20, 2015): 257–69. http://dx.doi.org/10.1093/gji/ggv265.

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Ramillien, G., A. Cazenave, and O. Brunau. "Global time variations of hydrological signals from GRACE satellite gravimetry." Geophysical Journal International 158, no. 3 (July 27, 2004): 813–26. http://dx.doi.org/10.1111/j.1365-246x.2004.02328.x.

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Sadeghi, Morteza, Lun Gao, Ardeshir Ebtehaj, Jean-Pierre Wigneron, Wade T. Crow, John T. Reager, and Arthur W. Warrick. "Retrieving global surface soil moisture from GRACE satellite gravity data." Journal of Hydrology 584 (May 2020): 124717. http://dx.doi.org/10.1016/j.jhydrol.2020.124717.

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Golmohamadi, Mehdi, and Gholamreza Joodaki. "Statistical downscaling of GRACE gravity satellite-derived groundwater level data." Journal of Geospatial Information Technology 8, no. 3 (January 1, 2021): 83–101. http://dx.doi.org/10.52547/jgit.8.3.83.

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Salam, Muhammad, Muhammad Jehanzeb Masud Cheema, Wanchang Zhang, Saddam Hussain, Azeem Khan, Muhammad Bilal, Arfan Arshad, Sikandar Ali, and Muhammad Awais Zaman. "GROUNDWATER STORAGE CHANGE ESTIMATION USING GRACE SATELLITE DATA IN INDUS BASIN." Big Data In Water Resources Engineering (BDWRE) 1, no. 1 (February 4, 2020): 10–15. http://dx.doi.org/10.26480/bdwre.01.2020.10.15.

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Over exploitation of Ground Water (GW) has resulted in lowering of water table in the Indus Basin. While waterlogging, salinity and seawater intrusion has resulted in rising of water table in Indus Basin. The sparse piezometer network cannot provide sufficient data to map groundwater changes spatially. To estimate groundwater change in this region, data from Gravity Recovery and Climate Experiment (GRACE) satellite was used. GRACE measures (Total Water Storage) TWS and used to estimate groundwater storage change. Net change in storage of groundwater was estimated from the change in TWS by including the additional components such as Soil Moisture (SM), Surface water storage (Qs) and snowpack equivalent water (SWE). For the estimation of these components Global Land Data Assimilation system (GLDAS) Land Surface Models (LSMs) was used. Both GRACE and GLDAS produce results for the Indus Basin for the period of April 2010 to January 2017. The monitoring well water-level records from the Scarp Monitoring Organization (SMO) and the Punjab Irrigation and Drainage Authority (PIDA) from April 2009 to December 2016 were used. The groundwater results from different combinations of GRACE products GFZ (GeoforschungsZentrum Potsdam) CSR (Center for Space Research at University of Texas, Austin) JPL (Jet Propulsion Laboratory) and GLDAS LSMs (CLM, NOAH and VIC) are calibrated (April 2009-2014) and validated (April 2015-April 2016) with in-situ measurements. For yearly scale, their correlation coefficient reaches 0.71 with Nash-Sutcliffe Efficiency (NSE) 0.82. It was estimated that net loss in groundwater storage is at mean rate of 85.01 mm per year and 118,668.16 Km3 in the 7 year of study period (April 2010-Jan 2017). GRACE TWS data were also able to pick up the signals from the large-scale flooding events observed in 2010 and 2014. These flooding events played a significant role in the replenishment of the groundwater system in the Indus Basin. Our study indicates that the GRACE based estimation of groundwater storage changes is skillful enough to provide monthly updates on the trend of the groundwater storage changes for resource managers and policy makers of Indus Basin.

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Sasgen, Ingo, Hannes Konrad, Veit Helm, and Klaus Grosfeld. "High-Resolution Mass Trends of the Antarctic Ice Sheet through a Spectral Combination of Satellite Gravimetry and Radar Altimetry Observations." Remote Sensing 11, no. 2 (January 14, 2019): 144. http://dx.doi.org/10.3390/rs11020144.

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Time-variable gravity measurements from the Gravity Recovery and Climate Experiment (GRACE) and GRACE-Follow On (GRACE-FO) missions and satellite altimetry measurements from CryoSat-2 enable independent mass balance estimates of the Earth’s glaciers and ice sheets. Both approaches vary in terms of their retrieval principles and signal-to-noise characteristics. GRACE/GRACE-FO recovers the gravity disturbance caused by changes in the mass of the entire ice sheet with a spatial resolution of 300 to 400 km. In contrast, CryoSat-2measures travel times of a radar signal reflected close to the ice sheet surface, allowing changes of the surface topography to be determined with about 5 km spatial resolution. Here, we present a method to combine observations from the both sensors, taking into account the different signal and noise characteristics of each satellite observation that are dependent on the spatial wavelength. We include uncertainties introduced by the processing and corrections, such as the choice of the re-tracking algorithm and the snow/ice volume density model for CryoSat-2, or the filtering of correlated errors and the correction for glacial-isostatic adjustment (GIA) for GRACE. We apply our method to the Antarctic ice sheet and the time period 2011–2017, in which GRACE and CryoSat-2 were simultaneously operational, obtaining a total ice mass loss of 178 ± 23 Gt yr−1. We present a map of the rate of mass change with a spatial resolution of 40 km that is evaluable across all spatial scales, and more precise than estimates based on a single satellite mission.

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Zhao, Meng, Geruo A, Isabella Velicogna, and John S. Kimball. "A Global Gridded Dataset of GRACE Drought Severity Index for 2002–14: Comparison with PDSI and SPEI and a Case Study of the Australia Millennium Drought." Journal of Hydrometeorology 18, no. 8 (July 18, 2017): 2117–29. http://dx.doi.org/10.1175/jhm-d-16-0182.1.

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Abstract A new monthly global drought severity index (DSI) dataset developed from satellite-observed time-variable terrestrial water storage changes from the Gravity Recovery and Climate Experiment (GRACE) is presented. The GRACE-DSI record spans from 2002 to 2014 and will be extended with the ongoing GRACE and scheduled GRACE Follow-On missions. The GRACE-DSI captures major global drought events during the past decade and shows overall favorable spatiotemporal agreement with other commonly used drought metrics, including the Palmer drought severity index (PDSI) and the standardized precipitation evapotranspiration index (SPEI). The assets of the GRACE-DSI are 1) that it is based solely on satellite gravimetric observations and thus provides globally consistent drought monitoring, particularly where sparse ground observations (especially precipitation) constrain the use of traditional model-based monitoring methods; 2) that it has a large footprint (~350 km), so it is suitable for assessing regional- and global-scale drought; and 3) that it is sensitive to the overall terrestrial water storage component of the hydrologic cycle and therefore complements existing drought monitoring datasets by providing information about groundwater storage changes, which affect soil moisture recharge and drought recovery. In Australia, it is demonstrated that combining GRACE-DSI with other satellite environmental datasets improves the characterization of the 2000s “Millennium Drought” at shallow surface and subsurface soil layers. Contrasting vegetation greenness response to surface and underground water supply changes between western and eastern Australia is found, which might indicate that these regions have different relative plant rooting depths.

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Jin, Shuanggen, Guiping Feng, and Ole Andersen. "Errors of Mean Dynamic Topography and Geostrophic Current Estimates in China’s Marginal Seas from GOCE and Satellite Altimetry." Journal of Atmospheric and Oceanic Technology 31, no. 11 (November 2014): 2544–55. http://dx.doi.org/10.1175/jtech-d-13-00243.1.

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AbstractThe Gravity Field and Steady-State Ocean Circulation Explorer (GOCE) and satellite altimetry can provide very detailed and accurate estimates of the mean dynamic topography (MDT) and geostrophic currents in China’s marginal seas, such as, the newest high-resolution GOCE gravity field model GO-CONS-GCF-2-TIM-R4 and the new Centre National d’Etudes Spatiales mean sea surface model MSS_CNES_CLS_11 from satellite altimetry. However, errors and uncertainties of MDT and geostrophic current estimates from satellite observations are not generally quantified. In this paper, errors and uncertainties of MDT and geostrophic current estimates from satellite gravimetry and altimetry are investigated and evaluated in China’s marginal seas. The cumulative error in MDT from GOCE is reduced from 22.75 to 9.89 cm when compared to the Gravity Recovery and Climate Experiment (GRACE) gravity field model ITG-Grace2010 results in the region. The errors of the geostrophic currents from GRACE are smaller than from GOCE with the truncation degrees 90 and 120. However, when the truncation degree is higher than 150, the GRACE mean errors increase rapidly and become significantly larger than the GOCE results. The geostrophic velocities based on GOCE-TIM4 have higher accuracy and spatial resolution, and the mean error is about 12.6 cm s−1, which is more consistent with the in situ drifter’s results than using GRACE data.

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Fok, Hok, and Qing He. "Water Level Reconstruction Based on Satellite Gravimetry in the Yangtze River Basin." ISPRS International Journal of Geo-Information 7, no. 7 (July 23, 2018): 286. http://dx.doi.org/10.3390/ijgi7070286.

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The monitoring of hydrological extremes requires water level measurement. Owing to the decreasing number of continuous operating hydrological stations globally, remote sensing indices have been advocated for water level reconstruction recently. Nevertheless, the feasibility of gravimetrically derived terrestrial water storage (TWS) and its corresponding index for water level reconstruction have not been investigated. This paper aims to construct a correlative relationship between observed water level and basin-averaged Gravity Recovery and Climate Experiment (GRACE) TWS and its Drought Severity Index (GRACE-DSI), for the Yangtze river basin on a monthly temporal scale. The results are subsequently compared against traditional remote sensing, Palmer’s Drought Severity Index (PDSI), and El Niño Southern Oscillation (ENSO) indices. Comparison of the water level reconstructed from GRACE TWS and its index, and that of remote sensing against observed water level reveals a Pearson Correlation Coefficient (PCC) above 0.90 and below 0.84, with a Root-Mean-Squares Error (RMSE) of 0.88–1.46 m, and 1.41–1.88 m and a Nash-Sutcliffe model efficiency coefficient (NSE) above 0.81 and below 0.70, respectively. The ENSO-reconstructed water levels are comparable to those based on remote sensing, whereas the PDSI-reconstructed water level shows a similar performance to that of GRACE TWS. The water level predicted at the location of another station also exhibits a similar performance. It is anticipated that the basin-averaged, remotely-sensed hydrological variables and their standardized forms (e.g., GRACE TWS and GRACE-DSI) are viable alternatives for reconstructing water levels for large river basins affected by the hydrological extremes under ENSO influence.

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MAEDA, Hidetoshi, Hyungjun KIM, and Yukiko HIRABAYASHI. "Estimation of glacier mass changes using GRACE satellite and numerical models." Journal of Japan Society of Civil Engineers, Ser. G (Environmental Research) 69, no. 5 (2013): I_53—I_59. http://dx.doi.org/10.2208/jscejer.69.i_53.

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Zheng, Wei, and Houze Xu. "Progress in satellite gravity recovery from implemented CHAMP, GRACE and GOCE and future GRACE Follow-On missions." Geodesy and Geodynamics 6, no. 4 (July 2015): 241–47. http://dx.doi.org/10.1016/j.geog.2015.05.005.

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Darbeheshti, Neda, Florian Wöske, Matthias Weigelt, Christopher Mccullough, and Hu Wu. "GRACETOOLS—GRACE Gravity Field Recovery Tools." Geosciences 8, no. 9 (September 15, 2018): 350. http://dx.doi.org/10.3390/geosciences8090350.

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This paper introduces GRACETOOLS, the first open source gravity field recovery tool using GRACE type satellite observations. Our aim is to initiate an open source GRACE data analysis platform, where the existing algorithms and codes for working with GRACE data are shared and improved. We describe the first release of GRACETOOLS that includes solving variational equations for gravity field recovery using GRACE range rate observations. All mathematical models are presented in a matrix format, with emphasis on state transition matrix, followed by details of the batch least squares algorithm. At the end, we demonstrate how GRACETOOLS works with simulated GRACE type observations. The first release of GRACETOOLS consist of all MATLAB M-files and is publicly available at Supplementary Materials.

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Ray, R. D., B. D. Loomis, S. B. Luthcke, and K. E. Rachlin. "Tests of ocean-tide models by analysis of satellite-to-satellite range measurements: an update." Geophysical Journal International 217, no. 2 (February 1, 2019): 1174–78. http://dx.doi.org/10.1093/gji/ggz062.

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SUMMARY Seven years of GRACE intersatellite range-rate measurements are used to test the new ocean tide model FES2014 and to compare against similar results obtained with earlier models. These qualitative assessments show that FES2014 represents a marked improvement in accuracy over its earlier incarnation, FES2012, with especially notable improvements in the Arctic Ocean for constituents K1 and S2. Degradation appears to have occurred in two anomalous regions: the Ross Sea for the O1 constituent and the Weddell Sea for M2.

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Journal articles on the topic 'GRACE Satellite'

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