scholarly journals Estimation of regional mass anomalies from Gravity Recovery and Climate Experiment (GRACE) over Himalayan region

2014 ◽  
Vol XL-8 ◽  
pp. 329-332 ◽  
Author(s):  
R. Agrawal ◽  
S. K. Singh ◽  
A. S. Rajawat ◽  
Ajai
Keyword(s):  
Gravity Field ◽  
Spherical Harmonic ◽  
Regional Scale ◽  
Indus Basin ◽  
Time Variability ◽  
Annual Change ◽  
Large Area ◽  
Satellite Mission ◽  
Grace Data ◽  
Gravity Recovery

Time-variable gravity changes are caused by a combination of postglacial rebound, redistribution of water and snow/ice on land and as well as in the ocean. The Gravity Recovery and Climate Experiment (GRACE) satellite mission, launched in 2002, provides monthly average of the spherical harmonic co-efficient. These spherical harmonic co-efficient describe earth’s gravity field with a resolution of few hundred kilometers. Time-variability of gravity field represents the change in mass over regional level with accuracies in cm in terms of Water Equivalent Height (WEH). The WEH reflects the changes in the integrated vertically store water including snow cover, surface water, ground water and soil moisture at regional scale. GRACE data are also sensitive towards interior strain variation, surface uplift and surface subsidence cover over a large area. <br><br> GRACE data was extracted over the three major Indian River basins, Indus, Ganga and Brahmaputra, in the Himalayas which are perennial source of fresh water throughout the year in Northern Indian Plain. Time series analysis of the GRACE data was carried out from 2003&ndash;2012 over the study area. Trends and amplitudes of the regional mass anomalies in the region were estimated using level 3 GRACE data product with a spatial resolution at 10 by 10 grid provided by Center for Space Research (CSR), University of Texas at Austin. Indus basin has shown a subtle decreasing trend from 2003&ndash;2012 however it was observed to be statistically insignificant at 95 % confidence level. Ganga and Brahmaputra basins have shown a clear decreasing trend in WEH which was also observed to be statistically significant. The trend analysis over Ganga and Brahamputra basins have shown an average annual change of &minus;1.28 cm and &minus;1.06 cm in terms of WEH whereas Indus basin has shown a slight annual change of &minus;0.07 cm. This analysis will be helpful to understand the loss of mass in terms of WEH over Indian Himalayas and will be crucial for hydrological and climate applications at regional scale.

V04 Level-1 data processing status for GRACE and GRACE Follow-On

2020 ◽  
Author(s):  
Tamara Bandikova ◽  
Hui Ying Wen ◽  
Meegyeong Paik ◽  
William Bertiger ◽  
Mark Miller ◽  
...  
Keyword(s):  
Data Processing ◽  
Gravity Field ◽  
Attitude Determination ◽  
Precise Orbit Determination ◽  
Sensor Data ◽  
Satellite Mission ◽  
Gravity Field Recovery ◽  
Grace Data ◽  
Level 1 ◽  
Gravity Recovery

&lt;p&gt;On May 22, 2020, the Gravity Recovery and Climate Experiment Follow-On (GRACE-FO), will celebrate two years of successful in-orbit operation. The primary goal of this satellite mission is to provide information about time variations of the Earth&amp;#8217;s gravity field. This is possible due to precise orbit determination and inter-satellite ranging by determining the relative clock alignment of the USOs, precise attitude determination and accelerometry. High quality satellite observations are one of the fundamental requirements for successful gravity field recovery. NASA/Caltech Jet Propulsion Laboratory is the official Level-1 data processing and analysis center. The GRACE-FO Level-1 data are currently being processed with software version V04. This software will be used also for final reprocessing of the GRACE (2002-2017) Level-1 data. Here we present the analysis of two years of GRACE-FO sensor data as well as a preview of the reprocessed GRACE data, and discuss the measurement performance.&lt;/p&gt;

scholarly journals Joint analysis of selected GRACE monthly spherical harmonic solutions and monthly MASCON solutions

2021 ◽  
Vol 51 (1) ◽  
pp. 47-61
Author(s):  
Adam NOVÁK ◽  
Juraj JANÁK ◽  
Barbora KOREKÁČOVÁ
Keyword(s):  
Gravity Field ◽  
Spherical Harmonic ◽  
Statistical Significance ◽  
Detailed Comparison ◽  
Joint Analysis ◽  
Satellite Mission ◽  
Science Data ◽  
Gravity Field Model ◽  
Global Gravity ◽  
Gravity Field Models

Study presented in this paper is focused on comparison and statistical assessment of differences between the selected Level 2 products of the satellite mission Gravity Recovery and Climate Experiment (GRACE). Global monthly gravity field models in terms of spherical harmonic coefficients produced by three institutes of GRACE Science Data System are compared with the partially independent MASCON global gravity field model. Detailed comparison and statistical analysis of differences is performed in 5 selected river basins: Amazon, Congo, Danube, Yenisei and Lena. For each spherical harmonic solution, 8 different filtrations available at International Center for Global Gravity Field Models (ICGEM) are tested over the time span from April 2002 to July 2016. Fischer test at two significance levels 10% and 5% has been performed in order to qualify the statistical significance between the particular solutions.

MATLAB tools for the post-processing of GRACE temporal gravity field solutions

2020 ◽  
Author(s):  
Dimitrios Piretzidis ◽  
Michael Sideris
Keyword(s):  
Gravity Field ◽  
Land Surface ◽  
Optimal Strategies ◽  
Post Processing ◽  
Satellite Mission ◽  
Surface Mass ◽  
Isostatic Adjustment ◽  
Processing Strategies ◽  
Grace Data ◽  
Temporal Gravity

&lt;p&gt;We present a collection of MATLAB tools for the post-processing of temporal gravity field solutions from the Gravity Recovery and Climate Experiment (GRACE) satellite mission. GRACE final products are in the form of monthly sets of spherical harmonic coefficients and have been extensively used by the scientific community to study the land surface mass redistribution that is predominantly due to ice melting, glacial isostatic adjustment, seismic activity and hydrological phenomena. Since the launch of GRACE satellites, a substantial effort has been made to develop processing strategies and improve the surface mass change estimates.&lt;/p&gt;&lt;p&gt;The MATAB software presented in this work is developed and used by the Gravity and Earth Observation group at the department of Geomatics Engineering, University of Calgary. A variety of techniques and tools for the processing of GRACE data are implemented, tested and analyzed. Some of the software capabilities are: filtering of GRACE data using decorrelation and smoothing techniques, conversion of gravity changes into mass changes on the Earth&amp;#8217;s spherical, ellipsoidal and topographical surface, implementation of forward modeling techniques for the estimation and removal of long-term trends due to ice mass melting, basin-specific spatial averaging in the spatial and spectral domain, time series smoothing and decomposition techniques, and data visualization.&lt;/p&gt;&lt;p&gt;All tools use different levels of parameterization in order to assist both expert users and non-specialists. Such a software makes the comparison between different GRACE processing methods and parameters used easier, leading to optimal strategies for the estimation of surface mass changes and to the standardization of GRACE data post-processing. It could also facilitate the use of GRACE data to non-geodesists.&lt;/p&gt;

scholarly journals Reduced misclosure of global sea-level budget with updated Tongji-Grace2018 solution

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Fengwei Wang ◽  
Yunzhong Shen ◽  
Qiujie Chen ◽  
Yu Sun
Keyword(s):  
Sea Level ◽  
Spherical Harmonic ◽  
Mass Change ◽  
Global Ocean ◽  
Argo Data ◽  
Ocean Mass ◽  
Grace Data ◽  
Budget Equation ◽  
Global Sea Level ◽  
Gravity Recovery

AbstractThe global sea-level budget is studied using the Gravity Recovery and Climate Experiment (GRACE) solutions, Satellite Altimetry and Argo observations based on the updated budget equation. When the global ocean mass change is estimated with the updated Tongji-Grace2018 solution, the misclosure of the global sea-level budget can be reduced by 0.11–0.22 mm/year compared to four other recent solutions (i.e. CSR RL06, GFZ RL06, JPL RL06 and ITSG-Grace2018) over the period January 2005 to December 2016. When the same missing months as the GRACE solution are deleted from altimetry and Argo data, the misclosure will be reduced by 0.06 mm/year. Once retained the GRACE C20 term, the linear trends of Tongji-Grace2018 and ITSG-Grace2018 solutions are 2.60 ± 0.16 and 2.54 ± 0.16 mm/year, closer to 2.60 ± 0.14 mm/year from Altimetry–Argo than the three RL06 official solutions. Therefore, the Tongji-Grace2018 solution can reduce the misclosure between altimetry, Argo and GRACE data, regardless of whether the C20 term is replaced or not, since the low-degree spherical harmonic coefficients of the Tongji-Grace2018 solution can capture more ocean signals, which are confirmed by the statistical results of the time series of global mean ocean mass change derived from five GRACE solutions with the spherical harmonic coefficients truncated to different degrees and orders.

Dynamics of Terrestrial Water Storage Change from Satellite and Surface Observations and Modeling

2010 ◽  
Vol 11 (1) ◽  
pp. 156-170 ◽  
Author(s):  
Qiuhong Tang ◽  
Huilin Gao ◽  
Pat Yeh ◽  
Taikan Oki ◽  
Fengge Su ◽  
...  
Keyword(s):  
Water Cycle ◽  
Regional Scale ◽  
Water Storage ◽  
Terrestrial Water Storage ◽  
Surface Observation ◽  
Grace Data ◽  
Terrestrial Water ◽  
Gravity Recovery ◽  
Storage Change ◽  
Surface Observations

Abstract Terrestrial water storage (TWS) is a fundamental component of the water cycle. On a regional scale, measurements of terrestrial water storage change (TWSC) are extremely scarce at any time scale. This study investigates the feasibility of estimating monthly-to-seasonal variations of regional TWSC from modeling and a combination of satellite and in situ surface observations based on water balance computations that use ground-based precipitation observations in both cases. The study area is the Klamath and Sacramento River drainage basins in the western United States (total area of about 110 000 km2). The TWSC from the satellite/surface observation–based estimates is compared with model results and land water storage from the Gravity Recovery and Climate Experiment (GRACE) data. The results show that long-term evapotranspiration estimates and runoff measurements generally balance with observed precipitation, suggesting that the evapotranspiration estimates have relatively small bias for long averaging times. Observations show that storage change in water management reservoirs is about 12% of the seasonal amplitude of the TWSC cycle, but it can be up to 30% at the subbasin scale. Comparing with predevelopment conditions, the satellite/surface observation–based estimates show larger evapotranspiration and smaller runoff than do modeling estimates, suggesting extensive anthropogenic alteration of TWSC in the study area. Comparison of satellite/surface observation–based and GRACE TWSC shows that the seasonal cycle of terrestrial water storage is substantially underestimated by GRACE.

scholarly journals Downscaling GRACE total water storage change using partial least squares regression

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Bramha Dutt Vishwakarma ◽  
Jinwei Zhang ◽  
Nico Sneeuw
Keyword(s):  
Water Mass ◽  
Spatial Scales ◽  
Water Storage ◽  
Temporal Variations ◽  
Least Squares Regression ◽  
Total Water ◽  
Satellite Mission ◽  
Grace Data ◽  
Gravity Recovery ◽  
Storage Change

AbstractThe Gravity Recovery And Climate Experiment (GRACE) satellite mission recorded temporal variations in the Earth’s gravity field, which are then converted to Total Water Storage Change (TWSC) fields representing an anomaly in the water mass stored in all three physical states, on and below the surface of the Earth. GRACE provided a first global observational record of water mass redistribution at spatial scales greater than 63000 km2. This limits their usability in regional hydrological applications. In this study, we implement a statistical downscaling approach that assimilates 0.5° × 0.5° water storage fields from the WaterGAP hydrology model (WGHM), precipitation fields from 3 models, evapotranspiration and runoff from 2 models, with GRACE data to obtain TWSC at a 0.5° × 0.5° grid. The downscaled product exploits dominant common statistical modes between all the hydrological datasets to improve the spatial resolution of GRACE. We also provide open access to scripts that researchers can use to produce downscaled TWSC fields with input observations and models of their own choice.

scholarly journals GRACE application for geological and geographical problems

2017 ◽  
pp. 3-7
Author(s):  
N. S. Tkachenko ◽  
I. V. Lygin
Keyword(s):  
High Resolution ◽  
Literature Review ◽  
Gravity Field ◽  
Satellite Mission ◽  
Earth’S Gravity Field ◽  
Precise Mapping ◽  
Grace Satellite ◽  
Gravity Recovery

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.

scholarly journals Instrument Data Simulations for GRACE Follow-on: Observation and Noise Models

2017 ◽  
Author(s):  
Neda Darbeheshti ◽  
Henry Wegener ◽  
Vitali Müller ◽  
Majid Naeimi ◽  
Gerhard Heinzel ◽  
...  
Keyword(s):  
Gravity Field ◽  
Simulated Data ◽  
Laser Interferometry ◽  
Scientific Basis ◽  
Satellite Mission ◽  
Earth’S Gravity Field ◽  
Gravity Field Recovery ◽  
Grace Data ◽  
Data Files ◽  
Grace Mission

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 fifteen years now. The GRACE twin satellites use microwave ranging with micrometer precision to measure 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 nanometer 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.

scholarly journals Instrument data simulations for GRACE Follow-on: observation and noise models

2017 ◽  
Vol 9 (2) ◽  
pp. 833-848 ◽  
Author(s):  
Neda Darbeheshti ◽  
Henry Wegener ◽  
Vitali Müller ◽  
Majid Naeimi ◽  
Gerhard Heinzel ◽  
...  
Keyword(s):  
Gravity Field ◽  
Simulated Data ◽  
Laser Interferometry ◽  
Scientific Basis ◽  
Satellite Mission ◽  
Earth’S Gravity Field ◽  
Gravity Field Recovery ◽  
Grace Data ◽  
Data Files ◽  
Grace Mission

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.

scholarly journals Spatio-Temporal Patterns of Mass Changes in Himalayan Glaciated Region from EOF Analyses of GRACE Data

2021 ◽  
Vol 13 (2) ◽  
pp. 265
Author(s):  
Harika Munagapati ◽  
Virendra M. Tiwari
Keyword(s):  
Temperature Anomaly ◽  
Mass Gain ◽  
Snow Accumulation ◽  
Empirical Orthogonal Functions ◽  
Total Water ◽  
Orthogonal Functions ◽  
Grace Data ◽  
Grace Satellite ◽  
Spatio Temporal ◽  
Gravity Recovery

The nature of hydrological seasonality over the Himalayan Glaciated Region (HGR) is complex due to varied precipitation patterns. The present study attempts to exemplify the spatio-temporal variation of hydrological mass over the HGR using time-variable gravity from the Gravity Recovery and Climate Experiment (GRACE) satellite for the period of 2002–2016 on seasonal and interannual timescales. The mass signal derived from GRACE data is decomposed using empirical orthogonal functions (EOFs), allowing us to identify the three broad divisions of HGR, i.e., western, central, and eastern, based on the seasonal mass gain or loss that corresponds to prevailing climatic changes. Further, causative relationships between climatic variables and the EOF decomposed signals are explored using the Granger causality algorithm. It appears that a causal relationship exists between total precipitation and total water storage from GRACE. EOF modes also indicate certain regional anomalies such as the Karakoram mass gain, which represents ongoing snow accumulation. Our causality result suggests that the excessive snowfall in 2005–2008 has initiated this mass gain. However, as our results indicate, despite the dampening of snowfall rates after 2008, mass has been steadily increasing in the Karakorum, which is attributed to the flattening of the temperature anomaly curve and subsequent lower melting after 2008.

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