- document
-
Han, Shin-Chan (author), Sauber, Jeanne (author), Broerse, D.B.T. (author), Pollitz, Fred (author), Okal, Emile (author), Jeon, Taehwan (author), Seo, Ki Weon (author), Stanaway, Richard (author)Earthquakes involve mass redistribution within the solid Earth and the ocean, and as a result, perturb the Earth's gravitational field. For most of the shallow (<60 km) earthquakes with M<sub>w</sub> > 8.0, the GRACE satellite gravity measurements suggest considerable volumetric disturbance of rocks. At a spatial scale of hundreds of km...journal article 2024
- document
-
Sabzehee, F. (author), Amiri Simkooei, A. (author), Iran Pour, S. (author), Vishwakarma, B.D. (author), Kerachian, R. (author)The Urmia lake in north-west Iran has dried up to perilously low levels in the past two decades. In this study, we investigate the drivers behind the decline in lake water level with the help of in-situ and remote sensing data. We use total water storage (TWS) changes from the gravity recovery and climate experiment (GRACE) satellite mission....journal article 2023
- document
-
Dayside Upper-Thermospheric Density Fluctuations as Observed by GRACE and GRACE-FO at ∼500 km HeightPark, Jaeheung (author), van den IJssel, J.A.A. (author), Siemes, C. (author)We statistically investigate fluctuation amplitudes (normalized to the background values) of dayside low-/mid-latitude upper-thermospheric mass density as observed by the Gravity Recovery and Climate Experiment (GRACE) and GRACE-Follow-On (GRACE-FO) spacecraft at ∼500 km altitude between 2002 and 2022. There are three new findings in our...journal article 2023
- document
-
Chang, Guobin (author), Qian, N. (author), Bian, Shaofeng (author)Point-mass inversion is widely employed in GRACE level-2 data processing. Conventionally, the spherical harmonic (SH) coefficients are used indirectly: a set of pseudo measurements is generated first using the SH coefficients through SH synthesis; then the point-mass inversion is done with these pseudo measurements. To be statistically optimal,...journal article 2023
- document
-
Qian, N. (author), Chang, Guobin (author), Ditmar, P.G. (author), Gao, Jingxiang (author), Wei, Zhengqiang (author)High-frequency and correlated noise filtering is one of the important preprocessing steps for GRACE level-2 products before calculating mass anomaly. Decorrelation and denoising kernel (DDK) filters are usually considered as such optimal filters to solve this problem. In this work, a sparse DDK filter is proposed. This is achieved by...journal article 2022
- document
-
Qian, N. (author), Chang, Guobin (author), Gao, Jingxiang (author), Shen, Wenbin (author), Yan, Z. (author)Filtering for GRACE temporal gravity fields is a necessary step before calculating surface mass anomalies. In this study, we propose a new denoising and decorrelation kernel (DDK) filtering scheme called adaptive DDK filter. The involved error covariance matrix (ECM) adopts nothing but the monthly time‐variable released by several data...journal article 2022
- document
-
Ditmar, P.G. (author)A novel technique has been developed to assess noise levels in GRACE-based mass anomaly time-series when the true signal is not known. The technique is based on computing an optimal combination of analyzed time-series in the presence of a regularization. To find the optimal weights associated with individual time-series, variance component...journal article 2022
- document
-
Abedini, Abbas (author), Keller, Wolfgang (author), Amiri Simkooei, A. (author)Mass concentration (mascon) solutions for GRACE (Gravity Recovery and Climate Experiment) data are widely used in various regional-to-global mass change studies. The current advances in the mascon solution have mainly concentrated on improving the spatial resolution of the solution, enhancing the applied least-squares regularization, and the...journal article 2021
- document
-
Willen, M.O. (author), Broerse, D.B.T. (author), Groh, A. (author), Wouters, B. (author), Kuipers Munneke, P. (author), Horwath, M. (author), van den Broeke, M.R. (author), Schröder, L. (author)Satellite gravimetry and altimetry measurements record gravity and elevation changes, respectively, which are useful for determining mass and volume change of the Antarctic Ice Sheet. Common methods employ products from regional climate modeling and firn modeling to aid interpretation and to link volume changes to mass changes. Estimating...journal article 2021
- document
-
Ran, Jiangjun (author), Ditmar, P.G. (author), Liu, Lin (author), Xiao, Yun (author), Klees, R. (author), Tang, Xueyuan (author)Mascon products derived from Gravity Recovery and Climate Experiment satellite gravimetry data are widely used to study the Greenland ice sheet mass balance. However, the products released by different research groups—JPL, CSR, and GSFC—show noticeable discrepancies. To understand them, we compare those mascon products with mascon solutions...journal article 2021
- document
-
Hulsman, P. (author), Hrachowitz, M. (author), Savenije, Hubert (author)In the Luangwa basin in Zambia, long-term total water storage variations were observed with Gravity Recovery and Climate Experiment, but not reproduced by a standard conceptual hydrological model that encapsulates our current understanding of the dominant regional hydrological processes. The objective of this study was to identify potential...journal article 2021
- document
-
Vishwakarma, B.D. (author), Royston, S. (author), Riva, R.E.M. (author), Westaway, R.M. (author), Bamber, J.L. (author)The conventional sea level budget (SLB) equates changes in sea surface height with the sum of ocean mass and steric change, where solid-Earth movements are included as corrections but limited to the impact of glacial isostatic adjustment. However, changes in ocean mass load also deform the ocean bottom elastically. Until the early 2000s,...journal article 2020
- document
-
Guo, Xiang (author), Ditmar, P.G. (author), Zhao, Qile (author), Xiao, Yun (author)To monitor temporal variations of the Earth’s gravity field and mass transport in the Earth’s system, data from gravity recovery and climate experiment (GRACE) satellite mission and its successor GRACE Follow-On (GFO) are used. To fill in the temporal gap between these missions, other satellites’ kinematic orbits derived from GPS-based high...journal article 2020
- document
-
Tangdamrongsub, Natthachet (author), Han, Shin Chan (author), Yeo, In Young (author), Dong, Jianzhi (author), Steele-Dunne, S.C. (author), Willgoose, Garry (author), Walker, Jeffrey P. (author)Assimilating remote sensing observations into land surface models has become common practice to improve the accuracy of terrestrial water storage (TWS) estimates such as soil moisture and groundwater, for understanding the land surface interaction with the climate system, as well as assessing regional and global water resources. Such remote...journal article 2020
- document
-
Sun, Y. (author), Riva, R.E.M. (author), Ditmar, P.G. (author), Rietbroek, Roelof (author)We present a new approach to estimate time variations in J2. Those variations are represented as the sum of contributions from individual sources. This approach uses solely Gravity Recovery And Climate Experiment (GRACE) data and the geoid fingerprints of mass redistributions that take place both at the surface and in the interior of the solid...journal article 2019
- document
-
Wouters, B. (author), Gardner, Alex S. (author), Moholdt, Geir (author)Glaciers outside of the ice sheets are known to be important contributors to sea level rise. In this work, we provide an overview of changes in the mass of the world's glaciers, excluding those in Greenland and Antarctica, between 2002 and 2016, based on satellite gravimetry observations of the Gravity Recovery and Climate Experiment (GRACE)....journal article 2019
- document
-
Groh, Andreas (author), Horwath, Martin (author), Horvath, Alexander (author), Meister, Rakia (author), Wouters, B. (author), Ditmar, P.G. (author), Ran, J. (author), Klees, R. (author), Schrama, Ernst (author)Satellite gravimetry data acquired by the Gravity Recovery and Climate Experiment (GRACE) allows to derive the temporal evolution in ice mass for both the Antarctic Ice Sheet (AIS) and the Greenland Ice Sheet (GIS). Various algorithms have been used in a wide range of studies to generate Gravimetric Mass Balance (GMB) products. Results from...journal article 2019
- document
-
Ditmar, P.G. (author)Time-varying Stokes coefficients estimated from GRACE satellite data are routinely converted into mass anomalies at the Earth’s surface with the expression proposed for that purpose by Wahr et al. (J Geophys Res 103(B12):30,205–30,229, 1998). However, the results obtained with it represent mass transport at the spherical surface of 6378 km...journal article 2018
- document
-
Ditmar, P.G. (author), Tangdamrongsub, N. (author), Ran, J. (author), Klees, R. (author)We propose a technique to regularize a GRACE-based mass-anomaly time-series in order to (i) quantify the Standard Deviation (SD) of random noise in the data, and (ii) reduce the level of that noise. The proposed regularization functional minimizes the Month-to-month Year-to-year Double Differences (MYDD) of mass anomalies. As such, it does...journal article 2018
- document
-
Zhang, Hongyue (author), Sun, Y. (author)Annual cycles in the geocenter motion time series are primarily driven by mass changes in the Earth’s hydrologic system, which includes land hydrology, atmosphere, and oceans. Seasonal variations of the geocenter motion have been reliably determined according to Sun et al. (J Geophys Res Solid Earth 121(11):8352–8370, 2016) by combining the...journal article 2018