scholarly journals Regional acceleration in ice mass loss from Greenland and Antarctica using GRACE time-variable gravity data

2014 ◽  
Vol 41 (22) ◽  
pp. 8130-8137 ◽  
Author(s):  
I. Velicogna ◽  
T. C. Sutterley ◽  
M. R. van den Broeke
Keyword(s):  
Mass Loss ◽  
Gravity Data ◽  
Time Variable ◽  
Time Variable Gravity ◽  
Variable Gravity

scholarly journals Supporting large-scale hydrogeological monitoring and modelling by time-variable gravity data

2006 ◽  
Vol 15 (1) ◽  
pp. 167-170 ◽  
Author(s):  
Andreas Güntner ◽  
Roland Schmidt ◽  
Petra Döll
Keyword(s):  
Large Scale ◽  
Gravity Data ◽  
Time Variable ◽  
Time Variable Gravity ◽  
Variable Gravity

scholarly journals Mass Balance of Novaya Zemlya Archipelago, Russian High Arctic, using Time-Variable Gravity from GRACE and Altimetry Data from ICESat and Cryosat-2

2018 ◽  
Author(s):  
Enrico Ciracì ◽  
Isabella Velicogna ◽  
Tyler Clark Sutterley
Keyword(s):  
Mass Loss ◽  
Mass Balance ◽  
High Arctic ◽  
Time Variable ◽  
Altimetry Data ◽  
Novaya Zemlya Archipelago ◽  
Novaya Zemlya ◽  
Time Variable Gravity ◽  
Variable Gravity

We examine the mass balance of the glaciers in the Novaya Zemlya Archipelago, located in the Russian High Arctic using time series of time-variable gravity from the NASA/DLR Gravity Recovery and Climate Experiment (GRACE) mission, laser altimetry data from the NASA Ice Cloud and land Elevation Satellite (ICESat) mission, and radar altimetry data from the ESA CryoSat-2 mission. We present a new algorithm for detecting changes in glacier elevation from these satellite altimetry data and evaluate its performance in the case Novaya Zemlya by comparing the results with GRACE. We find that the mass loss of Novaya Zemlya increased from 10±5 Gt/yr over 2003-2009 to 14±4 Gt/yr over 2010-2016, with a brief period of near mass balance between 2009 and 2011. The results are consistent across the gravimetric and altimetric methods. Furthermore, the analysis of elevation change from CryoSat-2 indicates that 60\% of the mass loss occurs at low elevation, where thinning rates are highest. We also find that marine-terminating glaciers in Novaya Zemlya are thinning significantly faster than land-terminating glaciers, which indicates an important role of ice dynamics of marine-terminating glaciers. We posit that the glacier changes have been caused by changes in atmospheric and ocean temperatures. We find that the increase in mass loss after 2010 is associated with a warming in air temperatures, which increased the surface melt rates. There is no enough information on the ocean temperature at the front of the glaciers to conclude on the role of the ocean, but we posit that the temperature of subsurface ocean waters must have increased during the observation period.

Water Storage Changes in Three Gorges Water Systems Area Inferred from Grace Time-Variable Gravity Data

2007 ◽  
Vol 50 (3) ◽  
pp. 650-657 ◽  
Author(s):  
Han-Sheng WANG ◽  
Zhi-Yong WANG ◽  
Xu-Dong YUAN ◽  
Patrick Wu ◽  
Elena Rangelova
Keyword(s):  
Gravity Data ◽  
Water Storage ◽  
Water Systems ◽  
Time Variable ◽  
Three Gorges ◽  
Time Variable Gravity ◽  
Variable Gravity

Spherical and ellipsoidal surface mass change from GRACE time-variable gravity data

2020 ◽  
Author(s):  
Michal Šprlák ◽  
Khosro Ghobadi-Far ◽  
Shin-Chan Han ◽  
Pavel Novák
Keyword(s):  
Gravity Field ◽  
Gravitational Potential ◽  
Gravity Data ◽  
Time Variable ◽  
Mass Change ◽  
Spherical Approximation ◽  
Surface Mass ◽  
Time Variable Gravity ◽  
The Earth ◽  
Variable Gravity

<p>The problem of estimating mass redistribution from temporal variations of the Earth’s gravity field, such as those observed by GRACE, is non-unique. By approximating the Earth’s surface by a sphere, surface mass change can be uniquely determined from time-variable gravity data. Conventionally, the spherical approach of Wahr et al. (1998) is employed for computing the surface mass change caused, for example, by terrestrial water and glaciers. The accuracy of the GRACE Level 2 time-variable gravity data has improved due to updated background geophysical models or enhanced data processing. Moreover, time series analysis of ∼15 years of GRACE observations allows for determining inter-annual and seasonal changes with a significantly higher accuracy than individual monthly fields. Thus, the improved time-variable gravity data might not tolerate the spherical approximation introduced by Wahr et al. (1998).</p><p>A spheroid (an ellipsoid of revolution) represents a closer approximation of the Earth than a sphere, particularly in polar regions. Motivated by this fact, we develop a rigorous method for determining surface mass change on a spheroid. Our mathematical treatment is fully ellipsoidal as we concisely use Jacobi ellipsoidal coordinates and exploit the corresponding series expansions of the gravitational potential and of the surface mass. We provide a unique one-to-one relationship between the ellipsoidal spectrum of the surface mass and the ellipsoidal spectrum of the gravitational potential. This ellipsoidal spectral formula is more general and embeds the spherical approach by Wahr et al. (1998) as a special case. We also quantify the differences between the spherical and ellipsoidal approximations numerically by calculating the surface mass change rate in Antarctica and Greenland.</p><p> </p><p>References:</p><p>Wahr J, Molenaar M, Bryan F (1998) Time variability of the Earth’s gravity field: Hydrological and oceanic effects and their possible detection using GRACE. Journal of Geophysical Research: Solid Earth, 103(B12), 30205-30229.</p>

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