Time‐variable gravity from GRACE: First results

Wahr, John; Swenson, Sean; Zlotnicki, Victor; Velicogna, I.

doi:10.1029/2004gl019779

Cited by 688 publications

(602 citation statements)

References 9 publications

(12 reference statements)

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“…The GRACE satellite mission measures variations of the Earth's gravity field which can be used to estimate changes in TWS at a spatial resolution of about 300 km [Wahr et al, 1998[Wahr et al, , 2004Tapley et al, 2004]. The water storage anomalies derived from GRACE encompass all water reservoirs, including groundwater, soil moisture, snowpack, land ice, surface water stored in rivers, lakes, and wetlands, as well as water stored in the biosphere.…”

Section: Grace Observationsmentioning

confidence: 99%

“…Launched in 2002, the Gravity Recovery and Climate Experiment (GRACE) mission has provided the first global observations of TWS changes [Wahr et al, 2004;Tapley et al, 2004]. As TWS is a key variable of the Earth's climate, impacting both surface water and energy budgets, these new observations have had important implications for the assessment of projected changes in the water cycle under current and future climate conditions [Famiglietti, 2014;Eicker et al, 2016;Reager et al, 2016].…”

Section: Introductionmentioning

confidence: 99%

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A global reconstruction of climate‐driven subdecadal water storage variability

Humphrey

Gudmundsson

Seneviratne

2017

Geophysical Research Letters

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Since 2002, the Gravity Recovery and Climate Experiment (GRACE) mission has provided unprecedented observations of global mass redistribution caused by hydrological processes. However, there are still few sources on pre‐2002 global terrestrial water storage (TWS). Classical approaches to retrieve past TWS rely on either land surface models (LSMs) or basin‐scale water balance calculations. Here we propose a new approach which statistically relates anomalies in atmospheric drivers to monthly GRACE anomalies. Gridded subdecadal TWS changes and time‐dependent uncertainty intervals are reconstructed for the period 1985–2015. Comparisons with model results demonstrate the performance and robustness of the derived data set, which represents a new and valuable source for studying subdecadal TWS variability, closing the ocean/land water budgets and assessing GRACE uncertainties. At midpoint between GRACE observations and LSM simulations, the statistical approach provides TWS estimates (doi:) that are essentially derived from observations and are based on a limited number of transparent model assumptions.

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Section: Grace Observationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A global reconstruction of climate‐driven subdecadal water storage variability

Humphrey

Gudmundsson

Seneviratne

2017

Geophysical Research Letters

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“…Since the start of the mission in 2002, measurements from the Gravity Recovery and Climate Experiment (GRACE) provide unprecedented estimates of changes in the terrestrial water storage (TWS) across large spatial domains (Tapley et al, 2004;Wahr et al, 2004). Due to their global coverage and independence from surface conditions, the data represent a unique opportunity to quantify spatio-temporal variations of the Earth's water resources (Alkama et al, 2010;Werth et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

Understanding terrestrial water storage variations in northern latitudes across scales

Trautmann

Koirala

Eicker

et al. 2018

Hydrol. Earth Syst. Sci.

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Abstract. The GRACE satellites provide signals of total terrestrial water storage (TWS) variations over large spatial domains at seasonal to inter-annual timescales. While the GRACE data have been extensively and successfully used to assess spatio-temporal changes in TWS, little effort has been made to quantify the relative contributions of snowpacks, soil moisture, and other components to the integrated TWS signal across northern latitudes, which is essential to gain a better insight into the underlying hydrological processes. Therefore, this study aims to assess which storage component dominates the spatio-temporal patterns of TWS variations in the humid regions of northern mid-to high latitudes.To do so, we constrained a rather parsimonious hydrological model with multiple state-of-the-art Earth observation products including GRACE TWS anomalies, estimates of snow water equivalent, evapotranspiration fluxes, and gridded runoff estimates. The optimized model demonstrates good agreement with observed hydrological spatio-temporal patterns and was used to assess the relative contributions of solid (snowpack) versus liquid (soil moisture, retained water) storage components to total TWS variations. In particular, we analysed whether the same storage component dominates TWS variations at seasonal and inter-annual temporal scales, and whether the dominating component is consistent across small to large spatial scales.Consistent with previous studies, we show that snow dynamics control seasonal TWS variations across all spatial scales in the northern mid-to high latitudes. In contrast, we find that inter-annual variations of TWS are dominated by liquid water storages at all spatial scales. The relative contribution of snow to inter-annual TWS variations, though, increases when the spatial domain over which the storages are averaged becomes larger. This is due to a stronger spatial coherence of snow dynamics that are mainly driven by temperature, as opposed to spatially more heterogeneous liquid water anomalies, that cancel out when averaged over a larger spatial domain. The findings first highlight the effectiveness of our model-data fusion approach that jointly interprets multiple Earth observation data streams with a simple model. Secondly, they reveal that the determinants of TWS variations in snow-affected northern latitudes are scale-dependent. In particular, they seem to be not merely driven by snow variability, but rather are determined by liquid water storages on interannual timescales. We conclude that inferred driving mechanisms of TWS cannot simply be transferred from one scale to another, which is of particular relevance for understanding the short-and long-term variability of water resources.

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“…The primary onboard payload, K-Band Ranging (KBR) instrument, measures the distance change between the center of mass of the GRACE satellites with a precision of better than 10 mm, for the purpose of measuring time-variable gravity fields with the spatial resolution of several hundredth km and temporal interval of one month [Tapley et al, 2004a[Tapley et al, , 2004b. Tapley et al [2004b] and Wahr et al [2004] describe the recovery of the terrestrial water mass variation from the GRACE monthly mean gravity estimates. The forward computation based on the time-series of spherical harmonic coefficients representing the monthly mean global geopotential fields is used to obtain monthly mean hydrology signals with an accuracy of $2 cm (in terms of water height equivalent) and resolution of $1000 km after applying the Gaussian smoothing [Wahr et al, 2004].…”

Section: Introductionmentioning

confidence: 99%

GRACE observations of M₂ and S₂ ocean tides underneath the Filchner‐Ronne and Larsen ice shelves, Antarctica

Han¹,

Shum²,

Matsumoto

2005

Geophysical Research Letters

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[1] By processing the GRACE satellite-to-satellite tracking data and estimating the temporal gravity fields regionally over the southern polar region with a 5-day interval, we observed M 2 and S 2 ocean tides underneath the Filchner-Ronne and Larsen ice shelves, Antarctica. Based on the predicted aliased periods, we extracted the M 2 and S 2 signals from the time-series of 5-daily mean GRACE regional gravity estimates. The GRACE observations agreed well with the predicted tides from the FES2004 and CATS02.01 models after smoothing the models to the commensurate spatial resolution as GRACE. Overall, the GRACE and the models agreed within 10$20% difference in the tidal amplitude and 20°in phase for both M 2 and S 2 . Our results suggest that GRACE provides valuable observations of ocean tides, with a spatial resolution as short as 300 km, over the remote area lacking of quality observations, such as the Antarctica ice shelves.

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Time‐variable gravity from GRACE: First results

Cited by 688 publications

References 9 publications

A global reconstruction of climate‐driven subdecadal water storage variability

A global reconstruction of climate‐driven subdecadal water storage variability

Understanding terrestrial water storage variations in northern latitudes across scales

GRACE observations of M₂ and S₂ ocean tides underneath the Filchner‐Ronne and Larsen ice shelves, Antarctica

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Time‐variable gravity from GRACE: First results

Cited by 688 publications

References 9 publications

A global reconstruction of climate‐driven subdecadal water storage variability

A global reconstruction of climate‐driven subdecadal water storage variability

Understanding terrestrial water storage variations in northern latitudes across scales

GRACE observations of M2 and S2 ocean tides underneath the Filchner‐Ronne and Larsen ice shelves, Antarctica

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GRACE observations of M₂ and S₂ ocean tides underneath the Filchner‐Ronne and Larsen ice shelves, Antarctica