Significance of secular trends of mass variations determined from GRACE solutions

Steffen, Holger; Petrović, Svetozar; Müller, Jürgen; Schmidt, Roland; Wünsch, J.; Barthelmes, Franz; Kusche, Jürgen

doi:10.1016/j.jog.2009.09.029

Cited by 33 publications

(50 citation statements)

References 47 publications

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“…The GRACE gravity field solutions have been used to examine the rapidly decreasing ice mass in Antarctica (Chen et al 2006;Ramillien et al 2006;Sasgen et al 2007b;King et al 2012;Velicogna and Wahr 2013). The published ice mass trends derived from the GRACE monthly gravity fields are very diverse because they depend on the considered time spans, on the filters applied to reduce the noise, on the measures taken against signal leakage, and on model assumptions for signal separation of global isostatic adjustment and seasonal snow cover (Steffen et al 2009). Less noisy monthly gravity fields would be of major interest because consequently the applied smoothing and the related signal loss by leakage could be reduced.…”

Section: Mass Trends In Antarcticamentioning

confidence: 99%

“…Using the K -band and GPS measurements from the GRACE twin satellites (Dunn et al 2003), gravity fields at various spatial scales and temporal resolutions have been derived. They have been used for a wide range of geoscience research such as geodesy, hydrology, oceanography, atmo-B Ulrich Meyer ulrich.meyer@aiub.unibe.ch 1 Astronomical Institute, University of Bern, Sidlerstrasse 5, 3012 Bern, Switzerland spheric science, and glaciology (e.g., Güntner 2008;Johnson and Chambers 2013;Steffen et al 2009; and an overview in Wouters et al 2014).…”

Section: Introductionmentioning

confidence: 99%

“…Different processing strategies were applied, resulting in various noise characteristics of the individual solutions. Numerous studies compare subsets of the available monthly gravity fields in various geophysical applications such as ocean bottom pressure, ice mass change, and glacial isostatic adjustment (e.g., Chambers and Bonin 2012;Johnson and Chambers 2013;Sasgen et al 2007a;Steffen et al 2009). Sasgen et al (2007a) and Sakumura et al (2014) compared and combined the three official SDS and the GRGS gravity fields.…”

Section: Introductionmentioning

confidence: 99%

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Combination of GRACE monthly gravity field solutions from different processing strategies

Jean

Meyer

Jäggi

2018

J Geod

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We combine the publicly available GRACE monthly gravity field time series to produce gravity fields with reduced systematic errors. We first compare the monthly gravity fields in the spatial domain in terms of signal and noise. Then, we combine the individual gravity fields with comparable signal content, but diverse noise characteristics. We test five different weighting schemes: equal weights, non-iterative coefficient-wise, order-wise, or field-wise weights, and iterative field-wise weights applying variance component estimation (VCE). The combined solutions are evaluated in terms of signal and noise in the spectral and spatial domains. Compared to the individual contributions, they in general show lower noise. In case the noise characteristics of the individual solutions differ significantly, the weighted means are less noisy, compared to the arithmetic mean: The non-seasonal variability over the oceans is reduced by up to 7.7% and the root mean square (RMS) of the residuals of mass change estimates within Antarctic drainage basins is reduced by 18.1% on average. The field-wise weighting schemes in general show better performance, compared to the order-or coefficient-wise weighting schemes. The combination of the full set of considered time series results in lower noise levels, compared to the combination of a subset consisting of the official GRACE Science Data System gravity fields only: The RMS of coefficient-wise anomalies is smaller by up to 22.4% and the non-seasonal variability over the oceans by 25.4%. This study was performed in the frame of the European Gravity Service for Improved Emergency Management (EGSIEM; http://www.egsiem.eu) project. The gravity fields provided by the EGSIEM scientific combination service (ftp://ftp.aiub.unibe.ch/EGSIEM/) are combined, based on the weights derived by VCE as described in this article.

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Section: Mass Trends In Antarcticamentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Combination of GRACE monthly gravity field solutions from different processing strategies

Jean

Meyer

Jäggi

2018

J Geod

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“…Since the earliest GRACE studies, it has been, for instance, very common to refer to the phasing and amplitude of the seasonal cycle when comparing GRACE terrestrial water storage with other datasets such as model simulations (e.g., Tapley et al 2004b;Wahr et al 2004). As the temporal coverage of the GRACE record extended, more comprehensive studies also identified secular trends and inter-annual anomalies by separating the GRACE signal into long-term trends, periodical components and residual noise (Ramillien et al 2005;Schmidt et al 2008b;Steffen et al 2009). However, there is still no global overview on the relative magnitude and distribution of these features of temporal variability.…”

Section: Introductionmentioning

confidence: 99%

Assessing Global Water Storage Variability from GRACE: Trends, Seasonal Cycle, Subseasonal Anomalies and Extremes

Humphrey

Gudmundsson

Seneviratne

2016

Remote Sensing and Water Resources

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Throughout the past decade, the Gravity Recovery and Climate Experiment (GRACE) has given an unprecedented view on global variations in terrestrial water storage. While an increasing number of case studies have provided a rich overview on regional analyses, a global assessment on the dominant features of GRACE variability is still lacking. To address this, we survey key features of temporal variability in the GRACE record by decomposing gridded time series of monthly equivalent water height into linear trends, inter-annual, seasonal, and subseasonal (intra-annual) components. We provide an overview of the relative importance and spatial distribution of these components globally. A correlation analysis with precipitation and temperature reveals that both the inter-annual and subseasonal anomalies are tightly related to fluctuations in the atmospheric forcing. As a novelty, we show that for large regions of the world high-frequency anomalies in the monthly GRACE signal, which have been partly interpreted as noise, can be statistically reconstructed from daily precipitation once an adequate averaging filter is applied. This filter integrates the temporally decaying contribution of precipitation to the storage changes in any given month, including earlier precipitation. Finally, we also survey extreme dry anomalies in the GRACE record and relate them to documented drought events. This global assessment sets regional studies in a broader context and reveals phenomena that had not been documented so far.

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“…Another reason is a tide-alias error in the GRACE solutions. The error results in a spurious 161 day oscillation which grows towards the poles (Steffen et al, 2009).…”

Section: Error Estimation 241 Observation Errorsmentioning

confidence: 99%

Assimilation of GRACE-derived oceanic mass distributions with a global ocean circulation model

Saynisch

Bergmann-Wolf

Thomas

2014

J Geod

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To study the sub-seasonal distribution and generation of ocean mass anomalies, Gravity Recovery and Climate Experiment (GRACE) observations of daily and monthly resolution are assimilated into a global ocean circulation model with an ensemble based Kalman-Filter technique. The satellite gravimetry observations are processed to become time-variable fields of ocean mass distribution. Error budgets for the observations and the ocean model's initial state are estimated which contain the full covariance information. The consistency of the presented approach is demonstrated by increased agreement between GRACE observations and the ocean model. Furthermore, the simulations are compared with independent observations from 54 bottom pressure recorders. The assimilation improves the agreement to high-latitude recorders by up to 2 hPa. The improvements are caused by assimilation induced changes in the atmospheric wind forcing, i.e., quantities not directly observed by GRACE. Finally, the use of the developed Kalman-Filter approach as a destriping-filter to remove artificial noise contaminating the GRACE observations is presented.

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Significance of secular trends of mass variations determined from GRACE solutions

Cited by 33 publications

References 47 publications

Combination of GRACE monthly gravity field solutions from different processing strategies

Combination of GRACE monthly gravity field solutions from different processing strategies

Assessing Global Water Storage Variability from GRACE: Trends, Seasonal Cycle, Subseasonal Anomalies and Extremes

Assimilation of GRACE-derived oceanic mass distributions with a global ocean circulation model

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