Ice and groundwater effects on long term polar motion (1979–2010)

Youm, Kookhyoun; Seo, Ki‐Weon; Jeon, Taehwan; Na, Sung-Ho; Chen, Jianli; Wilson, Clark R.

doi:10.1016/j.jog.2017.01.008

Cited by 16 publications

(15 citation statements)

References 45 publications

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“…This topic has been investigated in recent papers (e.g. Youm et al 2017). Indeed, since the beginning of the twentieth century, we have observed significant mass loss in both the Greenland and Antarctic Ice Sheets and glaciers, mainly as a result of a warmer climate (Adhikari and Ivins 2016;Velicogna et al 2014).…”

Section: Comparison Of Ham and Gaomentioning

confidence: 69%

Terrestrial water storage variations and their effect on polar motion

2018

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The role of continental water in polar motion excitation can be illustrated by determining Hydrological Angular Momentum calculated from terrestrial water storage (TWS). In this paper we compare global and regional changes in TWS computed using Coupled Model Intercomparison Project Phase 5 climate models, Global Land Data Assimilation System (GLDAS) land hydrology models and observations from the Gravity Recovery and Climate Experiment (GRACE) satellite mission. We also compare hydrological excitation functions derived from models with those obtained from the GRACE mission and the hydrological signal in observed polar motion excitation (the so-called geodetic residuals). The results confirm that GLDAS models of seasonal and non-seasonal TWS change are more consistent with GRACE data than climate models; on the other hand, none of the considered models are fully consistent with GRACE data or geodetic residuals. In turn, GRACE observations are most consistent with the non-seasonal hydrological signal in observed excitation. A detailed study of the contribution of different TWS components to the hydrological excitation function shows that soil moisture dominates.

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Section: Comparison Of Ham and Gaomentioning

confidence: 69%

Terrestrial water storage variations and their effect on polar motion

2018

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“…In this context, one critical aspect is to model the effect of climate variability on TWS changes. At this time, only global hydrological models and land surface models can provide long-term estimates of natural TWS variability; however, they are usually not calibrated against GRACE measurements and sometimes exhibit large biases in TWS amplitude (Schellekens et al, 2017;Zhang et al, 2017;Scanlon et al, 2018). Typically, only a small number of such model runs is available and exploring the uncertainty related to the use of different meteorological forcing datasets is not possible.…”

Section: Introductionmentioning

confidence: 99%

GRACE-REC: a reconstruction of climate-driven water storage changes over the last century

Humphrey

Gudmundsson

2019

Earth Syst. Sci. Data

181

191

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Abstract. The amount of water stored on continents is an important constraint for water mass and energy exchanges in the Earth system and exhibits large inter-annual variability at both local and continental scales. From 2002 to 2017, the satellites of the Gravity Recovery and Climate Experiment (GRACE) mission have observed changes in terrestrial water storage (TWS) with an unprecedented level of accuracy. In this paper, we use a statistical model trained with GRACE observations to reconstruct past climate-driven changes in TWS from historical and near-real-time meteorological datasets at daily and monthly scales. Unlike most hydrological models which represent water reservoirs individually (e.g., snow, soil moisture) and usually provide a single model run, the presented approach directly reconstructs total TWS changes and includes hundreds of ensemble members which can be used to quantify predictive uncertainty. We compare these data-driven TWS estimates with other independent evaluation datasets such as the sea level budget, large-scale water balance from atmospheric reanalysis, and in situ streamflow measurements. We find that the presented approach performs overall as well or better than a set of state-of-the-art global hydrological models (Water Resources Reanalysis version 2). We provide reconstructed TWS anomalies at a spatial resolution of 0.5∘, at both daily and monthly scales over the period 1901 to present, based on two different GRACE products and three different meteorological forcing datasets, resulting in six reconstructed TWS datasets of 100 ensemble members each. Possible user groups and applications include hydrological modeling and model benchmarking, sea level budget studies, assessments of long-term changes in the frequency of droughts, the analysis of climate signals in geodetic time series, and the interpretation of the data gap between the GRACE and GRACE Follow-On missions. The presented dataset is published at https://doi.org/10.6084/m9.figshare.7670849 (Humphrey and Gudmundsson, 2019) and updates will be published regularly.

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“…Polar motion (PM) is affected by a wide range of processes with different temporal variability ranging from several days to many decades [1]. Such disturbances include the gravitational influence of other celestial bodies, continuously changing mass distribution in the Earth's surficial fluids (atmosphere, oceans and land hydrosphere), the effects of core-mantle coupling, and also groundwater depletion and ice mass loss resulting from recent climate changes [2][3][4].…”

Section: Introductionmentioning

confidence: 99%

Evaluating Gravimetric Polar Motion Excitation Estimates from the RL06 GRACE Monthly-Mean Gravity Field Models

et al. 2020

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Over the last 15 years, the Gravity Recovery and Climate Experiment (GRACE) mission has provided measurements of temporal changes in mass redistribution at and within the Earth that affect polar motion. The newest generation of GRACE temporal models, are evaluated by conversion into the equatorial components of hydrological polar motion excitation and compared with the residuals of observed polar motion excitation derived from geodetic measurements of the pole coordinates. We analyze temporal variations of hydrological excitation series and decompose them into linear trends and seasonal and non-seasonal changes, with a particular focus on the spectral bands with periods of 1000–3000, 450–1000, 100–450, and 60–100 days. Hydrological and reduced geodetic excitation series are also analyzed in four separated time periods which are characterized by different accuracy of GRACE measurements. The level of agreement between hydrological and reduced geodetic excitation depends on the frequency band considered and is highest for interannual changes with periods of 1000–3000 days. We find that the CSR RL06, ITSG 2018 and CNES RL04 GRACE solutions provide the best agreement with reduced geodetic excitation for most of the oscillations investigated.

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Ice and groundwater effects on long term polar motion (1979–2010)

Cited by 16 publications

References 45 publications

Terrestrial water storage variations and their effect on polar motion

Terrestrial water storage variations and their effect on polar motion

GRACE-REC: a reconstruction of climate-driven water storage changes over the last century

Evaluating Gravimetric Polar Motion Excitation Estimates from the RL06 GRACE Monthly-Mean Gravity Field Models

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