Hydrological signals in polar motion excitation – Evidence after fifteen years of the GRACE mission

Nastula, Jolanta; Wińska, Małgorzata; Śliwińska, Justyna; Salstein, David A.

doi:10.1016/j.jog.2019.01.014

Cited by 17 publications

(52 citation statements)

References 32 publications

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“…The correlations between seasonal GAO and seasonal HAM from ITSG 2018 did not depend on the time period considered (Figure 3). Similar to amplitude and phase agreement shown in Figures 1 and 2 and results shown in previous works [26,[28][29][30]32,37,55], visibly better correlations were obtained for χ 2 . This was also observed for almost all hl-SST solutions.…”

Section: Seasonal Variationssupporting

confidence: 91%

“…Notably, the newest solutions from ITSG (GRACE AB ITSG v3 and Combined v3) visibly overestimated amplitudes of GAO in χ 2 , whereas GRACE AB CAS underestimated amplitudes of GAO in χ 2 . In general, better phase agreement with GAO was obtained for χ 2 component and this was also observed in previous works, e.g., in References [26,[28][29][30]32,37,55]. This resulted from spatial distribution of land and ocean that determine χ 2 to be more sensitive to mass changes over land, and χ 1 to be more sensitive to mass changes over ocean, ice, and glaciers.…”

Section: Seasonal Variationssupporting

confidence: 84%

“…2019, 11, 1784 4 of 19 to quantify mass-related PM excitation. The GRACE monthly solutions, based on precise range-rate measurements between two satellites (ll-SST), have been widely used for this purpose following extensive research in recent years [25][26][27][28][29][30][31]. Special interest has been placed on HAM, as AAM and OAM are well established [32][33][34][35][36][37][38].…”

Section: Introductionmentioning

confidence: 99%

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Determining and Evaluating the Hydrological Signal in Polar Motion Excitation from Gravity Field Models Obtained from Kinematic Orbits of LEO Satellites

Śliwińska

Nastula

2019

Remote Sensing

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This study evaluates the gravity field solutions based on high-low satellite-to-satellite tracking (hl-SST) of low-Earth-orbit (LEO) satellites: GRACE, Swarm, TerraSAR-X, TanDEM-X, MetOp-A, MetOp-B, and Jason 2, by converting them into hydrological polar motion excitation functions (or hydrological angular momentum (HAM)). The resulting HAM series are compared with the residuals of observed polar motion excitation (geodetic residuals, GAO) derived from precise geodetic measurements, and the HAM obtained from the GRACE ITSG 2018 solution. The findings indicate a large impact of orbital altitude and inclination on the accuracy of derived HAM. The HAM series obtained from Swarm data are found to be the most consistent with GAO. Visible differences are found in HAM obtained from GRACE and Swarm orbits and provided by different processing centres. The main reasons for such differences are likely to be different processing approaches and background models. The findings of this study provide important information on alternative data sets that may be used to provide continuous polar motion excitation observations, of which the Swarm solution provided by the Astronomical Institute, Czech Academy of Sciences, is the most accurate. However, further analysis is needed to determine which processing algorithms are most appropriate to obtain the best correspondence with GAO.

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Section: Seasonal Variationssupporting

confidence: 91%

Section: Seasonal Variationssupporting

confidence: 84%

Section: Introductionmentioning

confidence: 99%

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Determining and Evaluating the Hydrological Signal in Polar Motion Excitation from Gravity Field Models Obtained from Kinematic Orbits of LEO Satellites

Śliwińska

Nastula

2019

Remote Sensing

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“…The role of atmospheric and oceanic mass distribution on the global balance of Earth's angular momentum, described as atmospheric and oceanic angular momentum (AAM and OAM, respectively), is well established [7][8][9][10][11][12][13]. However, the role of the continental hydrosphere, referred to as hydrological angular momentum (HAM) or the hydrological excitation, is less clear as indications from different hydrological models do not agree well with each other [14][15][16][17][18]. Moreover, other geophysical effects, such as the consequences of co-and post-seismic deformations associated with large earthquakes [19], and the coupling between the Earth's core and the lower mantle [20,21], are often not considered in a rigorous way.…”

Section: Introductionmentioning

confidence: 99%

“…After removing tidal effects (atmospheric, ocean, solid Earth, and pole tides), as well as non-tidal atmospheric and oceanic contributions from the GRACE-based geopotential coefficients, the remaining signal is mostly an indication of the land hydrosphere [22], glacial isostatic adjustment (GIA) [23], barystatic sea-level contributions [24], and earthquake signatures [25]. GRACE-based PM excitation has been assessed before [8,12,15,16,[26][27][28][29][30], but considerable differences were found among the processing centers.…”

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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Assessment of degree-2 order-1 gravitational changes from GRACE and GRACE Follow-on, Earth rotation, satellite laser ranging, and models

Chen

Ries

Tapley

2021

J Geod

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We carry out a comprehensive analysis and assessment of degree-2 gravitational changes ΔC 21 , and ΔS 21 , estimated using the Gravity Recovery and Climate Experiment (GRACE) and GRACE Follow-On (GFO), satellite laser ranging (SLR), Earth Orientation Parameters (EOP), and geophysical models over the period April 2002-February 2020. The four independent estimates of ΔC 21 and ΔS 21 variations agree well over a broad band of frequencies. The GRACE/GFO Release 6 (RL06) solutions show major improvements over the previous RL05 solutions at both seasonal and intra-seasonal time scales, when compared with EOP and SLR estimates. Among the four independent estimates, highest correlation coefficients and smallest RMS residuals are found between GRACE/GFO and EOP estimates of ΔC 21 and ΔS 21 variations. GRACE/GFO and EOP ΔC 21 and ΔS 21 estimates exhibit slightly different trends, which are related to the implementation and interpretation of the pole tide correction in GRACE/GFO data processing. This study provides an important early validation of GFO ΔC 21 and ΔS 21 solutions, especially the new pole tide correction applied in GRACE/GFO RL06 solutions using independent estimates.

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Hydrological signals in polar motion excitation – Evidence after fifteen years of the GRACE mission

Cited by 17 publications

References 32 publications

Determining and Evaluating the Hydrological Signal in Polar Motion Excitation from Gravity Field Models Obtained from Kinematic Orbits of LEO Satellites

Determining and Evaluating the Hydrological Signal in Polar Motion Excitation from Gravity Field Models Obtained from Kinematic Orbits of LEO Satellites

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

Assessment of degree-2 order-1 gravitational changes from GRACE and GRACE Follow-on, Earth rotation, satellite laser ranging, and models

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