Seasonal clockwise gyration and tilt of the Australian continent chasing the center of mass of the Earth's system from GPS and GRACE

Han, Shin‐Chan

doi:10.1002/2016jb013388

Cited by 8 publications

(15 citation statements)

References 39 publications

(65 reference statements)

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“…Nevertheless, the mean cumulative WRMS reductions shown here from all six gravity solutions are better than that from the latest results (maximum mean WRMS reduction up to 15%, see Table S3) published by Gu et al (2017) [9]. One more feature to be gleaned from Figure 1 is that no significant contributions come from degree beyond 30, which has been already demonstrated by Han (2016) [45].…”

Section: Full Signal Levelsupporting

confidence: 40%

Validation of the EGSIEM GRACE Gravity Fields Using GNSS Coordinate Timeseries and In-Situ Ocean Bottom Pressure Records

et al. 2018

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Over the 15 years of the Gravity Recovery and Climate Experiment (GRACE) mission, various data processing approaches were developed to derive time-series of global gravity fields based on sensor observations acquired from the two spacecrafts. In this paper, we compare GRACE-based mass anomalies provided by various processing groups against Global Navigation Satellite System (GNSS) station coordinate time-series and in-situ observations of ocean bottom pressure. In addition to the conventional GRACE-based global geopotential models from the main processing centers, we focus particularly on combined gravity field solutions generated within the Horizon2020 project European Gravity Service for Improved Emergency Management (EGSIEM). Although two validation techniques are fully independent from each other, it is demonstrated that they confirm each other to a large extent. Through the validation, we show that the EGSIEM combined long-term monthly solutions are comparable to CSR RL05 and ITSG2016, and better than the other three considered GRACE monthly solutions AIUB RL02, GFZ RL05a, and JPL RL05.1. Depending on the GNSS products, up to 25.6% mean Weighted Root-Mean-Square (WRMS) reduction is obtained when comparing GRACE to the ITRF2014 residuals over 236 GNSS stations. In addition, we also observe remarkable agreement at the annual period between GNSS and GRACE with up to 73% median WRMS reduction when comparing GRACE to the 312 EGSIEM-reprocessed GNSS time series. While the correspondence between GRACE and ocean bottom pressure data is overall much smaller due to lower signal to noise ratio over the oceans than over the continents, up to 50% agreement is found between them in some regions. The results fully confirm the conclusions found using GNSS.

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Section: Full Signal Levelsupporting

confidence: 40%

Validation of the EGSIEM GRACE Gravity Fields Using GNSS Coordinate Timeseries and In-Situ Ocean Bottom Pressure Records

et al. 2018

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“…The steady plate motion of ~7 cm/yr to the northeast relative to the mean lithosphere frame is the dominant horizontal motion in Australia [ Tregoning , ] and that has been characterized as a linear trend in the horizontal GPS time series. Han [] found that the effect of the global mean (“degree‐1”) surface mass distribution (i.e., geocenter motion) is evident in the Australian GPS data at a seasonal time scale. These undesired signals are removed from 3‐D GPS position data by detrending the horizontal GPS time series (to remove tectonic effect) and by correcting monthly mean estimates of the degree‐1 components from Han [] (to remove geocenter motion effect).…”

Section: Seasonal Mass Redistribution and Surface Deformationmentioning

confidence: 99%

“…Han [] found that the effect of the global mean (“degree‐1”) surface mass distribution (i.e., geocenter motion) is evident in the Australian GPS data at a seasonal time scale. These undesired signals are removed from 3‐D GPS position data by detrending the horizontal GPS time series (to remove tectonic effect) and by correcting monthly mean estimates of the degree‐1 components from Han [] (to remove geocenter motion effect). This makes GPS and GRACE data consistent in terms of signal content and reference frame.…”

Section: Seasonal Mass Redistribution and Surface Deformationmentioning

confidence: 99%

Elastic deformation of the Australian continent induced by seasonal water cycles and the 2010–2011 La Niña determined using GPS and GRACE

Han

2017

Geophysical Research Letters

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The solid Earth deforms elastically in response to changes in atmospheric, water, and ice mass load. I present geodetic (Gravity Recovery and Climate Experiment and GPS) observations of continental deformation at seasonal and interannual scales, responding to water and atmospheric cycles in Australia. In the southern summer, the central part of the Australian continent rises by a few millimeter and the north‐south perimeter lengthens by ~1 mm, induced by atmospheric unloading. In winter, the continent subsides and the perimeter shortens due to atmospheric loading. In autumn, increased soil moisture and groundwater result in 7 mm of subsidence in northern Australia and produce a positive slope trending southward. This trend reverses in spring. The La Niña precipitation in 2010–2011 produced widespread subsidence of >10 mm, followed by gradual uplift of 10 mm over the next 3–4 years, as water storage depletes slowly through evapotranspiration. The geodetic measurements find significant imbalance in the water cycle budget in Australia over 2010–2015.

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“…The time series are correlated by 0.70–0.79 between GPS and others and by 0.76–0.84 between GRACE and the model (for correlation computation, the daily GPS results were resampled at a monthly interval). The GRACE solutions are corrected for the degree 1 terms (geocenter components) when compared with GPS results (Han, ) to infer displacement and water storage change in a consistent reference frame. It should be noted that GPS inversion, GRACE, and GLDAS displacements are consistent in terms of spatial resolutions (degree and order up to 40) and that GRACE and the models are computed from the spherical harmonic synthesis while the GPS inversion results are from the Slepian synthesis.…”

Section: Results and Analysismentioning

confidence: 99%

GPS Recovery of Daily Hydrologic and Atmospheric Mass Variation: A Methodology and Results From the Australian Continent

Han

Razeghi

2017

JGR Solid Earth

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We present a methodology to invert a regional set of vertical displacement data from Global Positioning System (GPS) to determine the surface mass redistribution. It is assumed that GPS deformation is a result of the Earth's elastic response to the surface mass load of hydrology, atmosphere, and/or ocean. We develop an algorithm to estimate the spectral information of displacements from “regional” GPS data through regional spherical (Slepian) basis functions and apply the load Love numbers to estimate the mass load. The same approach is applied to determine global mass changes from “global” geopotential change data of Gravity Recovery and Climate Experiment (GRACE). We rigorously examine all systematic errors caused by various truncations (spherical harmonic series and Slepian series) and the smoothing constraint applied to the GPS inversion. We demonstrate the technique by processing 16 years of daily vertical motions determined from 114 GPS stations in Australia. The GPS‐inverted surface mass changes are validated against GRACE data, atmosphere and ocean models, and a land surface model. Seasonal and interannual terrestrial mass variations from GPS are in good agreement with GRACE data and the water storage models. The GPS recovery compares better with the water storage model around the smaller coastal basins than two different GRACE solutions. The submonthly mass changes from GPS provide meaningful results agreeing with atmospheric mass changes in central Australia. Finally, it is suggested to integrate GPS and GRACE data to draw a comprehensive picture of daily mass changes on different continents.

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Seasonal clockwise gyration and tilt of the Australian continent chasing the center of mass of the Earth's system from GPS and GRACE

Cited by 8 publications

References 39 publications

Validation of the EGSIEM GRACE Gravity Fields Using GNSS Coordinate Timeseries and In-Situ Ocean Bottom Pressure Records

Validation of the EGSIEM GRACE Gravity Fields Using GNSS Coordinate Timeseries and In-Situ Ocean Bottom Pressure Records

Elastic deformation of the Australian continent induced by seasonal water cycles and the 2010–2011 La Niña determined using GPS and GRACE

GPS Recovery of Daily Hydrologic and Atmospheric Mass Variation: A Methodology and Results From the Australian Continent

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