<abstract xmlns="http://www.w3.org/1999/xhtml">

The main aim of this study is to evaluate the usefulness of Institute of Geodesy at Graz University of Technology (ITSG) daily gravity field models in the determination of hydrological angular momentum (HAM) at nonseasonal time scales. We compared the equatorial components (χ1 and χ2) of HAM calculated with the ITSG daily gravity field models (ITSG-Gravity Recovery and Climate Experiment [ITSG-GRACE] 2016 and ITSG-GRACE 2018) with HAM and sea-level angular momentum (SLAM) from hydrological land surface discharge model (LSDM) and the hydrological signal in the polar motion excitation (known as geodetic residuals [GAO]). Data from ITSG have a daily temporal resolution and allow us to determine oscillations with higher frequencies than the more commonly used monthly data. We limited our study to the period between 2004 and 2011 because of the gaps in GRACE observations before and after this period. We evaluated HAM obtained from ITSG GRACE models in spectral and time domains and determined the amplitude spectra of the analyzed series in the spectral range from 2 to 120 days. Our analyses confirm the existence of a sub-monthly signal in the HAM series determined from ITSG daily data. We observed a similar signal in LSDM-based HAM, but with notably weaker amplitudes. We also observed common peaks around 14 days in the amplitude spectra for the GAO- and ITSG-based series, which may be related to the Earth’s tides. ITSG daily gravity field models can be useful to determine the equatorial components of HAM at nonseasonal time scales.
</abstract>

The main aim of this study is to evaluate the usefulness of Institute of Geodesy at Graz University of Technology (ITSG) daily gravity field models in the determination of hydrological angular momentum (HAM) at nonseasonal time scales. We compared the equatorial components (χ1 and χ2) of HAM calculated with the ITSG daily gravity field models (ITSG-Gravity Recovery and Climate Experiment [ITSG-GRACE] 2016 and ITSG-GRACE 2018) with HAM and sea-level angular momentum (SLAM) from hydrological land surface discharge model (LSDM) and the hydrological signal in the polar motion excitation (known as geodetic residuals [GAO]). Data from ITSG have a daily temporal resolution and allow us to determine oscillations with higher frequencies than the more commonly used monthly data. We limited our study to the period between 2004 and 2011 because of the gaps in GRACE observations before and after this period. We evaluated HAM obtained from ITSG GRACE models in spectral and time domains and determined the amplitude spectra of the analyzed series in the spectral range from 2 to 120 days. Our analyses confirm the existence of a sub-monthly signal in the HAM series determined from ITSG daily data. We observed a similar signal in LSDM-based HAM, but with notably weaker amplitudes. We also observed common peaks around 14 days in the amplitude spectra for the GAO- and ITSG-based series, which may be related to the Earth’s tides. ITSG daily gravity field models can be useful to determine the equatorial components of HAM at nonseasonal time scales.

Analysis of The Itsg-Grace Daily Models in The Determination of Polar Motion Excitation Function

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This work is licensed under the Creative Commons Attribution 4.0 International License.

The main aim of this study is to evaluate the usefulness of Institute of Geodesy at Graz University of Technology (ITSG) daily gravity field models in the...

Analysis of The Itsg-Grace Daily Models in The Determination of Polar Motion Excitation Function

Published Online: Oct 10, 2023

Page range: 105 - 121

Received: Mar 13, 2023

Accepted: Jul 10, 2023

DOI: https://doi.org/10.2478/arsa-2023-0008

Keywords
GRACE, hydrological angular momentum, Earth rotation, polar motion excitation

© 2023 Aleksander Partyka et al., published by Sciendo

This work is licensed under the Creative Commons Attribution 4.0 International License.

Analysis of The Itsg-Grace Daily Models in The Determination of Polar Motion Excitation Function

Published Online: Oct 10, 2023

Page range: 105 - 121

Received: Mar 13, 2023

Accepted: Jul 10, 2023

DOI: https://doi.org/10.2478/arsa-2023-0008

KeywordsGRACE, hydrological angular momentum, Earth rotation, polar motion excitation

© 2023 Aleksander Partyka et al., published by Sciendo

This work is licensed under the Creative Commons Attribution 4.0 International License.

Keywords
GRACE, hydrological angular momentum, Earth rotation, polar motion excitation