Item

Abstract

Gravimetric excitation of polar motion (PM) can be determined from the models of Earth’s gravity field variations based on observations of Gravity Recovery and Climate Experiment (GRACE) andits successor GRACE Follow-On (GRACE-FO). Such excitation reflects mainly the impact of continental hydrosphere and cryosphere on PM variation and is usually described with series of hydrological plus cryospheric angular momentum (HAM+CAM).Previous research on the use of GRACE/GRACE-FO data for HAM+CAM analysis focused on exploiting for this purpose more popular monthly solutions. In this study, in contrast to former analyses, we use daily and 10-day data provided by the Institute of Geodesy at Graz University of Technology (ITSG) and Centre National d’Études Spatiales (CNES) to study PM excitation at sub-monthly time scales. We analyse several oscillations in HAM+CAM series obtained from GRACE/GRACE-FO and compare them with geodetic excitation reduced bythe influence of the atmosphere and oceans (so-called geodetic residuals, GAO) and with HAM determined from hydrological models. This analysis aims to check whether the daily and 10-day solutions carry any additional information about PM that is not provided by monthly data.We show that sub-monthly GRACE/GRACE-FO data can be useful especially for the analysis of HAM+CAM changes with periods above 20 days. Despite underestimating GAO variability, HAM+CAM series are quite well correlated with GAO, especially in terms of 10-day data.