3:00 PM - 4:00 PM
[G03-P-04] Comparison of short-term iGrav superconducting gravimeter observations with local and global hydrological models
Hydrological mechanisms have been identified as the most complicated environmental effect on gravity signals. In this study, several sources of local and global hydrological observations are used and compared in order to obtain the 10 nms-2 accuracy for the iGrav's measurements needed in many geophysical applications. Six months of stationary measurements with Canada's first iGrav superconducting gravimeter (SG), collected from 31st October 2011 to 1st May 2012 at the University of Calgary, supported by A10 absolute measurements for calibration purposes, are processed and corrected for environmental interferences. After calibration, unwanted signals due to human activities, and natural environmental effects such as Earth tides, ocean loading, atmospheric pressure, polar motion, seismic events, etc., were removed from the iGrav's raw gravity signal. Residual gravity values increased by 50 nms-2, which agrees with the gravity effect of accumulated precipitation obtained by using an empirical admittance factor of 4.2 nms-2/cm. Groundwater level changes also demonstrated high correlation with the high frequency gravity variations. The gravity effect of groundwater level changes was calculated from a Bouguer slab model. The temporal variations of the integrated gravity signal are compared with filtered CSR GRACE monthly mass change solutions. Average soil moisture contributions from global land hydrology models, such as the GLDAS NOAH model with spatial resolution of 0.25 degrees and temporal resolution of 3 hours, are also analyzed. The results indicate that the monthly variations of groundwater storage effect in the iGrav's residual signal can be recovered perfectly by GRACE observations or local and global hydrological models with an accuracy of 8.5 nms-2.