The long observational history of the Canadian Gravity Standardisation network-CGSN along with repeated high precision absolute gravity measurements have been considered carefully in the estimation of the time rate of change of gravity (g-dot) in Canada that is dominated by the glacial isostatic adjustment-GIA. We presented the first results in 2003 but a decade later more absolute gravity observations have been taken that provide significant new information on g-dot and GIA. We have reconsidered the inversion of the old gravity measurements with the following new additions: a) reprocessed longer absolute gravity series to estimate more accurate g-dot at a reference epoch with respect to which all observations are inverted, b) addition of two new absolute gravity stations for a total of eight that serve as weighted g-dot constraints to the data inversion, c) addition of 225 new relative gravity observations in the region W-NW of Hudson Bay, d) hydrological viscoelastic loading effect reduction driven by WGHM global model and e) regional constraints on g-dot that effectively filter out high spatial frequency variation of g-dot. The new and improved g-dot pattern in Canada compares very favourably with the h-dot signature that has been derived from vertical crustal movements and modern GPS observations. Comparisons are also made to the GIA signature determined from GRACE.
|American Geophysical Union, Fall Meeting 2012
|Published - ديسمبر 1 2012