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TitreA water storage anomaly in mid-continent North America from combined gravity and GPS observations
AuteurLambert, A; Huang, J; Henton, J A; Mazzotti, S; James, T S; Courtier, N; van der Kamp, G
SourceAmerican Geophysical Union 2012 Fall Meeting, abstracts; par American Geophysical Union; 2012.
LiensOnline - En ligne
Séries alt.Secteur des sciences de la Terre, Contribution externe 20120350
ÉditeurAmerican Geophysical Union
RéunionAmerican Geophysical Union 2012 Fall Meeting; San Fransico; US; décembre 3-7, 2012
Mediaen ligne; numérique
ProvinceManitoba; Saskatchewan
SNRC63; 73
Sujetsimagerie par satellite; anomalies gravimétriques; interprétations de la pesanteur; puits d'eau; géophysique
Résumé(disponible en anglais seulement)
Absolute gravity and GRACE satellite data have been combined with GPS data to identify a large-scale water storage anomaly on the Canadian prairies. Monthly GRACE data for the period 2002-2011 were used to produce a gravity rate map of the northern mid-continent. This map was corrected for glacial isostatic adjustment (GIA) using a GPS-based, vertical velocity map derived from 27 continuous and over 50 campaign sites, combined over the period 1996-2010. The vertical velocity map used to correct for GIA was first converted into a virtual gravity rate map using a linear relationship between surface gravity rate and vertical velocity (-0.16 microGal/mm), empirically derived from combined annual absolute gravity and continuous GPS observations at 7 sites outside the anomalous area. The corrected GRACE gravity rate map reveals a major mass rate anomaly with a water equivalent thickness rate of around 3 cm/yr and approximate dimensions of 600 km (N-S) and 800 km (E-W) centered on the Manitoba-Saskatchewan border. The amplitude and spatial extent of the anomaly are estimated by data inversion, taking into account the effect of elastic loading on the GPS-based GIA correction. The source of the anomaly is confirmed by records from deep observation wells in Saskatchewan to be an increase in total water content from 2002 to 2011, amounting to an overall water equivalent accumulation of around 27 cm over a wide area.