Canada - Gravity data compilation

Description

The data used in this compilation come from the Canadian Gravity Database (CGDB), which is managed by the Canadian Geodetic Survey (CGS), Surveyor General Branch. CGDB includes more than 755 000 observations, including some 232 000 observations on land. The distribution of the land data represents an average of one gravity point per 40 km². The gravity maps, which are gridded to a 2-km interval with a blanking radius of 20 km, currently include data acquired between 1944 and 2015. CGS and partners continue to supplement the CGDB each year. The surveys are conducted using relative gravimeters that measure the gravity difference between two locations. On the landmass, gravity has been measured primarily using static gravimeters. Although measurements at some offshore locations have been collected using static gravimeters on the ocean floor, most are acquired using dynamic gravimeters aboard moving vessels. The relative nature of the gravimeters require that surveys be tied to base (control) stations with known absolute gravity. The base stations are part of the Canadian Gravity Standardization Network (CGSN), which is tied to the International Gravity Standardization Network 1971 (IGSN71). Today, the traditional base stations are being replaced by new base stations that are measured with an absolute gravimeter having an accuracy of 2µGal (2x10-8 m/s²). All relative gravity measurements are integrated into the IGSN71 datum to create a coherent dataset at the global scale. Normal (theoretical) gravity is calculated using the Geodetic Reference System 1980 (GRS80; https://doi.org/10.1007%2FS001900050278). Bouguer anomalies, which include reductions of the elevation and topographical mass to sea level, are calculated using a vertical gravity gradient of ~0.3086 mGal/m (change slightly with latitude and elevation) and a crustal density of 2670 kg/m³.

Resources

Name Format Description Link
Gravity anomalies, Canada (2 km grid) - English ZIP http://gdr.agg.nrcan.gc.ca/gdrdap/dap/index-eng.php?dapid=21
Horizontal gradient of gravity anomalies, Canada (2 km grid) - English ZIP http://gdr.agg.nrcan.gc.ca/gdrdap/dap/index-eng.php?dapid=73
First vertical derivative of gravity anomalies, Canada (2 km grid) - English ZIP http://gdr.agg.nrcan.gc.ca/gdrdap/dap/index-eng.php?dapid=74
First vertical derivative of gravity anomalies, Canada (2 km grid) - French ZIP http://gdr.agg.nrcan.gc.ca/gdrdap/dap/index-eng.php?dapid=74
Bouguer gravity anomalies, Canada (2 km grid) - English ZIP http://gdr.agg.nrcan.gc.ca/gdrdap/dap/index-eng.php?dapid=75
Isostatic residual of gravity anomalies (2 km grid), Canada - English ZIP http://gdr.agg.nrcan.gc.ca/gdrdap/dap/index-eng.php?dapid=76
Free air gravity anomalies, Canada (2 km grid) - English ZIP http://gdr.agg.nrcan.gc.ca/gdrdap/dap/index-eng.php?dapid=77
Observed gravity, Canada (2 km grid) - English ZIP http://gdr.agg.nrcan.gc.ca/gdrdap/dap/index-eng.php?dapid=78
Gravity anomalies, Canada (2 km grid) - French ZIP http://gdr.agg.nrcan.gc.ca/gdrdap/dap/index-fra.php?dapid=21
Horizontal gradient of gravity anomalies, Canada (2 km grid) - French ZIP http://gdr.agg.nrcan.gc.ca/gdrdap/dap/index-fra.php?dapid=73
Bouguer gravity anomalies, Canada (2 km grid) - French ZIP http://gdr.agg.nrcan.gc.ca/gdrdap/dap/index-fra.php?dapid=75
Isostatic residual of gravity anomalies (2 km grid), Canada - French ZIP http://gdr.agg.nrcan.gc.ca/gdrdap/dap/index-fra.php?dapid=76
Free air gravity anomalies, Canada (2 km grid) - French ZIP http://gdr.agg.nrcan.gc.ca/gdrdap/dap/index-fra.php?dapid=77
Observed gravity, Canada (2 km grid) - French ZIP http://gdr.agg.nrcan.gc.ca/gdrdap/dap/index-fra.php?dapid=78
Gravity anomalies description, Canada - French PDF http://gdr.agg.nrcan.gc.ca/gdrdap/pdf/Gravity_Anomaly_description.pdf
Gravity anomalies description, Canada - English PDF http://gdr.agg.nrcan.gc.ca/gdrdap/pdf/Gravity_Anomaly_description.pdf
Bouguer gravity anomalies description, Canada - English PDF http://gdr.agg.nrcan.gc.ca/gdrdap/pdf/Gravity_Bouguer_Anomaly_description.pdf
Bouguer gravity anomalies description, Canada - French PDF http://gdr.agg.nrcan.gc.ca/gdrdap/pdf/Gravity_Bouguer_Anomaly_description.pdf
Free air gravity anomalies description, Canada - English PDF http://gdr.agg.nrcan.gc.ca/gdrdap/pdf/Gravity_Free_Air_Anomaly_description.pdf
Free air gravity anomalies description, Canada - French PDF http://gdr.agg.nrcan.gc.ca/gdrdap/pdf/Gravity_Free_Air_Anomaly_description.pdf
Horizontal Gradient of Gravity Anomalies Description, Canada - English PDF http://gdr.agg.nrcan.gc.ca/gdrdap/pdf/Gravity_HGRAD_Bouguer_Anomaly_description.pdf
Horizontal Gradient of Gravity Anomalies Description, Canada - French PDF http://gdr.agg.nrcan.gc.ca/gdrdap/pdf/Gravity_HGRAD_Bouguer_Anomaly_description.pdf
Isostatic residual of gravity anomalies description, Canada - French PDF http://gdr.agg.nrcan.gc.ca/gdrdap/pdf/Gravity_Isostatic_Residual_Anomaly_description.pdf
Isostatic residual of gravity anomalies description, Canada - English PDF http://gdr.agg.nrcan.gc.ca/gdrdap/pdf/Gravity_Isostatic_Residual_Anomaly_description.pdf
Observed gravity description, Canada - English PDF http://gdr.agg.nrcan.gc.ca/gdrdap/pdf/Gravity_Observed_description.pdf
Observed gravity description, Canada - French PDF http://gdr.agg.nrcan.gc.ca/gdrdap/pdf/Gravity_Observed_description.pdf
Gravity point data file format and formulae description - French PDF http://gdr.agg.nrcan.gc.ca/gdrdap/pdf/Gravity_point_data_EF_description_2018.pdf
Gravity point data file format and formulae description - English PDF http://gdr.agg.nrcan.gc.ca/gdrdap/pdf/Gravity_point_data_EF_description_2018.pdf
First vertical derivative of gravity anomalies description, Canada - French PDF http://gdr.agg.nrcan.gc.ca/gdrdap/pdf/Gravity_VD1_Bouguer_Anomaly_description.pdf
First vertical derivative of gravity anomalies description, Canada - English PDF http://gdr.agg.nrcan.gc.ca/gdrdap/pdf/Gravity_VD1_Bouguer_Anomaly_description.pdf
Isostatic residual gravity anomaly map, Canada (Open File 8076) - English PDF https://doi.org/10.4095/299556
Isostatic residual gravity anomaly map, Canada (Open File 8076) - French PDF https://doi.org/10.4095/299556
Observed gravity map, Canada (Open File 8078) - English PDF https://doi.org/10.4095/299558
Observed gravity map, Canada (Open File 8078) - French PDF https://doi.org/10.4095/299558
Horizontal gradient of gravity anomalies map, Canada (Open File 8079) - French PDF https://doi.org/10.4095/299559
Horizontal gradient of gravity anomalies map, Canada (Open File 8079) - English PDF https://doi.org/10.4095/299559
First vertical derivative of gravity anomalies map, Canada (Open File 8080) - English PDF https://doi.org/10.4095/299560
First vertical derivative of gravity anomalies map, Canada (Open File 8080) - French PDF https://doi.org/10.4095/299560
Gravity anomaly map, Canada (Open File 8081) - French PDF https://doi.org/10.4095/299561
Gravity anomaly map, Canada (Open File 8081) - English PDF https://doi.org/10.4095/299561
Canadian Airborne Geophysical Database (CAGDB) Web service - French WMS http://wms.agg.nrcan.gc.ca/wms2/wms2.aspx?service=wms&version=1.3.0&request=GetCapabilities
Canadian Airborne Geophysical Database (CAGDB) Web service - English WMS http://wms.agg.nrcan.gc.ca/wms2/wms2.aspx?service=wms&version=1.3.0&request=GetCapabilities
Observed gravity description, Canada - French WMS http://wms.agg.nrcan.gc.ca/wms2/wms2.aspx?service=wms&version=1.3.0&request=GetCapabilities&layers=21,73,74,75,76,77,79,19
Observed gravity description, Canada - English WMS http://wms.agg.nrcan.gc.ca/wms2/wms2.aspx?service=wms&version=1.3.0&request=GetCapabilities&layers=21,73,74,75,76,77,79,19

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