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Canada - Gravity data compilation 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. 2010-09-10 2020-05-05 Natural Resources Canada nrcan.gsc-geosciencedata-donneesgeoscience-cgc.rncan@canada.ca Form DescriptorsNature and EnvironmentScience and TechnologyGeophysicsGeophysics; generalEarth sciences Gravity anomalies, Canada (2 km grid) - EnglishZIP http://gdr.agg.nrcan.gc.ca/gdrdap/dap/index-eng.php?dapid=21 Gravity anomalies, Canada (2 km grid) - FrenchZIP http://gdr.agg.nrcan.gc.ca/gdrdap/dap/index-fra.php?dapid=21 Free air gravity anomalies, Canada (2 km grid) - EnglishZIP http://gdr.agg.nrcan.gc.ca/gdrdap/dap/index-eng.php?dapid=77 Free air gravity anomalies, Canada (2 km grid) - FrenchZIP http://gdr.agg.nrcan.gc.ca/gdrdap/dap/index-fra.php?dapid=77 First vertical derivative of gravity anomalies, Canada (2 km grid) - FrenchZIP http://gdr.agg.nrcan.gc.ca/gdrdap/dap/index-eng.php?dapid=74 First vertical derivative of gravity anomalies, Canada (2 km grid) - EnglishZIP http://gdr.agg.nrcan.gc.ca/gdrdap/dap/index-eng.php?dapid=74 Bouguer gravity anomalies, Canada (2 km grid) - FrenchZIP http://gdr.agg.nrcan.gc.ca/gdrdap/dap/index-fra.php?dapid=75 Bouguer gravity anomalies, Canada (2 km grid) - EnglishZIP http://gdr.agg.nrcan.gc.ca/gdrdap/dap/index-eng.php?dapid=75 Canadian Airborne Geophysical Database (CAGDB) Web service - FrenchWMS http://wms.agg.nrcan.gc.ca/wms2/wms2.aspx?service=wms&version=1.3.0&request=GetCapabilities Canadian Airborne Geophysical Database (CAGDB) Web service - EnglishWMS http://wms.agg.nrcan.gc.ca/wms2/wms2.aspx?service=wms&version=1.3.0&request=GetCapabilities Gravity anomaly map, Canada (Open File 8081) - EnglishPDF https://doi.org/10.4095/299561 Gravity anomaly map, Canada (Open File 8081) - FrenchPDF https://doi.org/10.4095/299561 First vertical derivative of gravity anomalies map, Canada (Open File 8080) - EnglishPDF https://doi.org/10.4095/299560 First vertical derivative of gravity anomalies map, Canada (Open File 8080) - FrenchPDF https://doi.org/10.4095/299560 Isostatic residual gravity anomaly map, Canada (Open File 8076) - EnglishPDF https://doi.org/10.4095/299556 Isostatic residual gravity anomaly map, Canada (Open File 8076) - FrenchPDF https://doi.org/10.4095/299556 Horizontal gradient of gravity anomalies map, Canada (Open File 8079) - FrenchPDF https://doi.org/10.4095/299559 Horizontal gradient of gravity anomalies map, Canada (Open File 8079) - EnglishPDF https://doi.org/10.4095/299559 Observed gravity map, Canada (Open File 8078) - EnglishPDF https://doi.org/10.4095/299558 Observed gravity map, Canada (Open File 8078) - FrenchPDF https://doi.org/10.4095/299558 Horizontal gradient of gravity anomalies, Canada (2 km grid) - EnglishZIP http://gdr.agg.nrcan.gc.ca/gdrdap/dap/index-eng.php?dapid=73 Horizontal gradient of gravity anomalies, Canada (2 km grid) - FrenchZIP http://gdr.agg.nrcan.gc.ca/gdrdap/dap/index-fra.php?dapid=73 Isostatic residual of gravity anomalies (2 km grid), Canada - EnglishZIP http://gdr.agg.nrcan.gc.ca/gdrdap/dap/index-eng.php?dapid=76 Isostatic residual of gravity anomalies (2 km grid), Canada - FrenchZIP http://gdr.agg.nrcan.gc.ca/gdrdap/dap/index-fra.php?dapid=76 Observed gravity, Canada (2 km grid) - EnglishZIP http://gdr.agg.nrcan.gc.ca/gdrdap/dap/index-eng.php?dapid=78 Observed gravity, Canada (2 km grid) - FrenchZIP http://gdr.agg.nrcan.gc.ca/gdrdap/dap/index-fra.php?dapid=78 Bouguer gravity anomalies description, Canada - FrenchPDF http://gdr.agg.nrcan.gc.ca/gdrdap/pdf/Gravity_Bouguer_Anomaly_description.pdf Bouguer gravity anomalies description, Canada - EnglishPDF http://gdr.agg.nrcan.gc.ca/gdrdap/pdf/Gravity_Bouguer_Anomaly_description.pdf First vertical derivative of gravity anomalies description, Canada - EnglishPDF http://gdr.agg.nrcan.gc.ca/gdrdap/pdf/Gravity_VD1_Bouguer_Anomaly_description.pdf First vertical derivative of gravity anomalies description, Canada - FrenchPDF http://gdr.agg.nrcan.gc.ca/gdrdap/pdf/Gravity_VD1_Bouguer_Anomaly_description.pdf Free air gravity anomalies description, Canada - EnglishPDF http://gdr.agg.nrcan.gc.ca/gdrdap/pdf/Gravity_Free_Air_Anomaly_description.pdf Free air gravity anomalies description, Canada - FrenchPDF http://gdr.agg.nrcan.gc.ca/gdrdap/pdf/Gravity_Free_Air_Anomaly_description.pdf Gravity anomalies description, Canada - EnglishPDF http://gdr.agg.nrcan.gc.ca/gdrdap/pdf/Gravity_Anomaly_description.pdf Gravity anomalies description, Canada - FrenchPDF http://gdr.agg.nrcan.gc.ca/gdrdap/pdf/Gravity_Anomaly_description.pdf Gravity point data file format and formulae description - FrenchPDF http://gdr.agg.nrcan.gc.ca/gdrdap/pdf/Gravity_point_data_EF_description_2018.pdf Gravity point data file format and formulae description - EnglishPDF http://gdr.agg.nrcan.gc.ca/gdrdap/pdf/Gravity_point_data_EF_description_2018.pdf Horizontal Gradient of Gravity Anomalies Description, Canada - FrenchPDF http://gdr.agg.nrcan.gc.ca/gdrdap/pdf/Gravity_HGRAD_Bouguer_Anomaly_description.pdf Horizontal Gradient of Gravity Anomalies Description, Canada - EnglishPDF http://gdr.agg.nrcan.gc.ca/gdrdap/pdf/Gravity_HGRAD_Bouguer_Anomaly_description.pdf Isostatic residual of gravity anomalies description, Canada - EnglishPDF http://gdr.agg.nrcan.gc.ca/gdrdap/pdf/Gravity_Isostatic_Residual_Anomaly_description.pdf Isostatic residual of gravity anomalies description, Canada - FrenchPDF http://gdr.agg.nrcan.gc.ca/gdrdap/pdf/Gravity_Isostatic_Residual_Anomaly_description.pdf Observed gravity description, Canada - EnglishPDF http://gdr.agg.nrcan.gc.ca/gdrdap/pdf/Gravity_Observed_description.pdf Observed gravity description, Canada - FrenchPDF http://gdr.agg.nrcan.gc.ca/gdrdap/pdf/Gravity_Observed_description.pdf Observed gravity description, Canada - EnglishWMS 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 - FrenchWMS 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

Canada - Gravity data compilation

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

Resource Name Resource Type Format Language Links
Gravity anomalies, Canada (2 km grid) - English Dataset ZIP English Access
Gravity anomalies, Canada (2 km grid) - French Dataset ZIP French Access
Free air gravity anomalies, Canada (2 km grid) - English Dataset ZIP English Access
Free air gravity anomalies, Canada (2 km grid) - French Dataset ZIP French Access
First vertical derivative of gravity anomalies, Canada (2 km grid) - French Dataset ZIP French Access
First vertical derivative of gravity anomalies, Canada (2 km grid) - English Dataset ZIP English Access
Bouguer gravity anomalies, Canada (2 km grid) - French Dataset ZIP French Access
Bouguer gravity anomalies, Canada (2 km grid) - English Dataset ZIP English Access
Canadian Airborne Geophysical Database (CAGDB) Web service - French Web Service WMS French Access
Canadian Airborne Geophysical Database (CAGDB) Web service - English Web Service WMS English Access
Gravity anomaly map, Canada (Open File 8081) - English Guide PDF English Access
Gravity anomaly map, Canada (Open File 8081) - French Guide PDF French Access
First vertical derivative of gravity anomalies map, Canada (Open File 8080) - English Guide PDF English Access
First vertical derivative of gravity anomalies map, Canada (Open File 8080) - French Guide PDF French Access
Isostatic residual gravity anomaly map, Canada (Open File 8076) - English Guide PDF English Access
Isostatic residual gravity anomaly map, Canada (Open File 8076) - French Guide PDF French Access
Horizontal gradient of gravity anomalies map, Canada (Open File 8079) - French Guide PDF French Access
Horizontal gradient of gravity anomalies map, Canada (Open File 8079) - English Guide PDF English Access
Observed gravity map, Canada (Open File 8078) - English Guide PDF English Access
Observed gravity map, Canada (Open File 8078) - French Guide PDF French Access
Horizontal gradient of gravity anomalies, Canada (2 km grid) - English Dataset ZIP English Access
Horizontal gradient of gravity anomalies, Canada (2 km grid) - French Dataset ZIP French Access
Isostatic residual of gravity anomalies (2 km grid), Canada - English Dataset ZIP English Access
Isostatic residual of gravity anomalies (2 km grid), Canada - French Dataset ZIP French Access
Observed gravity, Canada (2 km grid) - English Dataset ZIP English Access
Observed gravity, Canada (2 km grid) - French Dataset ZIP French Access
Bouguer gravity anomalies description, Canada - French Guide PDF French Access
Bouguer gravity anomalies description, Canada - English Guide PDF English Access
First vertical derivative of gravity anomalies description, Canada - English Guide PDF English Access
First vertical derivative of gravity anomalies description, Canada - French Guide PDF French Access
Free air gravity anomalies description, Canada - English Guide PDF English Access
Free air gravity anomalies description, Canada - French Guide PDF French Access
Gravity anomalies description, Canada - English Guide PDF English Access
Gravity anomalies description, Canada - French Guide PDF French Access
Gravity point data file format and formulae description - French Guide PDF French Access
Gravity point data file format and formulae description - English Guide PDF English Access
Horizontal Gradient of Gravity Anomalies Description, Canada - French Guide PDF French Access
Horizontal Gradient of Gravity Anomalies Description, Canada - English Guide PDF English Access
Isostatic residual of gravity anomalies description, Canada - English Guide PDF English Access
Isostatic residual of gravity anomalies description, Canada - French Guide PDF French Access
Observed gravity description, Canada - English Guide PDF English Access
Observed gravity description, Canada - French Guide PDF French Access
Observed gravity description, Canada - English Dataset WMS English Access
Observed gravity description, Canada - French Dataset WMS French Access

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Electronic Mail Address: nrcan.gsc-geosciencedata-donneesgeoscience-cgc.rncan@canada.ca