EMAG2v3: Earth Magnetic Anomaly Grid at 2-arc-minute Resolution, Version 3NOAA's National Centers for Environmental Information (NCEI)EMAG2v3: the Earth Magnetic Anomaly Grid (2 arc-minute resolution), version 3 is compiled from satellite, ship, and airborne magnetic measurements. Magnetic anomalies result from geologic features enhancing or depressing the local magnetic field. These maps increase knowledge of subsurface structure and composition of the Earth's crust. Global magnetic anomaly grids are used for resource exploration, navigation where GPS is unavailable (submarine, directional drilling, etc.), and for studying the evolution of the lithosphere.The 2017 release of the EMAG2v3 utilizes updated precompiled grids and a revised process for accurately incorporating the long-wavelength anomalies, as modeled by the satellite-based MF7 lithospheric field model. It is an update from the previous EMAG2v3 released by NCEI in 2016. EMAG2v3 further differs from the previous EMAG2 (version 2), which relied on an ocean age model to interpolate anomalies into non-existent data areas and on the earlier MF6 model. EMAG2v3 relies solely on the data available. As a result, EMAG2v3 better represents the complexity of these anomalies in oceanic regions and accurately reflects areas where no data has been collected. The current version reports anomalies in two ways:A consistent altitude of 4 km (referred to as Upward Continued)Anomaly altitude at Sea LevelThe magnetic anomaly values in nanotesla (nT) are displayed using the color ramp below:Tips for using this web map:View the legend or toggle layers on/off with the buttons in the upper-right.Click on the map to see a popup reporting the data value at that location. Click on the arrow scroll through values for the Upward Continued (UpCont), Sea Level, and Error grids.The latitude/longitude of the mouse pointer is displayed in the lower-left.The EMAG2 dataset illustrates Earth evolution (plate tectonics and crustal interaction with the deep mantle). Distinct patterns and magnetic signatures are attributed to the formation (seafloor spreading) and destruction (subduction zones) of oceanic crust, and the formation of continental crust by accretion of various terranes to cratonic areas and large scale volcanism (both on continents and oceans).Magnetization is weaker at the equator and stronger at high latitudes, reflecting the strength of the ambient geomagnetic field, which induces magnetization in rocksStripes of alternating magnetization in the oceans are due to sea floor spreading and the alternating polarity of the geomagnetic fieldVery old crust (North American Shield, Baltic Shield, Siberian Craton) have strongest magnetization, seen as dark shades of blueThere are four related ArcGIS services providing access to EMAG2v3:Color shaded relief image (tiled, Web Mercator projection)Color shaded relief image (tiled, WGS84 geographic)Multi-layer map serviceImage service (data values)

EMAG2v3: Earth Magnetic Anomaly Grid at 2-arc-minute Resolution, Version 3NOAA's National Centers for Environmental Information (NCEI)EMAG2v3: the Earth Magnetic Anomaly Grid (2 arc-minute resolution), version 3 is compiled from satellite, ship, and airborne magnetic measurements. Magnetic anomalies result from geologic features enhancing or depressing the local magnetic field. These maps increase knowledge of subsurface structure and composition of the Earth's crust. Global magnetic anomaly grids are used for resource exploration, navigation where GPS is unavailable (submarine, directional drilling, etc.), and for studying the evolution of the lithosphere.The 2017 release of the EMAG2v3 utilizes updated precompiled grids and a revised process for accurately incorporating the long-wavelength anomalies, as modeled by the satellite-based MF7 lithospheric field model. It is an update from the previous EMAG2v3 released by NCEI in 2016. EMAG2v3 further differs from the previous EMAG2 (version 2), which relied on an ocean age model to interpolate anomalies into non-existent data areas and on the earlier MF6 model. EMAG2v3 relies solely on the data available. As a result, EMAG2v3 better represents the complexity of these anomalies in oceanic regions and accurately reflects areas where no data has been collected. The current version reports anomalies in two ways:A consistent altitude of 4 km (referred to as Upward Continued)Anomaly altitude at Sea LevelThe magnetic anomaly values in nanotesla (nT) are displayed using the color ramp below:Tips for using this web map:View the legend or toggle layers on/off with the buttons in the upper-right.Click on the map to see a popup reporting the data value at that location. Click on the arrow scroll through values for the Upward Continued (UpCont), Sea Level, and Error grids.The latitude/longitude of the mouse pointer is displayed in the lower-left.The EMAG2 dataset illustrates Earth evolution (plate tectonics and crustal interaction with the deep mantle). Distinct patterns and magnetic signatures are attributed to the formation (seafloor spreading) and destruction (subduction zones) of oceanic crust, and the formation of continental crust by accretion of various terranes to cratonic areas and large scale volcanism (both on continents and oceans).Magnetization is weaker at the equator and stronger at high latitudes, reflecting the strength of the ambient geomagnetic field, which induces magnetization in rocksStripes of alternating magnetization in the oceans are due to sea floor spreading and the alternating polarity of the geomagnetic fieldVery old crust (North American Shield, Baltic Shield, Siberian Craton) have strongest magnetization, seen as dark shades of blueThere are four related ArcGIS services providing access to EMAG2v3:Color shaded relief image (tiled, Web Mercator projection)Color shaded relief image (tiled, WGS84 geographic)Multi-layer map serviceImage service (data values)