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EMAG2v3 (MapServer)

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Service Description: 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:
  1. A consistent altitude of 4 km (referred to as Upward Continued)
  2. Anomaly altitude at Sea Level
This map service has several sub-layers:The magnetic anomaly values in nanotesla (nT) are displayed using the color ramp below:
EMAG2v3 color scale

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).There are four related ArcGIS services providing access to EMAG2v3:

Map Name: Layers


All Layers and Tables

Dynamic Legend

Dynamic All Layers

Layers: Description:

Copyright Text: NOAA National Centers for Environmental Information (NCEI)

Spatial Reference: 4326  (4326)

Single Fused Map Cache: false

Initial Extent: Full Extent: Units: esriDecimalDegrees


Document Info: Supports Dynamic Layers: true

MaxRecordCount: 1000

MaxImageHeight: 4096

MaxImageWidth: 4096

Supported Query Formats: JSON, AMF, geoJSON

Min Scale: 0

Max Scale: 0

Supports Datum Transformation: true

Child Resources:   Info   Dynamic Layer

Supported Operations:   Export Map   Identify   QueryDomains   Find   Return Updates