Magnetic Field - Secular Variation of the Declination Component for the Epoch 2010.0

Description:

This map layer shows isoporic lines (lines of equal annual change, or secular variation, in the declination of the Earth's magnetic field), derived from the International Geomagnetic Reference Field (IGRF) for the epoch 2010.0. Magnetic declination is the angle between true north and magnetic north (the direction of the magnetic field vector) in the horizontal plane. The change is measured in arc minutes per year. This layer is part of the 1997-2014 edition National Atlas of the United States. These data are intended for geographic display and analysis at the national level, and for large regional areas. The data should be displayed and analyzed at scales appropriate for 1:2,000,000-scale data. No responsibility is assumed by the National Atlas of the United States or the U.S. Geological Survey in the use of these data. National Atlas of the United States. (2011). Magnetic Field - Secular Variation of the Declination Component for the Epoch 2010.0. National Atlas of the United States. Available at: http://purl.stanford.edu/hc347kh4279. The declination component (D) and the secular variation (DSV, the time rate of change of D) of the IGRF change smoothly over most of the Earth with the exception of a region surrounding each of the geomagnetic poles. Near the geomagnetic poles, the isogonic lines (lines of constant declination) and isoporic lines crowd closer and closer together because at adjacent grid points (1 degree separation) the IGRF values of D and DSV upon which the lines are based vary extremely. For more information about the geomagnetic field, please visit <http://www.ngdc.noaa.gov/geomag/faqgeom.shtml>. This layer is presented in the WGS84 coordinate system for web display purposes. Downloadable data are provided in native coordinate system or projection.

Creator:

National Geophysical Data Center

Publisher:

National Atlas of the United States

Provider:

Stanford

Subject:

Geomagnetism, Magnetic declination, Geomagnetism--Secular variations, and Geoscientific Information

Temporal Coverage:

2010

Date Issued:

2011

Spatial Coverage:

United States, Alaska, Alabama, Arizona, Arkansas, Colorado, Connecticut, Delaware, Florida, Georgia, Hawaii, Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Maryland, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, Nevada, New Hampshire, New Jersey, New Mexico, New York (State), North Carolina, North Dakota, Ohio, Oklahoma, Oregon, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Utah, Vermont, Virginia, Washington (D.C.), Washington (State), West Virginia, Wisconsin, Wyoming, Puerto Rico, United States Virgin Islands, Cuba, North America, Mexico, and Canada

Access Rights:

Public

Format:

Shapefile

More details at:

https://purl.stanford.edu/hc347kh4279