This service enables computation of a set of the main geomagnetic
field model parameters and transformation from the GEOcentric spherical
(geographic) coordinates to the Corrected GeoMagnetic (CGM) coordinates
and vice versa. The algorithm is solely based on the DGRF/IGRF
geomagnetic field models for Epochs 1900-2010. The B-min approach is
applied to calculate CGM coordinates through the near-equator area
where the definition of CGM coordinates is invalid. However, GEO <--> CGM
transformations are not performed at certain regions where the CGM equator
cannot be defined at all.
The input parameter are:
- Geocentric or Corrected GeoMagnetic Latitude and Longitude
- Altitude above the 1-Re (6371.2 km) surface: 40,000 km limit
- Year for Definitive/International Geomagnetic Reference Field
(DGRF/IGRF) models from 1900 to 2010
The following output parameters are calculated:
- GEOCENTRIC, CGM, and footprint coordinates of a given point
- DGRF/IGRF magnetic field components H (nT), D (deg.), and
Z (nT) at this point
- Geocentric and CGM coordinates of the magnetically conjugate
point and the magnetic field line footprint
- Apex of the magnetic field line: the point at a maximum distance
- UT (hh:mm) at time when given point is at midnight (MLT)
- Meridian_angle: the azimuth along a great-circle arc to the North
(South) CGM pole measured from the geographic North (South)
meridian; positive to East (West)
- Oval_angle: the angle between local tangents to the CGM and
geographic (geocentric) latitudes;
Please acknowledge SPDF/Modelweb in publications that use data and plots from this interface.
Brief Description of CGM and Associated MLT Definition
Use Form 1 OR Form 2 Below
Query Form 1: Latitude/Longitude
Query Form 2: Image Map (only GEO ==> CGM)
If you have any questions/comments about this algorithm or
computer code, contact:
Dr. Vladimir Papitashvili, E-mail:
papita@umich.edu, Space
Physics Research Laboratory, The University of Michigan, 2455
Hayward St., Ann Arbor, MI 48109-2143
Dr. Natalia Papitashvili, E-mail:
Natalia.E.Papitashvili@gsfc.nasa.gov, Mail Code 672,
NASA/Goddard Space Flight Center, Greenbelt, MD 20771
NASA Official: Dr. Robert McGuire, Head of the Space Physics Data Facility