Earth's magnetic field (IGRF model)
[b, bdot] = CL_mod_geomagField(cjd, pos)
Computes the 3 components of the Earth's magnetic field according to IGRF model. Also returns their time derivatives.
Notes:
- The model coefficients are given at the beginning of year (January 1st). A linear interpolation is performed in order to determine the coefficients between 2 reference dates.
- The implicit time scale is assumed to be UTC but TREF can be considered as acceptable.
- The implicit reference frame is assumed to be ECF.
- %nan is returned for dates outside the range: [1900/1/1, 2020/1/1]. The results may be approximate for years beyond 2015.
- The model is inaccurate for radii greater than 6.6 Earth radii (around 42000 km).
Go to http://www.ngdc.noaa.gov/IAGA/vmod/igrf.html for more details on the model.
Date (modified julian day from 1950.0) at which the magnetic field is computed. (1xN or 1x1)
Position at which the magnetic field is computed, in cartesian coordinates [m]. (3xN or 3x1)
Magnetic field in cartesian coordinates [tesla]. (3xN)
Magnetic field time derivative in cartesian coordinates [tesla/sec]. (3xN)
CNES - DCT/SB
cjd = CL_dat_cal2cjd(2010:2013,1,1); // position - geodetic coordinates (lon,lat,alt) pos_ell = [0*%pi/180; 45*%pi/180; 0]; // magnetic field in topocentric North frame - nanotesla b = CL_mod_geomagField(cjd, CL_co_ell2car(pos_ell)); b_topo = CL_fr_topoNMat(pos_ell) * b * 1.e9 |  |  |