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# igrf11magm

Calculate Earth's magnetic field using 11th generation of International Geomagnetic Reference Field

## Syntax

[mag_field_vector, hor_intensity, declination, inclination, total_intensity, mag_field_sec_variation, sec_variation_horizontal, sec_variation_declination, sec_variation_inclination, sec_variation_total] = igrf11magm(height, latitude, longitude, decimal_year)

## Description

[mag_field_vector, hor_intensity, declination, inclination, total_intensity, mag_field_sec_variation, sec_variation_horizontal, sec_variation_declination, sec_variation_inclination, sec_variation_total] = igrf11magm(height, latitude, longitude, decimal_year) calculates the Earth's magnetic field and the secular variation at a specific location and time. This function uses the 11th generation of the International Geomagnetic Reference Field (IGRF-11).

## Input Arguments

 height Scalar distance, in meters, from the surface of the Earth. latitude Scalar geodetic latitude, in degrees. North latitude is positive, south latitude is negative. longitude Scalar geodetic longitude, in degrees. East longitude is positive, west longitude is negative. decimal_year Scalar year, in decimal format. This value is the desired year to include any fraction of the year that has already passed.

## Output Arguments

 mag_field_vector Magnetic field vector, in nanotesla (nT). Z is the vertical component (+ve down). hor_intensity Horizontal intensity, in nanotesla (nT). declination Declination, in degrees (+ve east). inclination Inclination, in degrees (+ve down). total_intensity Total intensity, in nanotesla (nT). mag_field_sec_variation Secular variation in magnetic field vector, in nT/year. Z is the vertical component (+ve down). sec_variation_horizontal Secular variation in horizontal intensity, in nT/year. sec_variation_declination Secular variation in declination, in minutes/year (+ve east). sec_variation_inclination Secular variation in inclination, in minutes/year (+ve down). sec_variation_total Secular variation in total intensity, in nT/year.

## Examples

Calculate the magnetic model 1000 meters over Natick, Massachusetts on July 4, 2005 using IGRF-11:

[XYZ, H, DEC, DIP, F] = igrf11magm(1000, 42.283, -71.35, ...
decyear(2005,7,4))

XYZ =

1.0e+004 *

1.8982   -0.5176    4.9558

H =

1.9675e+004

DEC =

-15.2524

DIP =

68.3467

F =

5.3320e+004

expand all

### Tips

• The igrf11magm function is valid between the heights of –1000 meters to 600000 meters.

• The igrf11magm function is valid between the years of 1900 and 2015.

• This function has the limitations of the International Geomagnetic Reference Field (IGRF).

## References

Lowes, F. J. "The International Geomagnetic Reference Field: A 'Health' Warning." January, 2010. http://www.ngdc.noaa.gov/IAGA/vmod/igrfhw.html

Blakely, R. J. Potential Theory in Gravity & Magnetic Applications, Cambridge, UK: Cambridge University Press, 1996.