igrfmagm

Calculate Earth magnetic field and secular variation using International Geomagnetic Reference Field

Syntax

[magFieldVector,horIntensity,declination,inclination,totalIntensity,magFieldSecVariation,secVariationHorizontal,secVariationDeclination,secVariationInclination,secVariationTotal] = igrfmagm(height,latitude,longitude,decimalYear,generation)

Description

[magFieldVector,horIntensity,declination,inclination,totalIntensity,magFieldSecVariation,secVariationHorizontal,secVariationDeclination,secVariationInclination,secVariationTotal] = igrfmagm(height,latitude,longitude,decimalYear,generation) calculates the Earth magnetic field and the secular variation at a specific location and time using different generations of the International Geomagnetic Reference Field.

Examples

Calculate the Magnetic Model

Calculate the magnetic model 1000 meters over Natick, Massachusetts on July 4, 2015 using IGRF-12.

[mag_field_vector,hor_intensity,declinatioon,inclination,total_intensity] ...
= igrfmagm(1000,42.283,-71.35,decyear(2015,7,4),12)

mag_field_vector =

   1.0e+04 *

    1.9460   -0.5091    4.8179

hor_intensity =

   2.0115e+04

declinatioon =

  -14.6612

inclination =

   67.3387

total_intensity =

   5.2209e+04

Input Arguments

height — Distance

scalar

Distance, in meters, from the surface of the Earth, specified as a scalar.

latitude — Geodetic latitude

scalar

Geodetic latitude, in degrees, specified as a scalar. North latitude is positive, and south latitude is negative.

longitude — Geodetic longitude

scalar

Geodetic longitude, in degrees, specified as a scalar. East longitude is positive, and west longitude is negative.

decimalYear — Year

scalar

Year, in decimal format, specified as a decimal. This value is the desired year, including any fraction of the year that has already passed.

generation — Generation version of International Geomagnetic Reference Field

12 (default) | 11

Generation version of the International Geomagnetic Reference Field, specified as 11 or 12.

Output Arguments

magFieldVector — Magnetic field vector

vector

Magnetic field vector, in nanotesla (nT), returned as a vector. Z is the vertical component (+ve down).

horIntensity — Horizontal intensity

scalar

Horizontal intensity, in nanotesla (nT), returned as a scalar.

declination — Declination

scalar

Declination, in degrees (+ve east), returned as a scalar.

inclination — Inclination

scalar

Inclination, in degrees (+ve down), returned as a scalar.

totalIntensity — Total intensity

scalar

Total intensity, in nanotesla (nT), returned as a scalar.

magFieldSecVariation — Secular variation in magnetic field vector

vector

Secular variation in magnetic field vector, in nT/year, returned as a vector. Z is the vertical component (+ve down).

secVariationHorizontal — Secular variation in horizontal intensity

scalar

Secular variation in horizontal intensity, in nT/year, returned as a scalar.

secVariationDeclination — Secular variation in declination

scalar

Secular variation in declination, in minutes/year (+ve east), returned as a scalar.

secVariationInclination — Secular variation in inclination

scalar

Secular variation in inclination, in minutes/year (+ve down), returned as a scalar.

secVariationTotal — Secular variation in total intensity

scalar

Secular variation in total intensity, in nT/year, returned as a scalar.

Limitation

This function is valid between the heights of –1000 meters to 600,000 meters.

The 11th generation is valid between the years of 1900 and 2015, and 12th generation is valid between the years of 1900 and 2020.

This function has the limitations of the International Geomagnetic Reference Field (IGRF). For more information, see the IGRF website, https://www.ngdc.noaa.gov/IAGA/vmod/igrfhw.html.

References

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

[2] Lowes, F. J. “The International Geomagnetic Reference Field: A 'Health' Warning.” January, 2010. https://www.ngdc.noaa.gov/IAGA/vmod/igrfhw.html.