igrfmagm

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

Description

example

[XYZ,H,D,I,F,DXDYDZ,DH,DD,DI,DF] = igrfmagm(height,latitude,longitude,decimalYear) calculates the Earth magnetic field and the secular variation at a specific location and time using the International Geomagnetic Reference Field generation 13 (IGRF-13).

[XYZ,H,D,I,F,DXDYDZ,DH,DD,DI,DF] = igrfmagm(height,latitude,longitude,decimalYear,generation) optionally uses different generations of the International Geomagnetic Reference Field (IGRF-13, IGRF-12, and IGRF-11).

Examples

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Calculate the magnetic model 1000 meters over Natick, Massachusetts on July 4, 2015 using IGRF-13.

[XYZ,H,D,I,F] ...
= igrfmagm(1000,42.283,-71.35,decyear(2015,7,4),13)
XYZ =
1.0e+04 *

1.9471   -0.5086    4.8177

H =
2.0124e+04

D =
-14.6381

I =
67.3295

F =
5.2212e+04

Calculate the magnetic model at 0 and 10000 km over Lawrence, Kansas on May 15, 2018 using IGRF-13.

h = [0,10000000]
lat = [38.957114,38.957114]
lon = [-95.253997,-95.253997]
dyear = [decyear(2018,5,14), decyear(2018,5,14)]
[XYZ,H,D,I,F] = igrfmagm(h,lat,lon,dyear,13)
h =
0    10000000

lat =
38.9571   38.9571

lon =
-95.2540  -95.2540

dyear =
1.0e+03 *
2.0184    2.0184

XYZ =
1.0e+04 *

2.0655    0.0783    4.7990
0.1192    0.0046    0.2571

H =
1.0e+04 *

2.0670
0.1193

D =
2.1714
2.1968

I =
66.6981
65.1016

F =
1.0e+04 *

5.2252
0.2834

Input Arguments

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

Data Types: double

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

This function accepts latitude values greater than 90 and less than -90.

Data Types: double

Geodetic longitude specified as a matrix, scalar, or vector, in degrees. East longitude is positive and west longitude is negative. This function accepts ranges greater than 180 and less than -180.

Data Types: double

Year, in decimal format, specified as a matrix. This value can have any fraction of the year that has already passed.

Data Types: double

Generation version of the International Geomagnetic Reference Field, specified as 13, 12, or 11.

Data Types: single | double | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64 | char | string

Output Arguments

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Magnetic field vector, in nanotesla (nT), returned as a vector or matrix the same size as the input matrix with an additional dimension, the last dimension. The last dimension of the matrix is of size 3, specifying the X, Y, and Z components of the magnetic field. Z is the vertical component (+ve down). The components of this vector are in the north-east-down (NED) reference frame.

Data Types: double

Horizontal intensity, returned as a scalar, vector, or matrix, in nanotesla (nT), the same size as the input matrix.

Data Types: double

Declination, returned as a scalar, in degrees (+ve east), the same size as the input matrix.

Data Types: double

Inclination, returned as a scalar, in degrees (+ve down), the same size as the input matrix.

Data Types: double

Total intensity, returned as a scalar, in nanotesla (nT), the same size as the input matrix.

Data Types: double

Secular variation in magnetic field vector, returned as a vector or matrix, in nT/year, the same size ans the input matrix with an additional dimension, the last dimension. The last dimension of the matrix is of size 3, specifying the X, Y, and Z components of the magnetic field. Z is the vertical component (+ve down).

Data Types: double

Secular variation in horizontal intensity, in nT/year, returned as a scalar, the same size as the input matrix.

Data Types: double

Secular variation in declination, in minutes/year (+ve east), returned as a scalar, the same size as the input matrix.

Data Types: double

Secular variation in inclination, in minutes/year (+ve down), returned as a scalar, the same size as the input matrix.

Data Types: double

Secular variation in total intensity, in nT/year, returned as a scalar, the same size as the input matrix.

Data Types: double

Limitation

• This function is valid for these year ranges:

• IGRF-13 model — 1900 and 2025

• IGRF-12 model — 1900 and 2020

• IGRF-11 model — 1900 and 2015

• This function is valid between the heights of -1000 m and 5.6 Earth radii (35,​717,​567.​2 m).

• The height, latitude, longitude, and decimalYear arguments must all be the same size (matrix, scalar, and so forth).

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.

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

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

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