International Geomagnetic Reference Field

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

• Library:

• Aerospace Blockset / Environment / Gravity

• 

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Description

The International Geomagnetic Reference Field block calculates the Earth magnetic field and secular variation using the selected International Geomagnetic Reference Field generation. It calculates the Earth magnetic field and secular variation at a position and time using the selected International Geomagnetic Reference Field generation.

Limitations

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

• This block is valid for these year ranges:

  • IGRF-13 model — 1900 and 2025

  • IGRF-12 model — 1900 and 2020

  • IGRF-11 model — 1900 and 2015

• If the decimal year is outside the valid range for a generation,​ the International Geomagnetic Reference Field block linearly extrapolates the magnetic field to the out-of-range decimal year.​

• For additional limitations, see :

  The International Geomagnetic Reference Field: A "Health" Warning

Ports

Input

h — Height

scalar

Height, specified as a scalar, in selected units.

Data Types: double

μ (deg) — Latitude

scalar

Latitude, specified as a scalar in degrees. This block accepts latitude values greater than 90 and less than -90.

Data Types: double

l (deg) — Longitude

scalar

Longitude, specified as a scalar, in degrees. This block accepts ranges greater than 180 and less than -180.

Data Types: double

dyear — Desired year

scalar

Desired year in a decimal format to include any fraction of the year that has already passed. The value is the current year plus the number of days that have passed in this year divided by 365. To calculate the decimal year, dyear, for March 21, 2015:

dyear=decyear('21-March-2015','dd-mmm-yyyy')

Dependencies

To enable this port, select Input decimal year.

Data Types: double

Output

XYZ — Magnetic field

vector

Magnetic field, returned as a vector, in selected units. The components of this vector are in the north-east-down (NED) reference frame.

Data Types: double

H — Horizontal intensity

scalar

Horizontal intensity, returned as a scalar, in selected units.

Data Types: double

D — Declination

scalar

Declination, returned as a scalar, in degrees.

Data Types: double

l — Inclination

scalar

Inclination, returned as a scalar, in degrees.

Data Types: double

F — Total intensity

scalar

Total intensity, returned as a scalar, in selected units.

Data Types: double

DXDYDZ — Secular variation of magnetic field

vector

Secular variation of magnetic field, returned as a vector in selected units per year.

Dependencies

To enable this port, select Output secular variation.

Data Types: double

DH — Secular variation of horizontal intensity

scalar

Secular variation of horizontal intensity, returned as a scalar, in selected units per year.

Dependencies

To enable this port, select Output secular variation.

Data Types: double

DD — Secular variation of declination

scalar

Secular variation of declination, returned as a scalar, in minutes per year.

Dependencies

To enable this port, select Output secular variation.

Data Types: double

DI — Secular variation of inclination

scalar

Secular variation of inclination, returned as a scalar, in minutes per year.

Dependencies

To enable this port, select Output secular variation.

Data Types: double

DF — Secular variation of total intensity

scalar

Secular variation of total intensity, returned as a scalar, in selected units per year.

Dependencies

To enable this port, select Output secular variation.

Data Types: double

Parameters

Generation — International Geomagnetic Reference Field generation

IGRF-13 (default) | IGRF-11 | IGRF-12

International Geomagnetic Reference Field generation, selected from IGRF-13, IGRF-12, or IGRF-11.

Programmatic Use

Block Parameter: generation

Type: character vector

Values: 'IGRF-13' | 'IGRF-11' | 'IGRF-12'

Default: 'IGRF-13'

Data Types: char | string

Units — Units

Metric (MKS) (default) | English

Parameter and output units, specified as:

Units	Height
Metric (MKS)	Meters
English	Feet

Programmatic Use

Block Parameter: units

Type: character vector

Values: 'Metric (MKS)' | 'English'

Default: 'Metric (MKS)'

Input decimal year — Desired year

on (default) | off

• To specify the decimal year with an input port for the World Magnetic Model 2015 block, select this check box.

• To specify the decimal year using the values of Month, Day, and Year, clear this check box.

Dependencies

To enable Month, Day, and Year, clear this parameter.

Programmatic Use

Block Parameter: time_in

Type: character vector

Values: 'on' | 'off'

Default: 'on'

Month — Input month

January (default) | February | March | April | May | June | July | August | September | October | November | December

Month to calculate decimal year.

Dependencies

To enable this parameter, clear Input decimal year.

Programmatic Use

Block Parameter: month

Type: character vector

Values: 'January' | 'February' | 'March' | 'April' | 'May' | 'June' | 'July' | 'August' | 'September' | 'October' | 'November' | 'December'

Default: 'January'

Day — Input day

1 (default) | 1 to 31

Day to calculate decimal year.

Dependencies

To enable this parameter, clear Input decimal year.

Programmatic Use

Block Parameter: day

Type: character vector

Values: '1' to '31'

Default: '1'

Year — Input year

2020 (default) | 1900 to 2020

Year to calculate decimal year, specified as 1900 to 2020.

Dependencies

To enable this parameter, clear Input decimal year.

Programmatic Use

Block Parameter: year

Type: character vector

Values: any year

Default: '2020'

Action for out-of-range input — Out-of-range block behavior

None (default) | Warning | Error

Out-of-range block behavior, specified as follows:

Action	Description
None	No action.
Warning	Warning in the MATLAB® Command Window, model simulation continues.
Error (default)	MATLAB returns an exception, model simulation stops.

Programmatic Use

Block Parameter: action

Type: character vector

Values: 'None' | 'Warning' | 'Error'

Default: 'Error'

Output secular variance — Secular variances

on (default) | off

Select this check box to enable the output of secular variances (annual rate of change) with nonsecular variances. Otherwise, clear this check box.

Secular Variance	Description
Magnetic Field	Magnetic field vector, in nanotesla (nT). Z is the vertical component (+ve down)
Horizontal 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)
SV Magnetic Field	Secular variation of magnetic field
SV Horizontal Intensity	Secular variation of horizontal intensity
SV Declination	Secular variation of declination, the angle between true north and the magnetic field vector (positive eastward)
SV Inclination	Secular variation of inclination, the angle between the horizontal plane and the magnetic field vector (positive downward)
SV Total Intensity	Secular variation of total intensity

Clear this check box to enable just the nonsecular variances:

• Magnetic Field

• Horizontal Intensity

• Declination

• Inclination

• Total Intensity

Programmatic Use

Block Parameter: sv_out

Type: character vector

Values: 'on' | 'off'

Default: 'on'

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.