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International Geomagnetic Reference Field 11

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

Library

Environment/Gravity

Description

The International Geomagnetic Reference Field 11 block calculates the Earth's magnetic field and secular variation using the 11th generation of the International Geomagnetic Reference Field. It calculates these values at a location and time that you define.

Dialog Box

Units

Specifies the parameter and output units:

Units

Height

Metric (MKS)

Meters

English

Feet

Input decimal year

When selected, the decimal year is an input for the International Geomagnetic Reference Field 11 block. Otherwise, specify a date using the dialog parameters Month, Day, and Year.

Month

Specifies the month to calculate decimal year.

Day

Specifies the day to calculate decimal year.

Year

Specifies the year to calculate decimal year. In the list, select from 1900 to 2015.

Action for out of range input

Specifies whether out-of-range input invokes a warning, error, or no action.

Output secular variance

Select this check box to enable the output of secular variances (annual rate of change) with nonsecular variances:

Secular VarianceDescription

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

Inputs and Outputs

InputDimension TypeDescription

First

Scalar

Contains the height, in selected units.

Second

Scalar

Contains the latitude, in degrees.

Third

Scalar

Contains the longitude, in degrees.

Fourth (Optional)

Scalar

Contains the 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.

The following code illustrates how to calculate the decimal year, dyear, for March 21, 2005:

%%%BEGIN CODE%%%
dyear=decyear('21-March-2005','dd-mmm-yyyy')
%%%END CODE%%%

OutputDimension TypeDescription

First

 

Contains the magnetic field vector, in selected units.

Second

 

Contains the horizontal intensity, in selected units.

Third

 

Contains the declination, in degrees.

Fourth

 

Contains the inclination, in degrees.

Fifth

 

Contains the total intensity, in selected units.

Sixth (Optional)

 

Contains the secular variation of magnetic field vector, in selected units per years.

Seventh (Optional)

 

Contains the secular variation of horizontal intensity, in selected units per year.

Eight (Optional)

 

Contains the secular variation of declination, in minutes per year.

Ninth (Optional)

 

Contains the secular variation of inclination, in minutes per year.

Tenth (Optional)

 

Contains the secular variation of total intensity, in selected units per year.

Limitations

This block is valid between the heights of -1000 m and 600000 m.

This block is valid between the years of 1900 and 2015.

The following site has additional limitations:

http://www.ngdc.noaa.gov/IAGA/vmod/igrfhw.html

References

International Association of Geomagnetism and Aeronomy. 11th Generation International Geomagnetic Reference Field: http://www.ngdc.noaa.gov/IAGA/vmod/igrf.html

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

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