igrf {igrf}

International Geomagnetic Reference Field

Description

The 13th Generation International Geomagnetic Reference Field.

Usage

igrf(field = "main", year, type = "spheroid", altitude, latitude, longitude)

Arguments

field

main field (default = "main") or secular variation ("variation") data output

year

Decimal year between 1900 and 2030 A.D

type

"spheroid" (default) or "sphere" representation

altitude

in km above the earth surface for a spheroid type, or distance from the earth center (radial distance) for the sphere representation (in the later the value should exceed 3485km)

latitude

latitude in decimal degrees

longitude

longitude in decimal degrees

Details

The R model underpinning the base function is the original Fortran model published by Alken et al. 2021 and available on the project website <https://www.ngdc.noaa.gov/IAGA/vmod/igrf.html>.

Outputs have been verified to correspond with the original code with the exception that values in the R implementation are not rounded before output (as in the original model). For all intents and purposes the data can be considered equivalent.

For full model details I refer Alken et al. 2021, and the project website where both the original code and a brief model description can be found. The authors of both the R package and the original Fortran code take no responsibility regarding the use of these data within a professional context <https://www.ngdc.noaa.gov/IAGA/vmod/igrfhw.html>.

Value

a data frame with components X,Y,Z,F, D, H and I for the main geomagnetic field or the secular variations, i.e. instantaneous time rate of change of the geomagnetic main field. Keep in mind that the secular variations are generally only used for interpolation purposes and do not reflect the actual rate of change. For more guidance on the use of the secular variations and caveats we refer to the main project's website <https://www.ngdc.noaa.gov/IAGA/vmod/igrfhw.html>.

Examples

field <- igrf::igrf(
 field = "main",
 year = 2000,
 type = "spheroid",
 altitude = 2,
 latitude = 50,
 longitude = 10
)