igrf13syn: This is a synthesis routine for the 13th generation IGRF as...

In chrono35/ArMag: ArMag

This is a synthesis routine for the 13th generation IGRF as agreed in December 2019 by IAGA Working Group V-MOD. It is valid 1900.0 to 2025.0 inclusive. Values for dates from 1945.0 to 2015.0 inclusive are definitive, otherwise they are non-definitive. INPUT

Description

This is a synthesis routine for the 13th generation IGRF as agreed in December 2019 by IAGA Working Group V-MOD. It is valid 1900.0 to 2025.0 inclusive. Values for dates from 1945.0 to 2015.0 inclusive are definitive, otherwise they are non-definitive. INPUT

Usage

igrf13syn(isv, date, itype, alt, colat, elong)

Arguments

isv	= 0 if main-field values are required, = 1 if secular variation values are required
date	= year A.D. Must be greater than or equal to 1900.0 and less than or equal to 2030.0. Warning message is given for dates greater than 2025.0. Must be double precision.
itype	= 1 if geodetic (spheroid); = 2 if geocentric (sphere)
alt	= height in km above sea level if itype = 1; = distance from centre of Earth in km if itype = 2 (>3485 km)
colat	= colatitude (0-180)
elong	= east-longitude (0-360)

Value

x,y,z x = north component (nT) if isv = 0, nT/year if isv = 1 y = east component (nT) if isv = 0, nT/year if isv = 1 z = vertical component (nT) if isv = 0, nT/year if isv = 1 f = total intensity (nT) if isv = 0, rubbish if isv = 1 if isv=0 I, D and f are returned else I=NA, D=NA and f=NA To get the other geomagnetic elements (D, I, H and secular variations dD, dH, dI and dF) use routines ptoc and ptocsv.

Adapted from 8th generation version to include new maximum degree for main-field models for 2000.0 and onwards and use WGS84 spheroid instead of International Astronomical Union 1966 spheroid as recommended by IAGA in July 2003. Reference radius remains as 6371.2 km - it is NOT the mean radius (= 6371.0 km) but 6371.2 km is what is used in determining the coefficients. Adaptation by Susan Macmillan, August 2003 (for 9th generation), December 2004, December 2009 & December 2014; by William Brown, December 2019, February 2020.

Coefficients at 1995.0 incorrectly rounded (rounded up instead of to even) included as these are the coefficients published in Excel spreadsheet July 2005. igrf13syn(isv=isv, date=date, itype=itype , alt=alt, colat= colat, elong=elong)

References

Thébault, E., Finlay, C.C., Beggan, C.D. et al. International Geomagnetic Reference Field: the 12th generation. Earth Planet Sp 67, 79 (2015). https://doi.org/10.1186/s40623-015-0228-9 (https://earth-planets-space.springeropen.com/articles/10.1186/s40623-015-0228-9): the 12th generation, Erwan Thébault, Christopher C Finlay, Ciarán D Beggan, Patrick Alken, Julien Aubert, Olivier Barrois, Francois Bertrand, Tatiana Bondar, Axel Boness, Laura Brocco, Elisabeth Canet, Aude Chambodut, Arnaud Chulliat, Pierdavide Coïsson, Francois Civet, Aimin Du, Alexandre Fournier, Isabelle Fratter, Nicolas Gillet, Brian Hamilton, Mohamed Hamoudi, Gauthier Hulot, Thomas Jager, Monika Korte, Weijia Kuang, Xavier Lalanne, Benoit Langlais, Jean-Michel Léger, Vincent Lesur, Frank J Lowes et al. Earth, Planets and Space 2015, 67:79 (27 May 2015)

See Also

https://www.ngdc.noaa.gov/IAGA/vmod/igrf.html

Examples

isv <- 1
date <- 2000
itype <- 1 # geodetic (spheroid) alt from the sea
alt <- 50 # in km
lat <- 45 # Nord positive
colat <- 90 - lat
elong <- 10

chrono35/ArMag documentation built on June 19, 2024, 6:38 p.m.