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Calculate Expected Magnetic Field from WMM

Source: R/functions_wmm.R
GetMagneticFieldWMM.Rd

Function that takes in geodetic GPS location and annualized time, and returns the expected magnetic field from WMM.

Usage

GetMagneticFieldWMM(lon, lat, height, time, wmmVersion = "derived")

wmm(lon, lat, height, time, wmmVersion = "derived")

Arguments

lon

GPS longitude

lat

GPS latitude, geodetic

height

GPS height in meters above ellipsoid

time

Annualized date time. E.g., 2015-02-01 = (2015 + 32/365) = 2015.088; optionally an object (length 1) of class 'POSIXt' or 'Date'

wmmVersion

String representing WMM version to use. Must be consistent with time and one of the following: 'derived', 'WMM2000', 'WMM2005', 'WMM2010', 'WMM2015', 'WMM2015v2', 'WMM2020'. Default 'derived' value will infer the latest WMM version consistent with time.

Value

list of calculated main field and secular variation vector components in nT and nT/yr, resp. The magnetic element intensities (i.e., horizontal and total intensities, h & f) are in nT and the magnetic element angles (i.e., inclination and declination, i & d) are in degrees, with their secular variation in nT/yr and deg/yr, resp.: x, y, z, xDot, yDot, zDot, h, f, i, d, hDot, fDot, iDot, dDot

Examples

GetMagneticFieldWMM(
   lon = 240,
   lat = -80,
   height = 1e5,
   time = 2022.5,
   wmmVersion = 'WMM2020'
)
#> $x
#> [1] 5814.966
#> 
#> $y
#> [1] 14802.97
#> 
#> $z
#> [1] -49755.31
#> 
#> $xDot
#> [1] 28.0382
#> 
#> $yDot
#> [1] 1.397062
#> 
#> $zDot
#> [1] 85.63095
#> 
#> $h
#> [1] 15904.14
#> 
#> $f
#> [1] 52235.36
#> 
#> $i
#> [1] -72.27367
#> 
#> $d
#> [1] 68.55389
#> 
#> $hDot
#> [1] 11.55182
#> 
#> $fDot
#> [1] -78.04815
#> 
#> $iDot
#> [1] 0.04066726
#> 
#> $dDot
#> [1] -0.09217566
#> 

## Expected output
# x = 5814.9658886215 nT
# y = 14802.9663839328 nT
# z = -49755.3119939183 nT
# xDot = 28.0381961827 nT/yr
# yDot = 1.3970624624 nT/yr
# zDot = 85.6309533031 nT/yr
# h = 15904.1391483373 nT
# f = 52235.3588449608 nT
# i = -72.27367 deg
# d = 68.55389 deg
# hDot = 11.5518244235 nT/yr
# fDot = -78.0481471753 nT/yr
# iDot = 0.04066726 deg/yr
# dDot = -0.09217566 deg/yr

## Calculated output
#$x
#[1] 5814.966

#$y
#[1] 14802.97

#$z
#[1] -49755.31

#$xDot
#[1] 28.0382

#$yDot
#[1] 1.397062

#$zDot
#[1] 85.63095

#$h
#[1] 15904.14

#$f
#[1] 52235.36

#$i
#[1] -72.27367

#$d
#[1] 68.55389

#$hDot
#[1] 11.55182

#$fDot
#[1] -78.04815

#$iDot
#[1] 0.04066726

#$dDot
#[1] -0.09217566