wmm

The World Magnetic Model (WMM)

The purpose of this package is to make accessible the magnetic field vector components from WMM. The supported date ranges for wmm run from 2000-01-01 to 2020-01-01. The magnetic field calculations across this time range agree with the official WMM test values to the precision provided by the authors. I will update this package for each new WMM version. For those that prefer a non-R solution, the authors of WMM provide free software to calculate magnetic field, which can be found here.

Installation

install.packages('wmm')

Usage

In v1.0.0, the only exported function is GetMagneticFieldWMM, which returns the orthogonal vector components of the main magnetic field (in nT) and secular variation field (in nT/yr) as predicted by WMM.

Example usage:

1. Calculate expected magnetic field components at a benchmark location, mid 2017. Using the default value for WMM version, this will use the more recent, "out of cycle" coefficients from WMM2015v2 as opposed to the older WMM2015 version.

GetMagneticFieldWMM(
  lon = 240,
  lat = -80,
  height = 1e5,
  time = 2017.5
)
# $x
# [1] 5674.898
# 
# $y
# [1] 14793.08
# 
# $z
# [1] -50179.48
# 
# $xDot
# [1] 25.0788
# 
# $yDot
# [1] 1.523768
# 
# $zDot
# [1] 82.51838

2. Repeat the last calculation but use the older coefficients from WMM2015 that were replaced by WMM2015v2.

GetMagneticFieldWMM(
  lon = 240,
  lat = -80,
  height = 1e5,
  time = 2017.5,
  wmmVersion = 'WMM2015'
)
# $x
# [1] 5683.518
# 
# $y
# [1] 14808.85
# 
# $z
# [1] -50163.01
# 
# $xDot
# [1] 28.16496
# 
# $yDot
# [1] 6.941152
# 
# $zDot
# [1] 86.24356

Citations

1. Chulliat, A., W. Brown, P. Alken, S. Macmillan, M. Nair, C. Beggan, A. Woods, B. Hamilton, B. Meyer and R. Redmon, 2019, Out-of-Cycle Update of the US/UK World Magnetic Model for 2015-2020: Technical Note, National Centers for Environmental Information, NOAA. doi: 10.25921/xhr3-0t19

2. Chulliat, A., S. Macmillan, P. Alken, C. Beggan, M. Nair, B. Hamilton, A. Woods, V. Ridley, S. Maus and A. Thomson, 2015, The US/UK World Magnetic Model for 2015-2020: Technical Report, National Geophysical Data Center, NOAA. doi: 10.7289/V5TB14V7

3. Maus, S., S. Macmillan, S. McLean, B. Hamilton, A. Thomson, M. Nair, and C. Rollins, 2010, The US/UK World Magnetic Model for 2010-2015, NOAA Technical Report NESDIS/NGDC.

4. McLean, S., S. Macmillan, S. Maus, V. Lesur, A. Thomson, and D. Dater, December 2004, The US/UK World Magnetic Model for 2005-2010, NOAA Technical Report NESDIS/NGDC-1.

5. Macmillian, S. and J. M. Quinn, 2000. “The Derivation of the World Magnetic Model 2000,” British Geological Survey Technical Report WM/00/17R.