GeophysicsLive data
Regional Magnetic Lab
Reference geomagnetic field grids for exploration.
Computes the IGRF-14 main field in your browser for any area, epoch and height, and reduces ground magnetometer readings to a residual anomaly with diurnal correction, kriged into a contour map.
Overview
The spherical-harmonic synthesis to degree 13 matches NOAA’s calculator to within 0.1 nT. A point calculator gives the declination to set on a compass for any site and date.
What you enter · What you get
What you enter
- Survey date and height
- Area and grid step, or magnetometer readings
- Base-station readings for diurnal drift
What you get
- F, H, X, Y, Z, D, I and secular variation grids
- Residual anomaly map and reduced-readings table
- Compass declination for any point
How it works in the field
Define the survey area
Fetch the reference grid
Export to Surfer
Method and equations
Main field
Scalar potential from IGRF-14 Gauss coefficients, geodetic to geocentric conversion on WGS 84.
V = a Σn (a/r)n+1 Σm (gnm cos mλ + hnm sin mλ) Pnm(cos θ)
Residual anomaly
Observed total field minus diurnal drift and the IGRF value at the same place and time.
ΔT = Tobs − δTd(t) − FIGRF(φ, λ, h, t)
Who uses it
Exploration geophysicistsMineral and petroleum explorersGeophysics students
Standards and references
- Alken, P. et al. (2021). International Geomagnetic Reference Field: the thirteenth generation. Earth, Planets and Space, 73, 49.
- IAGA Working Group V-MOD (2024). International Geomagnetic Reference Field, 14th generation. doi:10.5281/zenodo.14012302.
- Telford, W.M., Geldart, L.P. & Sheriff, R.E. (1990). Applied Geophysics, 2nd ed. Cambridge University Press.
Results support professional judgement. They do not replace a licensed engineer’s or geologist’s sign-off.
At a glance
- Category
- Geophysics
- Runs on
- Phone, tablet and desktop browser
- Export
- Surfer GRD, CSV, PNG map, PDF report
- Access
- Subscribers
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