GeoMagSharp 1.4.0

GeoMagSharp

A C# library for geomagnetic field calculations using spherical harmonic models. GeoMag # is a port of the C++ application GeoMag 7.0 distributed by NOAA.

Installation

dotnet add package GeoMagSharp

Or via the NuGet Package Manager:

Install-Package GeoMagSharp

Quick Start

using GeoMagSharp;

// Load a coefficient file
var geoMag = new GeoMag();
geoMag.LoadModel("WMM2025.COF");

// Configure calculation
var options = new CalculationOptions
{
    Latitude = 45.0,
    Longitude = -93.0,
    StartDate = new DateTime(2025, 7, 1),
    SecularVariation = true,
    CalculationMethod = Algorithm.BGS
};
options.SetElevation(0, Distance.Unit.meter, true);

// Run calculation
geoMag.MagneticCalculations(options);

// Access results
var result = geoMag.ResultsOfCalculation[0];
Console.WriteLine($"Declination: {result.Declination.Value:F2} degrees");
Console.WriteLine($"Inclination: {result.Inclination.Value:F2} degrees");
Console.WriteLine($"Total Field: {result.TotalField.Value:F1} nT");

Async API

// Async with progress reporting and cancellation
var cts = new CancellationTokenSource();
var progress = new Progress<CalculationProgressInfo>(p =>
    Console.WriteLine($"{p.PercentComplete:F0}% - {p.StatusMessage}"));

var model = await ModelReader.ReadAsync("WMM2025.COF", progress, cts.Token);
await geoMag.MagneticCalculationsAsync(options, progress, cts.Token);
await geoMag.SaveResultsAsync("output.txt", false, cts.Token);

Supported Models

Bundled coefficient files are in the coefficient/ directory. See coefficient/NOTICE.md for attribution and download links for non-bundled models.

Target Frameworks

• .NET Framework 4.8
• .NET Standard 2.0 (compatible with .NET Core 2.0+, .NET 5+)

API Overview

Core Classes

• GeoMag - Main entry point for loading models and running calculations
• ModelReader - Parses COF/DAT coefficient files into model objects
• Calculator - Low-level spherical harmonic calculation engine
• CalculationOptions - Configuration for latitude, longitude, date, elevation, etc.

Model Classes

• MagneticModelSet - A set of magnetic models (main field + secular variation)
• MagneticModelCollection - Manages multiple model sets with JSON serialization
• MagneticCalculations - Calculation results (declination, inclination, field components)

Result Properties

Each MagneticCalculations result contains MagneticValue objects with:

• Value - The calculated value
• ChangePerYear - Secular variation (when enabled)

Available components: Declination, Inclination, TotalField, HorizontalIntensity, NorthComponent, EastComponent, VerticalComponent, GridVariation.

License

MIT License - see LICENSE for details.

Bundled coefficient files are U.S. Government works in the public domain. See coefficient/NOTICE.md for full attribution.