1. What is Magnetic Declination?

Magnetic declination (also called magnetic variation) is the angle between magnetic north and true north. This angle varies depending on your location on Earth's surface and changes over time due to movements of Earth's magnetic field.

2. How Does the IGRF Model Work?

The calculator uses the International Geomagnetic Reference Field (IGRF) model:

The IGRF is a mathematical model of Earth's magnetic field that provides:

• Spherical harmonic coefficients representing the magnetic field
• Regular updates every 5 years
• Global coverage with high accuracy
• Temporal variations accounting for secular changes

Explanation: The IGRF model calculates magnetic field components based on location and time, from which declination is derived.

3. Importance of Magnetic Declination Calculation

Details: Accurate magnetic declination is crucial for navigation, surveying, aviation, marine navigation, and outdoor activities. It ensures proper orientation when using magnetic compasses.

4. Using the Calculator

Tips: Enter the year between 1900 and 2030. The calculator will provide the magnetic declination value based on the IGRF model for that specific year.

5. Frequently Asked Questions (FAQ)

Q1: Why does magnetic declination change over time?
A: Earth's magnetic field is dynamic and undergoes secular variation, causing declination values to change gradually over years and decades.

Q2: How accurate is the IGRF model?
A: The IGRF model typically provides accuracy within 30 minutes of arc for declination, though local anomalies may cause greater errors in specific locations.

Q3: Can I use this for any location?
A: This calculator provides general values. For precise local declination, specific coordinates are required in addition to the year.

Q4: How often is the IGRF model updated?
A: The IGRF is updated every 5 years, with the latest version extending predictions 5 years into the future from the last update.

Q5: What's the difference between declination and inclination?
A: Declination is the horizontal angle between magnetic and true north, while inclination (dip) is the vertical angle between the magnetic field and horizontal plane.