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Magnetic Declination Equation:
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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 in Earth's magnetic field.
The calculator uses the NOAA magnetic declination equation:
Where:
Explanation: The arctangent function calculates the angle whose tangent is the ratio of Y to X components of Earth's magnetic field.
Details: Accurate magnetic declination calculation is crucial for navigation, surveying, map reading, and any application requiring precise directional information. It ensures proper alignment between magnetic compass readings and true geographic directions.
Tips: Enter the Y and X components of Earth's magnetic field in nanoteslas (nT). These values can be obtained from NOAA magnetic field models or measurement instruments. The X component cannot be zero.
Q1: Why does magnetic declination vary by location?
A: Earth's magnetic field is not uniform across the planet. The magnetic poles are not aligned with the geographic poles, creating variation that changes with location.
Q2: How often does magnetic declination change?
A: Magnetic declination changes gradually over time due to shifts in Earth's magnetic field. NOAA updates magnetic models every 5 years to account for these changes.
Q3: What's the difference between declination and inclination?
A: Declination is the horizontal angle between magnetic and true north. Inclination (or dip) is the vertical angle between the magnetic field and the horizontal plane.
Q4: How accurate is this calculation?
A: The mathematical calculation is precise, but the accuracy depends on the quality of the input magnetic field component values.
Q5: Can I use this for navigation purposes?
A: For critical navigation applications, always use the most current official NOAA magnetic declination values for your specific location.