NRCAN Magnetic Declination Calculator

Magnetic Declination Calculation:

\[ \delta = f(latitude, longitude, elevation, date) \]

Latitude:

Longitude:

Elevation:

meters

Date:

Magnetic Declination:

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1. What is Magnetic Declination?

Magnetic declination is the angle between magnetic north (the direction the compass needle points) and true north (the direction along the Earth's surface towards the North Pole). This angle varies depending on your location and changes over time.

2. How Does the Calculator Work?

The calculator uses the NRCAN (Natural Resources Canada) magnetic declination model:

\[ \delta = f(latitude, longitude, elevation, date) \]

Where:

\( \delta \) — Magnetic declination (degrees)
\( latitude \) — Geographic latitude in decimal degrees
\( longitude \) — Geographic longitude in decimal degrees
\( elevation \) — Elevation above sea level in meters
\( date \) — Date of calculation (for secular variation)

Explanation: The NRCAN model incorporates geomagnetic field data and accounts for temporal changes in the Earth's magnetic field.

3. Importance of Magnetic Declination

Details: Accurate declination values are crucial for navigation, surveying, and any application requiring precise orientation. Ignoring declination can lead to significant navigation errors.

4. Using the Calculator

Tips: Enter coordinates in decimal degrees (e.g., 45.4215°N = 45.4215, 75.6972°W = -75.6972). Elevation should be in meters above sea level. Date affects the calculation due to secular variation.

5. Frequently Asked Questions (FAQ)

Q1: How often does magnetic declination change?
A: Declination changes slowly over time (secular variation), typically a few minutes per year, but this varies by location.

Q2: Why does elevation affect declination?
A: The magnetic field varies with altitude, though the effect is generally small for surface navigation.

Q3: How accurate is this calculator?
A: The NRCAN model provides declination values accurate to about 30 minutes of arc for most of Canada.

Q4: When should I update my declination value?
A: For precise work, update annually. For general navigation, every 5 years is typically sufficient.

Q5: Does this work worldwide?
A: This calculator uses the NRCAN model which is optimized for Canada. Other regions should use models specific to their location.