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Campbell Scientific Open Path Eddy Covariance (OPEC) User Manual

Page 42

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Appendix A. CSAT3 Orientation

Declination angles are always subtracted from the compass reading to find
True North. A declination angle East of True North is reported as positive a
value and is subtracted from 360 (0) degrees to find True North as shown
FIGURE A-2. A declination angle West of True North is reported as a negative
value and is also subtracted from 0 (360) degrees to find True North as shown
in FIGURE A-3. Note that when a negative number is subtracted from a
positive number, the resulting arithmetic operation is addition.

For example, the declination for Longmont, CO (10 June 2006) is 9.67

°, thus

True North is 360

° - 9.67°, or 350.33° as read on a compass. Likewise, the

declination for Mc Henry, IL (10 June 2006) is -2.68

°, and True North is

0

° - (-2.68°), or 2.68° as read on a compass.

FIGURE A-2. A declination angle East of True North (positive) is

subtracted from 360 (0) degrees to find True North

FIGURE A-3. A declination angle West of True North (negative) is

subtracted from 0 (360) degrees to find True North

A-2