Appendix A. Determining True
North and wind sensor
orientation
The orientation of the WindSonic “North Arrow Markers” is found by reading a magnetic
compass and applying the site-specific correction for magnetic declination; where the magnetic
declination is the number of degrees between True North and Magnetic North. Magnetic
declination for a specific site can be obtained from a USGS map, local airport, or through a
NOAA web calculator (
Online magnetic declination calculator
(p. 78)). A general map showing
magnetic declination for the Conterminous United States is shown in
FIGURE A-1. Magnetic declination for the conterminous United States (2015)
Declination angles east of True North are considered negative, and are subtracted from 360
degrees to get True North as shown
(p. 77) (0° and 360° are the same point on a
compass). Declination angles west of True North are considered positive, and are added to 0
degrees to get True North as shown in
Appendix A. Determining True North and wind sensor orientation
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