Campbell Scientific ET107 Evapotranspiration Monitoring Station - Manual (Page 18)

ET107 Weather Station
FIGURE 1-7. Declination angles east of True North are subtracted from
0 to get True North
FIGURE 1-8. Declination angles west of True North are added to 0 to
get True North
1.5.1 Web Calculator
The web calculator provides an easy way of determining magnetic declination
of a specific site. Since magnetic declination fluctuates with time, it should be
determined each time the wind sensor orientation is adjusted. The calculator
can be accessed at:
www.ngdc.noaa.gov/geomag-web
Below is an example for Logan, UT.
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