From http://www.ngdc.noaa.gov/geomagmodels/struts/calcDeclination
, the magnetic declinations of the sites varied from 12 11' to 12 17' east. To correct the magnetic azimuths of the sonics and props we'll use a declination value of 12.2 degrees for all sites.
To rotate the wind vectors, NIDAS uses the pointing angle of the sonic +V axis (Vazimuth), which is pointing azimuth of the sonic boom + 90, or the sonic +U axis - 90.
From logbook entries of the sonic azimuths:
site |
pointing |
sonic boom azimuth, magnetic |
boom azimuth, true (mag+12.2) |
Vazimuth, true |
|---|---|---|---|---|
playa1 |
|
|
|
|
abc2 |
east |
83.4 |
95.6 |
95.6 + 90 = 185.6 |
hiland2 |
east |
249.5 - 180 = 69.5 |
81.7 |
81.7 + 90 = 171.7 |
wvally4 |
west |
|
|
|
eslope5 |
east |
|
|
|
wslope6 |
west |
77.8 |
90.0 |
0.0 |
river7 |
west |
85.5 |
97.7 |
7.7 |
Props
site |
pointing |
prop azimuth, magnetic |
|
|---|---|---|---|
playa1 |
|
|
|
wslope6 |
south |
346.1 |