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 The following are from logbook entries of the sonic azimuths:.
Note that all measured azimuths are in degrees magnetic, with the declination set to 0 on the compass or datascope, to reduce untraceable mental mistakes.
site | log date site | pointing | sonic boom azimuth (mag) , magnetic | boom azimuth (true, true (mag+12.2) | Vazimuth, true (true) boom+90) | notes | ||||
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playa1 | 12/18 | west | 76.9 + 180 = 256.9 | 269.1 | 359.1 |
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playa1 | 1/5 | " | 77.3+180 = 257.3 playa1 |
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abc2 | 12/16 | east | 83.4 | 83.4 + 12.2 = 95.6 | 95.6 + 90 = 185.6 | 249.5 - 180 = 69.5 | 81.7 | 171.7 |
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abc2 | 1/4 | " | 80 |
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| shot from the back (centered mast in claws), so hard to see; still thought it was okay | ||||
hiland3 | 12/14 | east | 249.5 - 180 = 69.5 | 81.7 | 171.7 |
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hiland3 | 12/20 | " | 253 | hiland2 | east | 249.5 - 180 = 6973.5 | 85.7 | 81 175.7 |
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hiland3 | 1/3 | " | 254.2 - 180 = 74.2 |
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| shot from across the street | ||||
wvally4 | 12/16 | west | 86 81.7 + 90 180 = 171266.7 | 278.9 | 8.9 |
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wvally4 west | 12/19 | " | 80.3 + 180 = 260.3 | 272.5 | 2.5 | mast was not lowered between 12/16 and 12/19 | ||||
wvally4 | 12/20 | " | 85.8 + 180 = 265.8 | 278.0 | 8.0 |
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wvally4 | 1/3 | " | 80.8 +180 = 260.8 |
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eslope5 | 12/15 | east | 248.7 - 180 = 68.7 | 80.9 | 170.9 |
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eslope5 | 1/5 | " | 251.1 - 180 = 71.1 |
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wslope6 | 12/13 | west | 77.8 + 180 = 257.8 | 270 | 90 0.0 0.0 |
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wslope6 | 1/6 | " | 79.3 |
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river7 | 12/13 | west | 85.5 | 97.7 | + 180 = 265.5 | 277.7 | 7.7 |
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Props
site | log date | pointing | prop azimuth, magnetic | prop az, true (mag+12.2) | notes |
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playa1 | 11/20 | north |
| 1.0 |
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playa1 | 12/18 | north | 171.7 + 180 = 351.7 | 3.9 |
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playa1 | 1/6 | " | 174.2+180=354.2 | 6.4 |
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wslope6 | 11/20 | north |
| 1.7 | should this have been -1.7, which agrees with 12/13? |
wslope6 | 12/13 | north | 346.1 | 358.3 |
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wslope6 | 1/6 | " | 169.3+180=349.3 | 1.5 | 7.7 |