Campbell Scientific Open Path Eddy Covariance (OPEC) - Manual (Page 15)

OPEC Open-Path Eddy-Covariance System
To enter the “sonic_azimuth” using the datalogger keyboard, press the <Esc>
key until the Campbell Scientific Inc. logo is visible in the upper left hand
corner of the display. Press the <Enter> key. Select the menu “Sonic_Azmth”
ell Scientific
To enter the “sonic_azimuth” using LoggerNet, connect to the datalogger with
enter the
press the <enter> key.
and press the <Enter> key. Enter the azimuth of the negative x-axis and press
the <Enter> key. Press the <Esc> several times so that the Campb
logo if visible.
LoggerNet and display the Public data table. Locate the variable
“sonic_azimuth” and click on it. Double click on the number field,
negative x-axis azimuth and
Don’t forget to account for the magnetic declination at the site;
see Appendix A for details.
FIGURE 3-1 and FIGURE 3-2 show the orientation of an IRGASON azimuth
bearing of 140 degrees, e.g., the negative x-axis i
s pointing into 140 degrees.
If the wind is blowing into the sonic, from the negative x-axis to the positive x-
axis (from the transducers to the block), the horizontal wind vector angle
(wind_dir_csat3) is 0 degrees (wind vector) and the compass wind direction
(wnd_dir_compass) is 140 degrees (wind vane).
North
Y
X
Wind Vane
Wind Vector
FIGURE 3-1. IRGASON right hand coordinate system, horizontal wind
vector angle is 0 degrees
NOTE
7