Hi,
I recently installed an open path eddy covariance system with IRGASON, HFP01, TCAV, CS616, FW05,NR-LITE2, and CR3000 datalogger.
In FLUX data table, there is two variables of wind direction: wnd_dir_sonic and wnd_dir_compass. I don't know what is exactly the difference. (wnd_dir_sonic+wnd_dir_compas is always equal to 360°)
Thanks.
Hi Jamal,
Wind_dir_compass is the resultant wind dirction using the compass system. It will be between 0 and 360 degrees. The wind_dir_sonic is a resultant wind direction using the sonic right handed coordinate system (See page 24 in the CSAT3 manual). This wind direction will always be between 0 to 180 degree and 0 to -180 degrees. This wind direction is a good "check" on where the wind is blowing in reference to the front of the sonic transducers. wind_dir_sonic values that are between -90 to 0 and 0 to 90 degrees mean the wind is blowing into the CSAT3 sensor head. Values of -180 to -90 and 90 to 180 suggest the wind is blowing more behind transducers (-180 and 180 mean directly behind the block) so that data should be quality flagged.