Campbell Scientific CR800 and CR850 Measurement and Control Systems - Manual (Page 192)

Section 7. Installation
192
Figure 58: Mean wind-vector graph
where for polar sensors:
or, in the case of orthogonal sensors:
Resultant mean wind direction, Θu:
Standard deviation of wind direction, σ (Θu), using Campbell Scientific
algorithm:
The algorithm for σ (Θu) is developed by noting (FIGURE. Standard Deviation of
Direction
(p. 193)
) that
where