The temporal cross-correlation function of the angle-of-arrival (AOA) fluctuations of two optical waves propagating through atmospheric turbulence carries information regarding the average wind velocity transverse to the propagation path. We present and discuss two estimators for the retrieval of the path-averaged beam-transverse horizontal wind velocity, vt. Both methods retrieve vt from the temporal cross-correlation function of AOA fluctuations obtained from two closely spaced light-emitting diodes (LEDs). The first method relies on the time delay of the peak (TDP) of the cross-correlation function, and the second method exploits its slope at zero lag (SZL). Over a 9 h period during which vt varied between −1.3  ms−1 and 2.0  ms−1, the maximum rms difference between optically retrieved and in situ measured 10 s estimates of vt was found to be 0.18  ms−1 for the TDP estimator and 0.23  ms−1 for the SZL estimator. Applicability and limitations of these two optical wind retrieval techniques are discussed.
['Shiril Tichkule', 'Andreas Muschinski']
Optical anemometry based on the temporal cross-correlation of angle-of-arrival fluctuations obtained from spatially separated light sources