Generalized Scidar measurements at San Pedro Martir: II. Wind profiles statistics

International audienceWe present the results of monitoring the speed of optical turbulent layers in the atmosphere above San Pedro Mártir, Mexico, during 16 nights in May 2000. The data were obtained using the generalized scintillation detection and ranging technique (generalized scidar), developed at Nice University. This paper constitutes the second part of Avila et al. (2004), where the results concerning the measurements of the optical turbulence strength obtained at the same site and time were presented. The principal results of the present article are as follows. (I) The wind profiles remain stable during each night. (II) No evident correlation is found between the turbulence intensity (C ^2_N ) and the speed of the turbulent layers V . (III) The data only suggests a correlation between (C^2_N) values greater than 5 × 10 −17 m −2/3 and V values greater than 50 m s −1 ,approximately. (IV) Layers in the first 5 km and higher up than 16 km, above sea level, are similarly slow, with median speeds of 8.6 and 9.6 m s −1 . (V) Between 9 and 16 km, where the jet stream takes place in some of the nights, the median wind speed is 26.0 m s −1 , (VI) from the simultaneous measurements of C^2_N(h) and V (h), we compute the temporal coherence of the turbulence layer by layer. This is the first time that such data is published. In the hypothesis of Multi-Conjugate Adaptive Optics, our measurements show that the temporal responses of three deformable mirrors conjugated on the ground, at 6 and at 13 km, above sea level, would be 28, 25 and 15 ms respectively. (VII) The vertical variation of V dominates the vertical variation of the coherence time. (VIII) Also for the first time, we compare the wind velocity profiles obtained from three different techniques: generalized scidar, NCEP/NCAR (National Center for Enviromental Prediction/National Center for Atmospheric Research) Reanalysis data, and instrumented balloons. The comparison shows excellent agreement both in the modulus and the direction of the wind velocity