Statistics and analysis of high-altitude wind above the Canary Islands observatories

High-altitude wind has been recently proposed as an important parameter to be taken into account for astronomical site selection. We present here comprehensive and reliable statistics for wind speeds at the 200 mbar (upsilon(200) hereafter) pressure level (approximately 12 km above the Canary Islands) based on long-term climate diagnostics archive and balloon data. The results presented in this paper demonstrate the remarkably good behaviour of the high-altitude wind above the Canarian archipelago, with low mean values of upsilon(200) (22.12 m s(-1) above the Roque de los Muchachos Observatory, hereafter ORM) and provide independent confirmation of the potential of the ORM and the Teide Observatory (OT) for adaptive Optics. A comparison of upsilon(200) values from a climatological data base and in situ measurements with radiosondes launched from Santa Cruz de Tenerife reveals an excellent level of agreement, which lends support to the claim that climate diagnostic measurements provide a useful tool for astronomical site assessment, although a rigorous control of data quality, analysis and cross comparison needs to be performed before the method becomes extensively used. Moreover, the correlation of the results for La Palma and Tenerife confirms the homogeneity of the Canarian sky at the tropopause level. The analysis of frequency and variability of upsilon(200) led us to propose a seasonal periodicity of upsilon(200).