High altitude wind speeds have been adopted as a parameter for astronomical site selection based on the relationship found at the Paranal and Cerro Pachón sites between the average velocity of the turbulence ( V _ { 0 } ) and winds at the 200 millibar pressure level ( V _ { 200 } ) .
Although this relationship has not been checked at any other site in the world and a connection between image quality and V _ { 200 } has not been proven anywhere , high altitude wind speed ( V _ { 200 } ) is a parameter for checking the suitability of sites for adaptive optics and surveying potential sites for ELT .

We present comprehensive and reliable statistics of high altitude wind speeds and the tropospheric flows at the location of five important astronomical observatories .
We have used the National Center for Environmental Prediction ( NCEP/NCAR ) Reanalysis database to collect wind data at nine tropospheric pressure levels for the five selected sites .
For comparison and validation of the data from the climate diagnostic model , we have also obtained wind profiles from radiosonde stations .
The degrees of correlation found indicate a high level of significance between NCEP/NCAR Reanalysis and balloon databases , pointing to NCEP/NCAR Reanalysis as a useful database for site characterization .

Statistical analysis exclusively of high altitude winds point to La Palma as the most suitable site for adaptive optics , with a mean value of 22.13 m s ^ { -1 } at the 200 mbar pressure level .
La Silla is at the bottom of the ranking , with the largest average value 200 mbar wind speed ( 33.35 m s ^ { -1 } ) .
We have found a clear annual periodicity of high altitude winds for the five sites in study .

We have also explored the connection of high to low altitude atmospheric winds as a first approach of the linear relationship between the average velocity of the turbulence and high altitude winds ( Sarazin & Tokovinin 2001 ) .
We may conclude that high and low altitude winds show good linear relationships at the five selected sites .
The highest correlation coefficients correspond to Paranal and San Pedro Mártir , while La Palma and La Silla show similar high to low altitude wind connection .
Mauna Kea shows the smallest degree of correlation , which suggests a weaker linear relationship .
Our results support the idea of high altitude winds as a parameter for rank astronomical sites in terms of their suitability for adaptive optics , although we have no evidence for adopting the same linear coefficient at different sites .
The final value of this linear coefficient at a particular site could drastically change the interpretation of high altitude wind speeds as a direct parameter for site characterization .