# AO4ELT5 Proceedings

## Coherence time and turbulence velocity at the Roque de los Muchachos Observatory from G-SCIDAR turbulence profiles and operational radiosounding wind speed.

Castro-Almazan, Julio (Instituto de Astrofisica de Canarias and Dept. Astrofisica. Universidad de La Laguna), Garcia-Lorenzo, Begoña (Instituto de Astrofisica de Canarias and Dept. Astrofisica. Universidad de La Laguna), Muñoz-Tuñon, Casiana (Instituto de Astrofisica de Canarias and Dept. Astrofisica. Universidad de La Laguna)

The coherence time ($\tau_0$) is one of the relevant atmospheric optical parameters for the design of AO systems. It is directly related with the band width and the stability requirements. A proper retrieval of $\tau_0$ involves the combination of vertical turbulence and wind profiles. In this work we have used 140 nights of G-SCIDAR $C_n^2(h)$ turbulence profiles obtained at the Roque de los Muchachos Observatory (ORM) and wind profiles from simultaneous operational radiosounding balloons launched from the neighbour island of Tenerife ($\sim155$ km distant) at midnight. The wind data have been weighted to retrieve the average velocity of the turbulence ($V_0$) for each night. Here we are presenting the statistical results of $\tau_0$ and $V_0$ for the ORM and median monthly vertical profiles of wind speed for the Canary Islands. The median $\tau_0$ is 4.9 ms, with quartiles P25=2.9 ms and P75=6.5 ms. The same results for $V_0$ are 6.2, 9.5 and 12.4 m/s for P25, P50 and P75, respectively. The average wind profile shows a maximum driven by the Tropopause at an altitude ranging from 10 to 12 km over the Observatory.

DOI: 10.26698/AO4ELT5.0106- Proceeding PDF