The temporal behavior of atmospheric turbulence has been analyzed by means of angle-of-arrival (AA) fluctuation measurements. The temporal evolution of the main atmospheric optical parameters (AOP) have been studied in order to determine their stability. This is of interest because these AOP are necessary for the optimization of high angular resolution techniques. A new method of coherence time τ0 monitoring with the Generalized Seeing Monitor (GSM) is presented and the measurements obtained at major sites over the world are presented (La Silla, Cerro Pachon, Paranal, San Pedro Mártir, Mt Palomar, Mauna Kea, La Palma, Oukaïmeden, Maydanak).

Aims. Within the framework of site qualification for the future European large telescope E-ELT, a campaign of measurements was carried out for ten nights in December 2007 at Paranal using six independent instruments. Methods. To characterize the optical turbulence, two techniques were used: the statistical analysis of the fluctuations of the angle of arrival and the scintillation of the observed objects which are, in this case, a single star for DIMM, GSM, and MASS, a double star for Cute-SCIDAR, and Moon limb for MOSP and LuSci. Results. The optical parameters measured in this campaign and presented here are the seeing, the isoplanatic angle, the coherence time, and the outer scale. We obtain a good agreement with the value measured in previous campaigns. We also extracted the vertical profile of the turbulence given by C 2 n (h), and the profiles of the outer scale for the first time at Paranal. A comparison of the different results that we present here allows the determination of the energy distribution in the free atmosphere, on the ground layer as well as in the first meters above ground. This reveals a significant contribution of the surface layer to the degradation of the global seeing.

Abstract. The outer scale profile is a key parameter for the specification and optimization of the Adaptive Optics systems for the Extremely Large Telescopes. A new instrument MOSP for L 0 (h) extraction has been developed and several campaigns have been carried out at Mauna Kea, Paranal and now at Dome C in Antarctica. The MOSP instrument and results obtained during his observation campaigns are presented and discussed.