Combining turbulence profiles from MASS and SLODAR: a statistical study of the evolution of the seeing at Paranal

We have recombined turbulence profiles from MASS and SLODAR at Paranal Observatory using a new grid of atmospheric layers defined on the basis of the comparison between the MASS and SLODAR weighting functions. A statistical analysis of the relation between the total Paranal DIMM Cn2, the ground layer Cn2 and the free atmosphere Cn2 is presented. Taking into account the height of the VLT Unit Telescopes we have recalculated the seeing skipping the atmosphere below that height, obtaining an estimation of the real turbulence affecting science at the Very Large Telescope and its evolution from January 2005 to June 2007.