A characterization of the optical turbulence vertical distribution ( C _ { N } ^ { 2 } profiles ) and all the main integrated astroclimatic parameters derived from the C _ { N } ^ { 2 } and the wind speed profiles above the site of the Large Binocular Telescope ( Mt .
Graham , Arizona , US ) is presented .
The statistic includes measurements related to 43 nights done with a Generalized Scidar ( GS ) used in standard configuration with a vertical resolution \Delta H \sim 1 km on the whole 20 km and with the new technique ( HVR-GS ) in the first kilometer .
The latter achieves a resolution \Delta H \sim 20-30 m in this region of the atmosphere .
Measurements done in different periods of the year permit us to provide a seasonal variation analysis of the C _ { N } ^ { 2 } .
A discretized distribution of C _ { N } ^ { 2 } useful for the Ground Layer Adaptive Optics ( GLAO ) simulations is provided and a specific analysis for the LBT Laser Guide Star system ARGOS ( running in GLAO configuration ) case is done including the calculation of the ’ gray zones ’ for J , H and K bands .
Mt .
Graham confirms to be an excellent site with median values of the seeing without dome contribution \varepsilon = 0.72 ” , the isoplanatic angle \theta _ { 0 } = 2.5 ” and the wavefront coherence time \tau _ { 0 } = 4.8 msec .
We find that the optical turbulence vertical distribution decreases in a much sharper way than what has been believed so far in proximity of the ground above astronomical sites .
We find that 50 \% of the whole turbulence develops in the first 80 \pm 15 m from the ground .
We finally prove that the error in the normalization of the scintillation that has been recently put in evidence in the principle of the GS technique , affects these measurements with an absolutely negligible quantity ( 0.04 ” ) .