Optical Turbulence Profiles at Mauna Kea Measured by MASS and SCIDAR

The vertical distribution of turbulence over Mauna Kea has been measured on four nights in 2002 October, simultaneously using two different instruments based on stellar scintillation—the generalized SCIDAR (scintillation detection and ranging) and MASS (multiaperture scintillation sensor). The turbulence integrals match within 20%, and the low-resolution profiles delivered by MASS correctly reveal the localization of the strongest high-altitude turbulent layers. As deduced from DIMM (differential image motion monitor), MASS, and SCIDAR measurements, optical turbulence in the first 0.7 km above the summit contributed typically half of the total integral, the latter corresponding to a seeing of 0 .5. The ground layer and free atmosphere are not correlated.