A study of Cn2 surface layer lapse rate

While it is widely assumed that turbulence strength, Cn², drops with height following -4/3 power law during the day and -2/3 at night, data does not always support this assumption. We consider the scaling of turbulence strength as a function of height above ground level based on data from multi-level ultrasonic anemometer towers and a DELTA turbulence profiler along a slant path. Using data from different height anemometers and a slant path DELTA system, we solve for the scaling parameter assuming a power law change in turbulence strength with altitude. Point measurements from the anemometers generated different lapse rate parameters than those from the path average turbulence profiler. Measured results indicate that the lapse rate power law parameter tends to change as a function of altitude and turbulence strength generally decreases more slowly with altitude near the ground than simple models assume.