Estimation of turbulence energy dissipation rate and vertical eddy diffusivity with the MU radar RASS

We have conducted RASS (Radio Acoustic Sounding System) observations with the MU (Middle and Upper atmosphere) radar on 28–31 July 1994 at Shigaraki, Japan (34°51′ N, 136°06′ E) and determined the characteristics of turbulence energy dissipation rate (ε) and vertical eddy diffusivity (K) in the troposphere and lower stratosphere. We have first examined the accuracy of the Brunt Väisälä frequency squared (N²) derived from RASS temperature profiles. Then, ε and K are determined by using N² and the Doppler spectral width of turbulence echoes (σ²_turb). We found that the structures of ε and K are sometimes affected by the local variations of N². We found that sometimes ε became small, even though σ²_turb was large, because N² was small. On the contrary, K was enhanced due to small N², although σ²_turb was small.