A Study of Convection Capped by a Stable Layer Using Doppler Radar and Acoustic Echo Sounders

Abstract

Simultaneous atmospheric acoustic echo sounding and Doppler radar measurements were used to study some of the characteristics of an unstable boundary layer capped by an inversion. The resultant set of observations shows that the turbulent energy dissipation rate was constant with height up through the inversion layer. Since production from buoyancy and shear were found to be negligible in the upper part of the convective layer, the turbulent energy must be supplied by energy flux convergence. The stress at the top of the momentum layer was estimated to be approximately 2.5 dyn cm?2, assuming the energy flux divergence, term was small above the inversion. In addition, the height where the downward heat flux above the inversion went to zero and the height where the shearing stress went to zero were different. For the case analyzed in this paper, the apparent height at which the heat flux went to zero was 0.6 times the height where the shearing stress became zero.