Quantitative acoustic sounding from the top of a steep mountain

Abstract

Abstract In this paper, profiles of vertical wind speed and temperature structure parameter (Ct 2) obtained by acoustic sounders at the top of a steep mountain are presented for both stable and unstable stratification. Under convective conditions, plumes similar to the ones found in flat terrain seem to be present with vertical wind speed maxima of up to 2ms-1. (Ct 2) and (σw 2) (the vertical wind component variance) exhibit a stronger dependence with height from the one observed over flat terrain. During stable night-time conditions, an elevated inversion is found and its motion in time, affected by subsidence and local flows, has been analysed. Under these conditions, the height variation is different above and below the elevated inversion usually present and the vertical wind speed is Jess than lms-1. Regardless of stability conditions though, local isotropy has been found to exist in the surface layer fed by buoyancy in the daytime and, most probably, by mechanical mixing at night.