The BLLAST field experiment: boundary-layer late afternoon and sunset turbulence

Abstract

Due to the major role of the sun in heating the earth’s surface, the atmospheric planetary boundary layer over land is inherently marked by a diurnal cycle. The after-noon transition, the period of the day that connects the day-time dry convective boundary layer to the night-time stable boundary layer, still has a number of unanswered scientific questions. This phase of the diurnal cycle is challenging from both modelling and observational perspectives: it is transitory, most of the forcings are small or null and the turbulence regime changes from fully convective, close to homogeneous and isotropic, toward a more heterogeneous and intermittent state