Evidence of dynamical coupling between the residual layer and the developing convective boundary layer

The diurnal cycle of the atmospheric boundary layer (ABL) has been document ed on 8 August 1998 in the framework of the Etude et Simulation de la QUali te de l'air en Ile-de-France (ESQUIF) experiment that took place in the Par is area. The ABL structure was documented by means of a ground-based lidar, surface meteorological stations and soundings. The interaction between the residual layer and the convective boundary layer is investigated using the collected data as well as mesoscale modelling. As opposed to the generally accepted concept, we find evidence of entrainment at the top of the residu al layer. High temporal simulations of the 8 August 1998 case made with the mesoscale atmospheric model Meso-NH also show evidence of mixing at the to p of the residual layer (RL). This mixing is believed to be related to the presence of convective (gravity) waves in the RL.