Dynamics of the Atmospheric Boundary Layer over two middle-latitude rural sites with Doppler lidar

Abstract

The Atmospheric Boundary Layer (ABL) over two middle-latitude rural sites was characterized in terms of mean horizontal wind and turbulence sources using a standard classification methodology based on Doppler lidar. The first location was an irrigated olive orchard in Úbeda (Southern Spain), representing one of the most important crops in the Mediterranean basin and a typical site with Mediterranean climate. The second location was PolWET peatland site in Rzecin (Northwestern Poland), representing one of the largest natural terrestrial carbon storages that have a strong interaction with the climate system. The results showed typical situations for non cloud-topped ABL cases, where ABL is fully developed during daytime due to convection, with high turbulent activity and strong positive skewness indicating frequent and powerful updrafts. The cloud-topped cases showed the strong influence that clouds can have on ABL development, preventing it to reach the same maximum height and introducing top-down movements as an important contribution to mixing. The statistical analysis of turbulent sources allowed for finding a common diurnal cycle for convective mixing at both sites, but nocturnal wind shear driven turbulence with marked differences in its vertical distribution. This analysis demonstrates the Doppler lidar measurements and the classification algorithm strong potential to characterize the dynamics of ABL in its full extent and with high temporal resolution. Moreover, some recommendations for future improvement of the classification algorithm were provided on the basis of the experience gained.