Analysis of the different regimes of atmospheric turbulence observed during a single night

Abstract

This work presents a comprehensive study of the different turbulence regimes observed during a night (27-28 June 2006) at the CIBA (Research Centre for the Lower Atmosphere), located in the northern part of the Iberian Peninsula, in the Duero valley, over relatively flat and homogeneous terrain. The synoptic situation was dominated by an Atlantic anticyclone, with a weak northern flow over the área of interest. Nevertheless, the actual meteorological evolution was mainly driven by the mesoscale conditions. The meteorological sequence of events were the irruption of a drainage flow, part of a nocturnal circulation established over the whole basin, and finally, the onset of a thick and dense fog layer that covered the region during several hours. These facts produced sudden changes both in the turbulence regime and in the stability of the lowest layers of the atmosphere, so that, three periods, with moderately stable, weakly stable and neutral stratification can be perfectly distinguished. The study includes the analysis of different observational datasets, gathered during the SABLES-2006 field campaign, especially designed to improve the knowledge on the nocturnal boundary layer.