Wave-like Events detected from Microbarometers Measurements during BLLAST campaign

Three high precision microbarometers PAROSCIENTIFIC (Model 6000-16b) were deployed forming a triangle during the Boundary Layer Late Afternoon and Sunset Turbulence (BLLAST) campaign, which took place from 14 June to 8 July 2011 in Lannemezan (France). The objective of these instruments was to detect small scale pressure fluctuations produced in the planetary boundary layer (PBL) as well as higher mesoscale structures. Some of these wave-like structures have been deeply analyzed and their wave parameters (wavelength, phase speed, direction of propagation) have been calculated from wavelet analysis. The possible sources of these waves have been studied, being the nearly Pyrenees Mountains, convective storms, Kelvin-Helmholtz instabilities and local effects some of the possible origins.

In some cases, fluctuations in other parameters as temperature have been observed and they have been related to these wave-like fluctuations in pressure. In other cases (storm events), the fluctuations are of the order of 0.4-0.5 hPa during short time periods, being values of remarkable importance and one order of magnitude larger than the usual events found in the Stable Nocturnal Boundary Layer.