2017, Presentazione, POR
Gervásio Annes Degrazia, Umberto Rizza, Silvana Maldaner, Michel Baptistella Stefanello, Débora Regina Roberti, Luís Gustavo Nogueira Martins, Vagner Anabor, Franciano Scremin Puhales, Everson Dal Piva, Otavio Acevedo, Hans Zimermann e Claudio Alberto Teichrieb
The Pampa-2016 experimental campaign have been performed in a typical Pampa lowland South American region, it consisted in both surface flux measurements (at 3 and 29 meters) and radiosonde launched every three hours. The resulting meteorological observations allowed the analysis of turbulent properties associated with both stable and convective boundary layer. The combined analysis of the surface data and vertical soundings have revealed some general characteristics of the atmospheric boundary layer for both the nocturnal stable conditions and the daytime convective environment. The continuous surface measurements, have shown that the Nocturnal Stable Inversion, occurring in calm wind situation, is generated basically by the radiative cooling mechanism that sets up after the late afternoon transition. The analysis of night-time surface data has showed also that under stable conditions in the case of vanishing wind speed, the friction velocity has unrealistic values that are very close to zero. This is an unwanted situation for numerical models that generally use this quantity as a lower boundary condition. The analysis of night-time temperature profiles has revealed two contrasting patterns in agreement with the classical classification of radiative night (very stable Boundary Layer) and a turbulent night (weakly stable Boundary layer). On the other side, the analysis of the daytime temperature profiles provided the estimation of the convective time scale, that is of the order of 10 minutes in agreement with experimental values. A spectral analysis and the consequent estimation of the spectral peaks under unstable and stable conditions are in agreement with literature values.