Abstract
A 140-m micrometeorological tower has been operating since August 2016 at 4 km from the coastline and 250 m from a thermal power plant that releases heat from its 20-m stacks in southeastern Brazil. The measurements include 11 levels of turbulence observations and 10 levels of slow-response temperature and humidity. The observed atmospheric structure is largely dependent on the wind direction with respect to the power plant. When winds blow from the plant to the tower, the air layer between 20 and 60 m of the atmosphere may be warmed by as much as 2°C. In these circumstances there are events when the emissions pass directly by the tower. They allow the analysis of turbulence structures of thermal plumes generated from the plant’s heat release in comparison with those generated by the surface heating. In the more common case of winds blowing from the tower to the plant, the observations allow a detailed description of the local atmospheric boundary layer. During the day, vertical profiles of turbulent quantities and their spectral distributions show a cycle controlled by interactions between the land and oceanic surfaces, such as a thermal internal boundary layer. At night, there is a systematic tendency of progressive stabilization throughout the period, suitable for the analysis of the boundary layer transition from weakly to very stable conditions. The data also grant the inference of detailed vertical profiles of turbulent diffusion coefficients directly from observations.
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