Análise espacial e temporal do vento no estado de Alagoas

Abstract

The objective of this work is to characterize the patterns of wind in the state of Alagoas, assessing whether conditions are favorable for electricity generation through aerogenerators, and relate these patterns with local parameters, observing the behavior of atmospheric stability through different methods. We sought for determine the seasonal pattern of wind speed and direction, air temperature, intensity of turbulence and squall factor of three distinct regions of the state: Sertão, Agreste and Litoral, and evaluate the behavior of atmospheric stability in its annual cycle through the calculation of stability parameters. Daily, monthly and annual means cycles of meteorological variables that could possibly describe the wind pattern in the state of Alagoas were examined. The founded patterns were rather different among the three regions, and the most satisfactory wind behavior for wind power production was found in the Agreste region (Girau do Ponciano). The Sertão region (Água Branca), demonstrated an influence of an usual annual Brazilian Northeast wind system known as Aracati. The Aracati leads the wind speeds to reach its maximum values during the night period, what is found to be an unusual behavior. There were positive associations between air temperature peaks and wind speed in many seasons, and positive associations among the prevalence between NE and SE (interval where the sea breeze effect is predominant) and the maximum values of wind speed, indicating a possible wind intensification due to the sea breeze. It was found a decrease of the wind speed in land breeze occurrences, indicating that the southern trade winds tend to reduce the wind speed in the coastal region, and sometimes bringing land breezes occurrences to vanish. The wind speed patterns were higher in stations placed inland(Girau Ponciano, Palmeira dos Índios and Água Branca) than the coastal stations (Feliz Deserto, Roteiro e Maragogi), possibly because the inland stations are placed in higher altitudes. The atmospheric turbulence recorded in the six stations showed relatively lower values than those found in the literature, which is a good indicator for wind power usage . The atmospheric stability in Feliz Deserto was greater during the summer, decreasing with the winter approaching, and the stability estimation by the Richardson number and Brunt-Vaisala frequency methods were quite consistent, showing a maximum variation of 5% between them.