Climatologia do regime de vento em Manaus a partir de dados observados

Abstract

Due to its geographical location, Manaus is susceptible to light winds all year round. However, the occurrence of strong winds in a short space of time, known as gusts, which may or may not be associated with extreme precipitation, cause severe damage to the population, making it essential to forecast these events. With this in mind, the aim of this study was to analyze the records of gusts in Manaus, obtained from five automatic weather stations installed at different locations in the city, which make up the REMCLAM network. These data were initially subjected to quality control, developed in this study, and then analyzed in terms of spatial and temporal variability, as well as intensity. In the latter case, the percentile technique was applied to identify the threshold at which extreme gust events occur. Case studies were carried out to verify the behaviour of the variables wind direction, atmospheric pressure, relative humidity and air temperature in the moments prior to extreme events in order to identify a pattern and thus be able to help the agencies that act directly to minimize damage to the population due to natural phenomena, such as Civil Defence. With regard to the quality control of each station, a quantity of data was removed due to some kind of error and generated a new availability of data. The wind speed and gust distributions varied symmetrically and asymmetrically, with a difference in intensity between urban and rural areas. The most intense gusts on average occur mainly in the months of transition from dry to rainy season and rainy season. Their predominance varies from northeast to southeast depending on the rainy and dry seasons and transitions. Extreme gust events were identified using thresholds of 12.9 m/s and 8.1 m/s for urban and rural areas, respectively. Extreme gusts were up to 21.0 m/s (urban) and 17.6 m/s (rural), with greater frequency in January and October. These occurred predominantly between 10am and 5pm. Daily precipitation accumulations of up to 124 mm were associated with extreme gust events, which were also identified with the absence of rain at the same measurement location. In cases of very extreme gusts, air temperature and atmospheric pressure dropped up to an hour before the gust occurred. The direction varied abruptly, with no precipitation occurring on some days or even being seen starting up to 3 hours before the gust event with precipitation starting three hours before.

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