Climatologia das ondas no estado de Aalagoas: uma aplicação do modelo Swan (1979-2009)

Abstract

The complex process of transforming waves generated in the offshore and propagating to the coastal zone has an impact on sediment transport, and in turn affects the coastal morphology. Despite the importance of understanding the wave climatology for, principally, coastal development projects, the high cost and maintenance of equipment to measure wave parameters are the main factors responsible for the nonexistence of wave data in many regions and subsequent understanding of the processes associated to wave forcings. In that sense, the numerical modeling of waves, combined with satellite observations are important tools to assist in the knowledge of this important environmental variable. In Alagoas state, knowledge of wave patterns in regions along the coast is scarce or almost non-existent. Thus, aiming to fill this gap the SWAN numerical model coupled with wave data measured by satellites were used to analyze the short and long term variations of the wave climate across the Alagoas state coastal region. The period of simulation and data acquired encompasses the last three decades (1979-2009). The model was used to provide a description of the global, seasonal and trends based on the wave climate analysis on the coast of Alagoas. The calculations were performed at each point of the model grid, in order to present the spatial variability of the wave conditions. The results showed that the model has a relatively good performance when compared to the satellite data. The wave trends analysis indicates that the most energetic área is located in the most distant regions off the coast, for winter (JJA) and spring (SON) months. The climatic wave energy pattern indicated more energetic waves during winter, followed by spring, and a further reduction in autumn and summer. The spatial variation in the height of the waves (Hm0) confirms that the most energetic area is in the north compared to the total area. The average height (Hm0) shows a maximum positive trend of approximately 0.4% / year for the entire study period.