Fluxos de massa e energia sobre uma floresta pristina na Amazônia Oriental durante evento de enos.

Abstract

The understanding of the balance of mass and energy on the Earth's surface is necessary for understanding the physical, biophysical, biological and climatic processes, in the various spatial and temporal scales, and their external influences. The study was carried out aiming to characterize the behavior of in a pristine forest, as well as the closing of the energy balance, the factors that control evapotranspiration and the characterization of wind flow during a high intensity El Niño South Oscillation event (2015- 2016) in the eastern Amazon, in the Caxiuanã National Forest, state of Pará. Under the hypothesis that the inclusion of the energy storage component would increase the degree of closure of this balance, the biotic controls on evapotranspiration would be stronger and that the intensity and wind direction would be changed during the years included. The site has an aluminum micrometeorological tower composed of rapid response sensors (flow system and sonic anemometer) located 400 km from the capital Belém of Pará, using a database during the years 2015 and 2015 (from January to December). Even under conditions of El Niño-Oscilation Sul - ENOS of strong intensity little seen before, the ecosystem managed to remain within the metabolic normalities of space and time, showing the role of forest ecosystems in climate regulation at local and regional level. Most of the energy absorbed by the surface was released in the form of latent heat, especially in the dry period when the vegetation works like a real water pump for the atmosphere, a behavioral pattern for sites similar to this study. It is suggested to build a model that allows comparing and evaluating, with more consistency, the closing of the energy balance. Evapotranspiration was predominantly controlled by the physiological factors of the vegetation, especially the stomata, except for the dry period in 2015. Knowing that the structure of the vegetation can influence the metrics evaluated, for example, the conductance of the surface, more specifically the layer of the canopy, studies on the floristic composition of the vegetation are suggested, as well as the leaf characterization of the predominant species at the study site, in view of the difference that exists between the species in relation to their stomatal distribution, whether hypo, epi or anisoestomatic. The predominant wind direction was NE and L during the years evaluated. The intensity of the winds did not show statistical difference when compared by seasonality and between years, presenting few variations in relation to the direction. Knowing the flow structure above plant formations, especially forest ones, which are complex by the way, is necessary for a better understanding of the impacts that forests cause in the wind field. The results obtained here are of great interest in improving the parameterization of the exchange processes between the surface and the atmosphere, having great application in the flow studies above forest ormations in the tropical region, leading to the elaboration of better weather forecasts, with applications in weather forecasting, environmental degradation, pollution, agriculture and health.