Investigação sobre a camada limite noturna em sítios experimentais da Amazônia: regimes de estabilidade e classes de flutuações turbulentas

Abstract

We used data measured in micrometeorological towers installed in three areas of primary forest: i) in the experimental site of Uatumã, on the Uatumã Sustainable Development Reserve ( RDSU ), in central Amazonia approximately 135 km northeast of Manaus; ii) in the Biological Reserve of Jarú ( Rebio - Jarú ), in an area of upland forest located about 100 km north of the city of Ji-Paraná, Rondônia, Western Amazon; and iii) in the Ferreira Penna Scientific Station, administered by the Goeldi Museum, located in the National Caxiuanã Forest, county of Melgaço, PA, Eastern Amazon.We sought to investigate the structure of the nocturnal atmospheric turbulence above the Amazon rainforest and its variability depending on: i) the stability regimes differentiated by the following conditions: atmospheric flow with strong winds, light winds and global intermittency, as proposed by Sun et al. (2012). For this we used statistical characteristics of turbulent quantities in the surface boundary layer in each one of the above stability regimes, in wet and dry periods; ii) Classes of evolution of the nocturnal boundary layer based on the patterns of variability of turbulent time series (wind speed, specific humidity, (q), and temperature, (T), and net radiation (Rn). Based on the oscillation characteristics of these quantities at intervals of 30 minutes, it was possible to establish classes that express variability patterns of nocturnal turbulence due to the dominant organized movement, with the presence or not of gravity waves and influence of clouds. The results indicate the presence of organized movement as “coherent structures" for almost all studied cases. However, differences were noted among the characteristics of the investigated experimental sites particularly as regards the occurrence of gravity waves. This research can be very important in understanding aspects of forest - atmosphere interaction during night - time, providing support for a better simulation of the atmospheric flow above experimental sites in Amazonia under stable conditions.