Tese
Escalas temporais do escoamento noturno dentro e acima de um dossel na Amazônia
Fecha
2015-07-17Registro en:
SANTOS, Daniel Michelon dos. Temporal scales of the nocturnal flow within and above a forest canopy in amazonia. 2015. 98 f. Tese (Doutorado em Física) - Universidade Federal de Santa Maria, Santa Maria, 2015.
Autor
Santos, Daniel Michelon dos
Institución
Resumen
This work uses data from the three components of wind and temperature, collected in
an experimental site in the Amazon rainforest for 10 months during GOAmazon Project. A
total of 10 levels of sensors were deployed on a micrometeorological tower. Focusing on the
nocturnal boundary layer, an analysis of the temporal scales of the motion, using the
multiresolution decomposition, has shown that the contributions from horizontal,
nonturbulent fluctuations with long temporal scales, can be as significant as purely turbulent
fluctuation. On, weakly stable nights the dominant temporal scales of the flow are those
associated with, downward (sweeps) and upward events (ejections), which occur with fullydeveloped
turbulence, , having dominant time scales between 10 and 100 s. Through the
analysis of two-point correlations, it was possible to show that horizontal events with long
time scales propagate from the top to within the canopy, being detected at different times,
and. The vertical component correlations are larger at the upper canopy, not showing any time
delay. The occurrence of positive sensible heat flux near the surface, with times scales larger
than 100 s, has been identified in the study of overall averages. It is hypothesized that on very
stable nights, non-turbulent modes associated with longer time scales, and referred as
"submeso" have great impact on the horizontal components, becoming an important cause of
the flow near the forest floor. In these situations, the most relevant time scales are longer than
300 a and dominate the almost entire vertical profile. For these cases, the correlations of
turbulent variables decay rapidly a, being between 0.2 and 0.3 for the horizontal components
while not exceeding 0.1 for the vertical component does. This reinforces the hypothesis that,
for this scenario, the most correlated events between the top of the canopy and its interior are
horizontal in nature.