Daytime turbulent exchange between the Amazon forest and the atmosphere
- State Univ. of New York, Albany (USA)
- Centro Nacional de Pesquisa da Seringueira e Dende-Embrapa, Manaus (Brazil)
- Universidade de Sao Paulo (Brazil)
- Instituto de Pesquisas Espaciais, Sao Paulo (Brazil)
Detailed observations of turbulence just above and below the crown of the Amazon rain forest during the wet season are presented. The forest canopy is shown to remove high-frequency turbulent fluctuations while passing lower frequencies. Filter characteristics of turbulent transfer into the Amazon rain forest canopy are quantified. In spite of the ubiquitous presence of clouds and frequent rain during this season, the average horizontal wind speed spectrum and the relationship between the horizontal wind speed and its standard deviation are well described by dry convective boundary layer similarity hypotheses originally found to apply in flat terrain. Diurnal changes in the sign of the vertical velocity skewness observed above and inside the canopy are shown to be plausibly explained by considering the skewness budget. Simple empirical formulas that relate observed turbulent heat fluxes to horizontal wind speed and variance are presented. Changes in the amount of turbulent coupling between the forest and the boundary layer associated with deep convective clouds are presented in three case studies. Even small raining clouds are capable of evacuating the canopy of substances normally trapped by persistent static stability near the forest floor. Recovery from these events can take more than an hour, even during midday.
- OSTI ID:
- 5937900
- Journal Information:
- Journal of Geophysical Research; (USA), Vol. 95:D10; ISSN 0148-0227
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
CANOPIES
AIR-BIOSPHERE INTERACTIONS
WIND
TURBULENT FLOW
AMAZON RIVER
ATMOSPHERIC PRECIPITATIONS
BOUNDARY LAYERS
BRAZIL
CLOUDS
DAILY VARIATIONS
EARTH ATMOSPHERE
FLOW MODELS
FLUCTUATIONS
FORESTS
HEAT FLUX
MASS TRANSFER
MONITORING
RAIN
SEASONAL VARIATIONS
TURBULENCE
VELOCITY
DEVELOPING COUNTRIES
FLUID FLOW
LATIN AMERICA
LAYERS
MATHEMATICAL MODELS
RIVERS
SOUTH AMERICA
STREAMS
SURFACE WATERS
VARIATIONS
540110*
540210 - Environment
Terrestrial- Basic Studies- (1990-)