Comparing micrometeorology of rain forests in Biosphere-2 and Amazon basin

Micrometeorological variables measured in the BIOSPHERE-2 Center (B2C) encl osed rain forest biome for 1 year were compared with similar measurements m ade in the Amazon rain forest, In the B2C rain forest, the overlying glass and supporting structure significantly reduces (by approximately a factor o f two) the incoming solar radiation. Monthly mean values of above-canopy an d within-canopy air temperature, vapor pressure, and vapor pressure deficit are reasonably similar to chose of the Amazon rain forest, but there are m arked differences in the above-canopy values of these variables in the Ariz ona summer. Monthly mean diurnal trends also show significant differences. Measurements of vertical air temperature gradient clearly showed two very d istinct environments in the 27.4 m high rain forest dome during daylight ho urs. There is a comparatively cool and fairly well-mixed environment (which is reasonably similar to that found in a natural rain forest) below about 10 m and a hot, thermally stable environment above about 15 m. The nature o f the atmospheric turbulence within the B2C rain forest also is significant ly different from that normally found in natural rain forests. There is lit tle turbulent mixing above the forest canopy in this enclosed environment. These findings are important for guiding the operation and use of this expe rimental rain forest facility in future research and for understanding how the rain forest biome functions in an enclosed environment. (C) 2000 Elsevi er Science B.V. All rights reserved.