Aspen Bibliography

Carbon Dioxide Exchange and Nocturnal Processes Over a Mixed Deciduous Forest

Document Type

Article

Journal/Book Title/Conference

Agricultural and Forest Meteorology

Volume

81

Issue

1-2

First Page

13

Last Page

29

Publication Date

1996

Abstract

This paper reports the results of the analysis of C O 2 exchange from a one-month experiment conducted at a mixed deciduous forest, Camp Borden (80065' W, 44019' N), Canada, in the summer of 1993. The mid-day CO2 flux from the forest under clear sky conditions was around

- 1.0mgm-2s-l,theaveragelightandwateruseefficiencies13mmolCO2(molphoton)-1and 7.95 mgCO2(gH20)-L, and the average noctumal respiration rate 0.21 mgCO2m-2 S-1.

We observed different flow features at heights of 34.5 (14.5 m above the canopy) and 22.4 m at night. Wavelike structures were frequently encountered at z = 34.5 m. Depending on the phase angle between the vertical velocity and CO2 concentration time series, they could act to enhance the co-gradient (upward) flux or to create counter-gradient(downward) flux of CO2. We speculate that the wave events were limited to isolated regions in the upwind direction. Near the tree-tops (z = 22.4 m), the strong wind shear was able to maintain turbulence. Inverse temperature ramp structures were very common and flux of sensible heat was well behaved (directed downward).

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