Horizontal Advection of CO2 in the Old Growth Forest: LBA preliminary results
Julio
Tota da
Silva, INPA, tota@lbaeco.com.br
(Presenting)
David
Roy
Fitzjarrald, SUNNY Albany, fitz@asrc.cestm.albany.edu
Ralf
M.
Staebler, CD-03, ralf.staebler@ec.gc.ca
Ricardo
K.
Sakai, SUNNY Albany, sakai@asrc.cestm.albany.edu
At night, under low wind speed conditions and radiational cooling, a shallow thermal inversion develops near the ground surface and deepens with time. If the terrain is not level, a drainage flow (katabatic wind) will develop. In the forest ecosystem the flow above the canopy becomes decoupled from the flow just above and within the canopy. Therefore, drainage flow will carry respiration from foliage, boles, and soil downslope. Eddy covariance systems above the canopy will not detect this flux and subcanopy sensors are likely to grossly underestimate it. A horizontal gradient in CO2, coupled with a persistent flow in a specific direction, can create non-zero horizontal advection terms of the form (u)(dc/dx), which
are commonly assumed to be zero. We collect data at Flona Tapajos Old Growth Site with a net system during July and August 2003 continuously.
In this presentation, we will show preliminary results from horizontal CO2 advection measurements, which may explain the missing vertical CO2 fluxes on calm nights, when the eddy covariance technique fails to properly detect nocturnal respiration. The aim is to measure these advection terms and determine their significance. We will be present to discuss aspects of spatial and temporal variability.
Submetido por Julio Tota da Silva em 18-MAR-2004
Tema Científico do LBA: CD (Armazenamento e Trocas de Carbono)