Measuring subcanopy CO2 advection in the FLONA Tapajós.
Julio
Tóta, LBA Project Office, INPA, Manaus AM, tota@lbaeco.com.br
(Presenting)
David
Roy
Fitzjarrald, Jungle Research Group, University at Albany, SUNY,, fitz@asrc.cestm.albany.edu
Ralf
M.
Staebler, ARQP, Meteorological Service of Canada, Toronto ON., ralf.staebler@ec.gc.ca
Ricardo
K.
Sakai, Jungle Research Group, University at Albany, SUNY,, sakai@asrc.cestm.albany.edu
At night, a shallow thermal inversion develops near the surface and deepens with time, under low wind speed conditions and radiational cooling. If terrain is not level, a drainage flow can develop. Above forests the flow above the canopy becomes decoupled from the flow just above and within canopy. It is possible that the drainage flow will carry respiratory CO2 from foliage, boles, and soil downslope. If this flow advects CO2 away from observation tower, some CO2 emission goes unmeasured. Eddy covariance systems above canopy will not detect this flux.
A horizontal gradient in CO2 coupled with a persistent flow in a certain direction, can create non-zero horizontal advection terms of the form (u)(dc/dx), terms commonly assumed to be zero. We report preliminary results from measurements of the horizontal advection of CO2, which may explain the “missing” vertical CO2 fluxes on frequent calm nights, when the eddy covariance technique fails to detect nocturnal respiration properly. The aim is to actually measure this term to determine its significance.
Submetido por David Roy Fitzjarrald em 25-MAR-2004
Tema Científico do LBA: CD (Armazenamento e Trocas de Carbono)