Direct advection measurements do not help to solve the night-time CO2 closure problem: Evidence from three different forests

0348597 - ÚFA 2011 RIV NL eng J - Journal Article
Aubinet, M. - Feigenwinter, C. - Heinesch, B. - Bernhofer, C. - Canepa, E. - Lindroth, A. - Montagnani, L. - Rebmann, C. - Sedlák, Pavel - Van Gorsel, E.
Direct advection measurements do not help to solve the night-time CO2 closure problem: Evidence from three different forests.
Agricultural and Forest Meteorology. Roč. 150, č. 5 (2010), s. 655-664. ISSN 0168-1923. E-ISSN 1873-2240
R&D Projects: GA AV ČR IAA300420803
Grant - others:European Commission(XE) GOCECT2003-505572
Institutional research plan: CEZ:AV0Z30420517
Keywords : Advection * Forests * CO2 fluxes * Eddy covariance
Subject RIV: DG - Athmosphere Sciences, Meteorology
Impact factor: 3.228, year: 2010

The ADVEX project involved extensive advection measurements at three sites differing in topography. One aim of the project was to measure the CO2 balance in night-time conditions, in an attempt to improve NEE estimates. Horizontal advection varied greatly from site to site and from one wind sector to another, with the highest values reached at large friction velocities. The night-time NEE estimates deduced from the mass balance were incompatible with biologically driven fluxes because they varied strongly from one wind sector to another, their order of magnitude was not realistic and they still showed a trend vs. friction velocity. From a critical analysis of the measurement and data treatment we concluded that the causes of the problem are related to the measurement representativeness or the simplified CO2 mass balance equation used. This suggests that the improvement of eddy flux measurements by developing an advection-completed CO2 mass balance at night would be practically difficult.
Permanent Link: http://hdl.handle.net/11104/0189099