TY - JOUR
T1 - Long-term tall tower carbon dioxide flux monitoring over an area of mixed vegetation
AU - Haszpra, L.
AU - Barcza, Z.
AU - Davis, K. J.
AU - Tarczay, K.
N1 - Funding Information:
Use of the tower is kindly provided by Antenna Hungária Corporation. The project was supported by the U.S.-Hungarian Scientific and Technological Joint Fund (J.F. no. 504 [1996–1999]), by the Hungarian National Scientific Research Fund (OTKA T23811 [1997–2000], OTKA F026642 [1998–2001], OTKA T32440 [2001–2004], OTKA T42941 [2003–2006], OTKA F047242 [2004–2006]), by the Hungarian Higher Education Support Program (FKFP-0168/1997), by the EC's Fifth R&D Framework Programme (AEROCARB and CHIOTTO, Contract No. EVK2-CT-1999-00013 and EVK2-CT-2002-00163), by the EC's Sixth R&D Framework Programme (CARBOEUROPE-IP, Contract No. GOCE-CT-2003-505572) and by the Bolyai Scholarship of the Hungarian Academy of Sciences (Z. Barcza).
Copyright:
Copyright 2008 Elsevier B.V., All rights reserved.
PY - 2005/9/20
Y1 - 2005/9/20
N2 - A methodology is described to determine the carbon budget of an extended region with mixed vegetation. The eddy covariance measuring system is operated at 82 m elevation on a tall radio/television transmitter tower above an area covered by agricultural fields and forest patches. The methodology ensuring the high quality of the calculated fluxes is described. Net ecosystem exchange (NEE) of CO2 is determined as the sum of the eddy flux at 82 m and the rate of change of CO2 storage below the measurement level. The gap filling technique used to patch the missing measurements is also presented. In contrast to several long-term NEE measurements low turbulent conditions does not seem to bias the annual sums of NEE at the site. Maximum daytime NEE reached -1.4 to -1.5 mg CO2 m-2 s-1 (negative value indicates uptake) during the most active phase of the vegetation, while mean night-time respiration was around 0.1-0.3 mg CO2 m-2 s-1. During the dormant season typical net exchange was around 1 g C m-2 day-1, while the vegetation adsorbed around 2-4 g C m-2 day-1 in the growing season. The overall dependence of the landscape-wide NEE on the environmental factors is described with non-linear regression functions. It is demonstrated that tall tower NEE measurements may provide repeatable, consistent estimates of the landscape-wide carbon exchange. The results may contribute to a better constraint on the "bottom-up" flux estimates. During the period of 1997-2004 (year 2000 is missing) the region mostly behaved as a weak net CO2 sink on annual scale. Year-round NEE was in the range of -107 ± 48 and 69 ± 37 g C m-2 year-1. Climate data are presented to explain the interannual variability of NEE, gross primary production (GPP) and total ecosystem respiration (Reco).
AB - A methodology is described to determine the carbon budget of an extended region with mixed vegetation. The eddy covariance measuring system is operated at 82 m elevation on a tall radio/television transmitter tower above an area covered by agricultural fields and forest patches. The methodology ensuring the high quality of the calculated fluxes is described. Net ecosystem exchange (NEE) of CO2 is determined as the sum of the eddy flux at 82 m and the rate of change of CO2 storage below the measurement level. The gap filling technique used to patch the missing measurements is also presented. In contrast to several long-term NEE measurements low turbulent conditions does not seem to bias the annual sums of NEE at the site. Maximum daytime NEE reached -1.4 to -1.5 mg CO2 m-2 s-1 (negative value indicates uptake) during the most active phase of the vegetation, while mean night-time respiration was around 0.1-0.3 mg CO2 m-2 s-1. During the dormant season typical net exchange was around 1 g C m-2 day-1, while the vegetation adsorbed around 2-4 g C m-2 day-1 in the growing season. The overall dependence of the landscape-wide NEE on the environmental factors is described with non-linear regression functions. It is demonstrated that tall tower NEE measurements may provide repeatable, consistent estimates of the landscape-wide carbon exchange. The results may contribute to a better constraint on the "bottom-up" flux estimates. During the period of 1997-2004 (year 2000 is missing) the region mostly behaved as a weak net CO2 sink on annual scale. Year-round NEE was in the range of -107 ± 48 and 69 ± 37 g C m-2 year-1. Climate data are presented to explain the interannual variability of NEE, gross primary production (GPP) and total ecosystem respiration (Reco).
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U2 - 10.1016/j.agrformet.2005.07.002
DO - 10.1016/j.agrformet.2005.07.002
M3 - Article
AN - SCOPUS:24944468106
SN - 0168-1923
VL - 132
SP - 58
EP - 77
JO - Agricultural and Forest Meteorology
JF - Agricultural and Forest Meteorology
IS - 1-2
ER -