An ecosystem-scale perspective of the net land methanol flux: Synthesis of micrometeorological flux measurements
Goldstein, Allen H.
Munger, J. William
Pallardy, Stephen G.
Schade, Gunnar W.
- Journal Article
Rechte / LizenzCreative Commons Attribution 3.0 Unported
Methanol is the second most abundant volatile organic compound in the troposphereand plays a significant role in atmospheric chemistry. While there is consensus aboutthe dominant role of living plants as the major source and the reaction with OH asthe major sink of methanol, global methanol budgets diverge considerably in terms of source/sink estimates reflecting uncertainties in the approaches used to model,and the empirical data used to separately constrain these terms. Here we compiledmicrometeorological methanol flux data from eight different study sites and reviewedthe corresponding literature in order to provide a first cross-site synthesis of the ter-restrial ecosystem-scale methanol exchange and present an independent data-driven view of the land–atmosphere methanol exchange. Our study shows that the controls ofplant growth on the production, and thus the methanol emission magnitude, and stom-atal conductance on the hourly methanol emission variability, established at the leaflevel, hold across sites at the ecosystem-level. Unequivocal evidence for bi-directionalmethanol exchange at the ecosystem scale is presented. Deposition, which at some sites even exceeds methanol emissions, represents an emerging feature of ecosystem-scale measurements and is likely related to environmental factors favouring the forma-tion of surface wetness. Methanol may adsorb to or dissolve in this surface water andeventually be chemically or biologically removed from it. Management activities in agri-culture and forestry are shown to increase local methanol emission by orders of magnitude; they are however neglected at present in global budgets. While contemporarynet land methanol budgets are overall consistent with the grand mean of the microm-eteorological methanol flux measurements, we caution that the present approach ofsimulating methanol emission and deposition separately is prone to opposing system-atic errors and does not allow taking full advantage of the rich information content of micrometeorological flux measurements. Mehr anzeigen
Zeitschrift / SerieAtmospheric Chemistry and Physics Discussions
Seiten / Artikelnummer
Organisationseinheit03648 - Buchmann, Nina / Buchmann, Nina