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Title: Modelling bidirectional fluxes of methanol and acetaldehyde with the FORCAsT canopy exchange model

Here, the FORCAsT canopy exchange model was used to investigate the underlying mechanisms governing foliage emissions of methanol and acetaldehyde, two short chain oxygenated volatile organic compounds ubiquitous in the troposphere and known to have strong biogenic sources, at a northern mid-latitude forest site. The explicit representation of the vegetation canopy within the model allowed us to test the hypothesis that stomatal conductance regulates emissions of these compounds to an extent that its influence is observable at the ecosystem scale, a process not currently considered in regional- or global-scale atmospheric chemistry models. Here, we found that FORCAsT could only reproduce the magnitude and diurnal profiles of methanol and acetaldehyde fluxes measured at the top of the forest canopy at Harvard Forest if light-dependent emissions were introduced to the model. With the inclusion of such emissions, FORCAsT was able to successfully simulate the observed bidirectional exchange of methanol and acetaldehyde. Although we found evidence that stomatal conductance influences methanol fluxes and concentrations at scales beyond the leaf level, particularly at dawn and dusk, we were able to adequately capture ecosystem exchange without the addition of stomatal control to the standard parameterisations of foliage emissions, suggesting that ecosystem fluxes can be wellmore » enough represented by the emissions models currently used.« less
Authors:
ORCiD logo [1] ; ORCiD logo [2] ;  [3] ;  [4] ; ORCiD logo [5] ;  [5] ;  [6]
  1. Univ. of Michigan, Ann Arbor, MI (United States); Lancaster Univ. (United Kingdom)
  2. Washington State Univ., Pullman, WA (United States)
  3. Harvard Univ., Cambridge, MA (United States); Amherst College, Amherst, MA (United States)
  4. Harvard Univ., Cambridge, MA (United States); Amherst College, Amherst, MA (United States); Peking Univ., Beijing (China)
  5. Harvard Univ., Cambridge, MA (United States)
  6. Univ. of Michigan, Ann Arbor, MI (United States)
Publication Date:
Grant/Contract Number:
AGS1242203
Type:
Accepted Manuscript
Journal Name:
Atmospheric Chemistry and Physics (Online)
Additional Journal Information:
Journal Name: Atmospheric Chemistry and Physics (Online); Journal Volume: 16; Journal Issue: 24; Journal ID: ISSN 1680-7324
Publisher:
European Geosciences Union
Research Org:
Univ. of Michigan, Ann Arbor, MI (United States). Climate and Space Science and Engineering.
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
99 GENERAL AND MISCELLANEOUS
OSTI Identifier:
1375400