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Simultaneous Measurements of O 3 and HCOOH Vertical Fluxes Indicate Rapid In‐Canopy Terpene Chemistry Enhances O 3 Removal Over Mixed Temperate Forests
Author(s) -
Vermeuel Michael P.,
Cleary Patricia A.,
Desai Ankur R.,
Bertram Timothy H.
Publication year - 2021
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2020gl090996
Subject(s) - flux (metallurgy) , eddy covariance , canopy , atmospheric sciences , ozone , deposition (geology) , tracer , chemistry , environmental chemistry , tree canopy , temperate climate , temperate forest , formic acid , temperate rainforest , decomposition , environmental science , ecosystem , botany , ecology , geology , geomorphology , physics , organic chemistry , chromatography , sediment , nuclear physics , biology
Dry deposition, the second largest removal process of ozone (O 3 ) in the troposphere, plays a role in controlling the natural variability of surface O 3 concentrations. Terrestrial ecosystems remove O 3 either through stomatal uptake or nonstomatal processes. In chemical transport models, nonstomatal pathways are roughly constrained and may not correctly capture total O 3 loss. To address this, the first simultaneous eddy covariance measurements of O 3 and formic acid (HCOOH), a tracer of in‐canopy oxidation of biogenic terpenes, were made in a mixed temperate forest in Northern Wisconsin. Daytime maximum O 3 deposition velocities, v d (O 3 ), ranged between 0.5 and 1.2 cm s −1 . Comparison of observed v d (O 3 ) with observationally constrained estimates of stomatal uptake and parameterized estimates of cuticular and soil uptake reveal a large (10%–90%) residual nonstomatal contribution to v d (O 3 ). The residual downward flux of O 3 was well correlated with measurements of HCOOH upward flux, suggesting unaccounted for in‐canopy gas‐phase chemistry.