Summertime Observations of Ozone Deposition to a Mixed Temperate Forest
Abstract
A significant removal process for ambient ozone (O3) is through dry deposition to terrestrial landforms, with deposition rates varying intensely with vegetation class (e.g. forest, wetland, grassland, shrubs). Forests have long been considered efficient sinks for O3 and other atmospheric pollutants, influencing atmospheric composition and biosphere productivity and thus atmosphere-biosphere feedbacks. The major loss pathways of O3 to a forest are through stomatal uptake and the ozonolysis of biogenic volatile organic compounds (BVOC), both of which have rates that increase with leaf temperature and peak in the summertime. Here we present observations of O3 deposition to the mixed landscape of the Chequamegon-Nicolet National Forest in Park Falls, WI as part of the Chequamegon Heterogeneous Ecosystem Energy-balance Study Enabled by a High-density Extensive Array of Detectors (CHEESEHEAD) field campaign for measuring surface energy fluxes over heterogeneous land cover. Throughout July 2019 continuous O3 concentration measurements were made from the WLEF very tall tower at both 30- and 122-m heights using a chemical ionization time of flight mass spectrometer (CI-ToFMS) in oxygen anion (O2-) mode and a Thermo Fisher Model 49i Ozone Analyzer to quantify a gradient in O3 above and approaching the top of the forest canopy. The CI-ToFMS was also employed to make eddy-covariance measurements of O3 and other atmospheric pollutants at both heights through varying meteorological conditions that control O3 removal processes. The observations from this study will allow us to assess the influence of a mixed forest on ambient O3 removal as well as the dependence of the deposition magnitude on the variation in measurement footprint over a heterogenous surface and on the distance from the canopy height.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.A23M2868V
- Keywords:
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- 0315 Biosphere/atmosphere interactions;
- ATMOSPHERIC COMPOSITION AND STRUCTURE;
- 0322 Constituent sources and sinks;
- ATMOSPHERIC COMPOSITION AND STRUCTURE;
- 0365 Troposphere: composition and chemistry;
- ATMOSPHERIC COMPOSITION AND STRUCTURE;
- 0414 Biogeochemical cycles;
- processes;
- and modeling;
- BIOGEOSCIENCES