A model-based analysis of foliar NOx deposition
| Autor: | Erin R. Delaria, Ronald C. Cohen |
|---|---|
| Rok vydání: | 2020 |
| Předmět: |
Canopy
Atmospheric Science Ozone 010504 meteorology & atmospheric sciences Vapour Pressure Deficit chemistry.chemical_element 010501 environmental sciences 15. Life on land Atmospheric sciences 01 natural sciences Nitrogen chemistry.chemical_compound Water potential Deposition (aerosol physics) chemistry 13. Climate action Environmental science Ecosystem NOx 0105 earth and related environmental sciences |
| Zdroj: | Atmospheric Chemistry and Physics. 20:2123-2141 |
| ISSN: | 1680-7324 |
| DOI: | 10.5194/acp-20-2123-2020 |
| Popis: | Foliar deposition of NO2 removes a large fraction of the global soil-emitted NOx. Understanding the mechanisms of NOx foliar loss is important for constraining surface ozone, constraining NOx mixing ratios, and assessing the impacts of nitrogen inputs to ecosystems. We have constructed a 1-D multibox model with representations of chemistry and vertical transport to evaluate the impact of leaf-level processes on canopy-scale concentrations, lifetimes, and canopy fluxes of NOx. Our model is able to closely replicate canopy fluxes and above-canopy NOx daytime mixing ratios observed during two field campaigns, one in a western Sierra Nevada pine forest (BEARPEX-2009) and the other in a northern Michigan mixed hardwood forest (UMBS-2012). We present a conceptual argument for the importance of NO2 dry deposition and demonstrate that NO2 deposition can provide a mechanistic explanation for the canopy reduction of NOx. We show that foliar deposition can explain observations suggesting as much as ∼60 % of soil-emitted NOx is removed within forest canopies. Stomatal conductances greater than 0.1 cm s−1 result in modeled canopy reduction factors in the range of those used in global models, reconciling inferences of canopy NOx reduction with leaf-level deposition processes. We show that incorporating parameterizations for vapor pressure deficit and soil water potential has a substantial impact on predicted NO2 deposition in our model, with the percent of soil NOx removed within one canopy increasing by ∼15 % in wet conditions compared to dry conditions. NO2 foliar deposition was also found to have a significant impact on ozone and nitrogen budgets under both high- and low-NOx conditions. |
| Databáze: | OpenAIRE |
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