Simulating ozone dry deposition at a boreal forest with a multi-layer canopy deposition model
A multi-layer ozone (O<sub>3</sub>) dry deposition model has been implemented into SOSAA (a model to Simulate the concentrations of Organic vapours, Sulphuric Acid and Aerosols) to improve the representation of O<sub>3</sub> concentration and flux within and above the forest...
| Main Authors: | , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2017-01-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | http://www.atmos-chem-phys.net/17/1361/2017/acp-17-1361-2017.pdf |
| Summary: | A multi-layer ozone (O<sub>3</sub>) dry deposition model has been implemented into SOSAA (a model to Simulate the concentrations of Organic vapours, Sulphuric
Acid and Aerosols) to improve the representation of O<sub>3</sub> concentration and flux within and above the forest canopy in the planetary boundary layer. We
aim to predict the O<sub>3</sub> uptake by a boreal forest canopy under varying
environmental conditions and analyse the influence of different factors on
total O<sub>3</sub> uptake by the canopy as well as the vertical distribution of
deposition sinks inside the canopy. The newly implemented dry deposition
model was validated by an extensive comparison of simulated and observed
O<sub>3</sub> turbulent fluxes and concentration profiles within and above the
boreal forest canopy at SMEAR II (Station to Measure Ecosystem–Atmosphere
Relations II) in Hyytiälä, Finland, in August 2010.
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In this model, the fraction of wet surface on vegetation leaves was
parametrised according to the ambient relative humidity (RH). Model results
showed that when RH was larger than 70 % the O<sub>3</sub> uptake onto wet skin
contributed ∼ 51 % to the total deposition during nighttime and
∼ 19 % during daytime. The overall contribution of soil uptake was
estimated about 36 %. The contribution of sub-canopy deposition below
4.2 m was modelled to be ∼ 38 % of the total O<sub>3</sub> deposition
during daytime, which was similar to the contribution reported in previous
studies. The chemical contribution to O<sub>3</sub> removal was evaluated directly in the model simulations. According to the simulated averaged diurnal cycle the net chemical production of O<sub>3</sub> compensated up to ∼ 4 % of dry deposition loss from about 06:00 to 15:00 LT.
During nighttime, the net chemical loss of O<sub>3</sub> further
enhanced removal by dry deposition by a maximum ∼ 9 %. Thus the results
indicated an overall relatively small contribution of airborne chemical
processes to O<sub>3</sub> removal at this site. |
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| ISSN: | 1680-7316 1680-7324 |