Role of oceanic ozone deposition in explaining temporal variability in surface ozone at High Arctic sites

• Published in: Atmospheric Chemistry and Physics
• Main Authors: Barten, Johannes G.M., Ganzeveld, Laurens N., Steeneveld, Gert Jan, Krol, Maarten C.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2021
• Subjects: Life Science; Arctic; Arctic Ocean; Sea ice
• Online Access: https://research.wur.nl/en/publications/role-of-oceanic-ozone-deposition-in-explaining-temporal-variabili; https://doi.org/10.5194/acp-21-10229-2021

Dry deposition is an important removal mechanism for tropospheric ozone (O3). Currently, O3 deposition to oceans in atmospheric chemistry and transport models (ACTMs) is generally represented using constant surface uptake resistances. This occurs despite the role of solubility, waterside turbulence and O3 reacting with ocean water reactants such as iodide resulting in substantial spatiotemporal variability in O3 deposition and concentrations in marine boundary layers. We hypothesize that O3 deposition to the Arctic Ocean, having a relatively low reactivity, is overestimated in current models with consequences for the tropospheric concentrations, lifetime and long-range transport of O3. We investigate the impact of the representation of oceanic O3 deposition to the simulated magnitude and spatiotemporal variability in Arctic surface O3. We have integrated the Coupled Ocean-Atmosphere Response Experiment Gas transfer algorithm (COAREG) into the mesoscale meteorology and atmospheric chemistry model Polar-WRF-Chem (WRF) which introduces a dependence of O3 deposition on physical and biogeochemical drivers of oceanic O3 deposition. Also, we reduced the O3 deposition to sea ice and snow. Here, we evaluate WRF and CAMS reanalysis data against hourly averaged surface O3 observations at 25 sites (latitudes > 60° N). This is the first time such a coupled modeling system has been evaluated against hourly observations at pan-Arctic sites to study the sensitivity of the magnitude and temporal variability in Arctic surface O3 on the deposition scheme. We find that it is important to nudge WRF to the ECMWF ERA5 reanalysis data to ensure adequate meteorological conditions to evaluate surface O3. We show that the mechanistic representation of O3 deposition over oceans and reduced snow/ice deposition improves simulated Arctic O3 mixing ratios both in magnitude and temporal variability compared to the constant resistance approach. Using COAREG, O3 deposition velocities are in the order of 0.01 cm s-1 compared to ∼ 0.05 cm s-1 in ...