Improvements to the WRF-Chem 3.5.1 model for quasi-hemispheric simulations of aerosols and ozone in the Arctic

• Published in: Geoscientific Model Development Vol. 10; no. 10; pp. 3661 - 3677
• Main Authors: Marelle, Louis, Raut, Jean-Christophe, Law, Kathy S, Berg, Larry K, Fast, Jerome D, Easter, Richard C, Shrivastava, Manish, Thomas, Jennie L
• Format: Journal Article
• Language: English
• Published: Katlenburg-Lindau Copernicus GmbH 09.10.2017; European Geosciences Union; Copernicus Publications
• Subjects: Aerosol effects; Aerosols; Air pollution; Airborne sensing; Albedo; Albedo (solar); Aqueous chemistry; Arctic ozone; Atmospheric and Oceanic Physics; Atmospheric chemistry; Atmospheric ozone; Black carbon; Boundary conditions; Carbon; Case studies; Chemistry; Cloud parameterization; Clouds; Computer simulation; Cumulus clouds; Deposition; Dimethyl sulfide; Dry deposition; Emission measurements; Emissions; Environmental aspects; ENVIRONMENTAL SCIENCES; Evaluation; Gases; Ice cover; Land surface models; Ozone; Parameterization; Photolysis; Physics; Polar environments; Pollutants; Profiles; Representations; Root-mean-square errors; Sea ice; Sea ice temperatures; Sedimentation; Sedimentation & deposition; Simulation; Snow; Snow and ice; Sulfates; Sulphides; Surface temperature; Trace gases; Troposphere; Ultraviolet radiation; Upper troposphere; Volatility; Weather; Arctic; Arctic region
• ISSN: 1991-9603; 1991-959X; 1991-962X; 1991-9603; 1991-962X; 1991-959X
• DOI: 10.5194/gmd-10-3661-2017

In this study, the WRF-Chem regional model is updated to improve simulated short-lived pollutants (e.g., aerosols, ozone) in the Arctic. Specifically, we include in WRF-Chem 3.5.1 (with SAPRC-99 gas-phase chemistry and MOSAIC aerosols) (1) a correction to the sedimentation of aerosols, (2) dimethyl sulfide (DMS) oceanic emissions and gas-phase chemistry, (3) an improved representation of the dry deposition of trace gases over seasonal snow, and (4) an UV-albedo dependence on snow and ice cover for photolysis calculations. We also (5) correct the representation of surface temperatures over melting ice in the Noah Land Surface Model and (6) couple and further test the recent KF-CuP (Kain–Fritsch + Cumulus Potential) cumulus parameterization that includes the effect of cumulus clouds on aerosols and trace gases. The updated model is used to perform quasi-hemispheric simulations of aerosols and ozone, which are evaluated against surface measurements of black carbon (BC), sulfate, and ozone as well as airborne measurements of BC in the Arctic. The updated model shows significant improvements in terms of seasonal aerosol cycles at the surface and root mean square errors (RMSEs) for surface ozone, aerosols, and BC aloft, compared to the base version of the model and to previous large-scale evaluations of WRF-Chem in the Arctic. These improvements are mostly due to the inclusion of cumulus effects on aerosols and trace gases in KF-CuP (improved RMSE for surface BC and BC profiles, surface sulfate, and surface ozone), the improved surface temperatures over sea ice (surface ozone, BC, and sulfate), and the updated trace gas deposition and UV albedo over snow and ice (improved RMSE and correlation for surface ozone). DMS emissions and chemistry improve surface sulfate at all Arctic sites except Zeppelin, and correcting aerosol sedimentation has little influence on aerosols except in the upper troposphere.