Intercomparison Between Surrogate, Explicit, and Full Treatments of VSL Bromine Chemistry Within the CAM‐Chem Chemistry‐Climate Model
Rafael P. Fernández, Javier A. Barrera, Ana Lopez-Noreña, Douglas E. Kinnison, Julie M. Nicely, R. J. Salawitch, Pamela Wales, Beatriz M. Toselli, Simone Tilmes, Jean‐François Lamarque, Carlos A. Cuevas, Alfonso Saiz‐Lopez
Abstract
Abstract Many Chemistry‐Climate Models (CCMs) include a simplified treatment of brominated very short‐lived (VSL Br ) species by assuming CH 3 Br as a surrogate for VSL Br . However, neglecting a comprehensive treatment of VSL Br in CCMs may yield an unrealistic representation of the associated impacts. Here, we use the Community Atmospheric Model with Chemistry (CAM‐Chem) CCM to quantify the tropospheric and stratospheric changes between various VSL Br chemical approaches with increasing degrees of complexity (i.e., surrogate, explicit, and full). Our CAM‐Chem results highlight the improved accuracy achieved by considering a detailed treatment of VSL Br photochemistry, including sea‐salt aerosol dehalogenation and heterogeneous recycling on ice‐crystals. Differences between the full and surrogate schemes maximize in the lowermost stratosphere and midlatitude free troposphere, resulting in a latitudinally dependent reduction of ∼1–7 DU in total ozone column and a ∼5%–15% decrease of the OH/HO 2 ratio. We encourage all CCMs to include a complete chemical treatment of VSL Br in the troposphere and stratosphere.