Coupling dry deposition to vegetation phenology in the Community Earth System Model: Implications for the simulation of surface O₃

Abstract

Dry deposition is an important removal process controlling surface ozone. We examine the representation of this ozone loss mechanism in the Community Earth System Model. We first correct the dry deposition parameterization by coupling the leaf and stomatal vegetation resistances to the leaf area index, an omission which has adversely impacted over a decade of ozone simulations using both the Model for Ozone and Related chemical Tracers (MOZART) and Community Atmospheric Model‐Chem (CAM‐Chem) global models. We show that this correction increases O3 dry deposition velocities over vegetated regions and improves the simulated seasonality in this loss process. This enhanced removal reduces the previously reported bias in summertime surface O3 simulated over eastern U.S. and Europe. We further optimize the parameterization by scaling down the stomatal resistance used in the Community Land Model to observed values. This in turn further improves the simulation of dry deposition velocity of O3, particularly over broadleaf forested regions. The summertime surface O3 bias is reduced from 30 ppb to 14 ppb over eastern U.S. and 13 ppb to 5 ppb over Europe from the standard to the optimized scheme, respectively. O3 deposition processes must therefore be accurately coupled to vegetation phenology within 3‐D atmospheric models, as a first step toward improving surface O3 and simulating O3 responses to future and past vegetation changes.

Tropospheric ozone and its precursors from the urban to the global scale from air quality to short-lived climate forcer

“…5. Correct parameterisation in models is critical to the determination of ozone budgets (Val-Martin et al, 2014).…”

“…isoprene - Archibald et al, 2010;Dunker et al, 2014;halogens -Yang et al, 2005;Saiz-Lopez et al, 2012a;and chemical mechanism -Saylor and Stein, 2012) and deposition (Val-Martin et al, 2014). For models to represent many of these processes, adequate resolution is required (Colette et al, 2014).…”

How emissions, climate, and land use change will impact mid-century air quality over the United States: a focus on effects at national parks

“…SOA formation is linked to the gas-phase chemistry through the oxidation of isoprene, monoterpenes, alkenes and toluene as in Lack et al (2004). Finally, dry deposition is represented by the multiple resistance approach of Wesely (1989), with some updates (Emmons et al, 2010;Lamarque et al, 2012;Val Martin et al, 2014). The calculation of dry deposition velocities is performed in CLM and linked to land cover types.…”

“…For example, large O 3 dry deposition velocities are associated with denser broadleaf forests (i.e., with high LAI) and crops (e.g., Wesely, 1989;Val Martin et al, 2014), whereas grasslands and needleleaf forests (i.e., with low LAI) are characterized by low deposition velocities. In our simulations, the O 3 dry deposition velocity generally shows a small decrease across the US (0.2-1.0 cm min −1 ; about 1-3 %) (Fig.…”

Evaluation of the MACC operational forecast system – potential and challenges of global near-real-time modelling with respect to reactive gases in the troposphere

“…The horizontal resolution is 0.5 • in latitude and longitude and it contains a monthly temporal resolution. Biogenic emissions are taken from Global Emissions InitiAtive (GEIA), fire emissions are based on a climatology derived from Global Fire Emissions Database version 2 (GFEDv2; van der Werf et al, 2006) until April 2010, when fire emissions change to global fire assimilation system (GFAS) emissions . Between January and October 2011 there has been a fire emission reading error in the model where, instead of adjusting emissions to the appropriate month, the same set of emissions have been read throughout this period.…”