A global simulation of tropospheric ozone and related tracers: Description and evaluation of MOZART, version 2

Abstract

[1] We have developed a global three-dimensional chemical transport model called Model of Ozone and Related Chemical Tracers (MOZART), version 2. This model, which will be made available to the community, is built on the framework of the National Center for Atmospheric Research (NCAR) Model of Atmospheric Transport and Chemistry (MATCH) and can easily be driven with various meteorological inputs and model resolutions. In this work, we describe the standard configuration of the model, in which the model is driven by meteorological inputs every 3 hours from the middle atmosphere version of the NCAR Community Climate Model (MACCM3) and uses a 20-min time step and a horizontal resolution of 2.8°latitude  2.8°longitude with 34 vertical levels extending up to approximately 40 km. The model includes a detailed chemistry scheme for tropospheric ozone, nitrogen oxides, and hydrocarbon chemistry, with 63 chemical species. Tracer advection is performed using a flux-form semi-Lagrangian scheme with a pressure fixer. Subgrid-scale convective and boundary layer parameterizations are included in the model. Surface emissions include sources from fossil fuel combustion, biofuel and biomass burning, biogenic and soil emissions, and oceanic emissions. Parameterizations of dry and wet deposition are included. Stratospheric concentrations of several long-lived species (including ozone) are constrained by relaxation toward climatological values. The distribution of tropospheric ozone is well simulated in the model, including seasonality and horizontal and vertical gradients. However, the model tends to overestimate ozone near the tropopause at high northern latitudes. Concentrations of nitrogen oxides (NO x ) and nitric acid (HNO 3 ) agree well with observed values, but peroxyacetylnitrate (PAN) is overestimated by the model in the upper troposphere at several locations. Carbon monoxide (CO) is simulated well at most locations, but the seasonal cycle is underestimated at some sites in the Northern Hemisphere. We find that in situ photochemical production and loss dominate the tropospheric ozone budget, over input from the stratosphere and dry deposition. Approximately 75% of the tropospheric production and loss of ozone occurs within the tropics, with large net production in the tropical upper troposphere. Tropospheric production and loss of ozone are three to four times greater in the northern extratropics than the southern extratropics. The global sources of CO consist of photochemical production (55%) and direct emissions (45%). The tropics dominate the chemistry of CO, accounting for about 75% of the tropospheric production and loss. The global budgets of tropospheric ozone and CO are generally consistent with the range found in recent studies. The lifetime of methane (9.5 years) and methylchloroform (5.7 years) versus oxidation by tropospheric hydroxyl radical (OH), two useful measures of the global abundance of OH, agree well with recent estimates. Concentrations of nonmethane hydrocarbons and oxygenated intermediates (carbony...

Trace gas and aerosol interactions in the fully coupled model of aerosol‐chemistry‐climate ECHAM5‐HAMMOZ: 1. Model description and insights from the spring 2001 TRACE‐P experiment

“…[11] The MOZ chemical scheme is identical to the one used in the MOZART-2 model [Horowitz et al, 2003] Fiore et al [2005]. Isoprene nitrates produced from the reaction of NO with the isoprene-derived peroxy radicals now correspond to a NOx sink as they are converted directly to HNO 3 .…”

“…These concentrations are fixed at the topmost two model levels (pressures of 30 hPa and above). At other model levels above the tropopause, the concentrations are relaxed toward these values with a relaxation time of 10 days following Horowitz et al [2003]. The tropopause height is diagnosed as the lowest level at which the lapse rate decreases to 2°C per kilometer or less following the World Meteorological Organization definition [World Meteorological Organization, 1992].…”

Systematic analysis of tropospheric NO<sub>2</sub> long-range transport events detected in GOME-2 satellite data

“…Usually, the cloud-free air-mass factor is determined either from a standard atmospheric profile or from climatological simulations (like MOZART, Horowitz et al, 2003). These cannot, however, be used for analysis of long-range transport events, as the NO 2 will typically be strongly localized in altitude (Rastigejev et al, 2010) and deviate from stationary conditions.…”

“…We have used MACC-II (Monitoring Atmospheric Composition and Climate -Interim Implementation) reanalysis (Inness et al, 2013) liquid and frozen water content and NO 2 concentrations to find further indications of the relation in altitude between clouds and NO 2 for a prominent case of an NO 2 long-range transport event linked to clouds (Fig. 3).…”

A pathway analysis of global aerosol processes

“…The processes described in M7 cause redistribution of aerosol mass and numbers among the modes. Part of HAM is a sulfur cycle model (Feichter et al, 1996) that predicts the evolution of dimethyl sulfide (DMS), sulfur dioxide (SO 2 ) and gaseous sulfate (SO − 4 ) using monthly mean fields of the oxidants OH, H 2 O 2 , NO 2 and O 3 , calculated off-line by the MOZART (model for ozone and related chemical tracers) chemical transport model (Horowitz et al, 2003). The aerosol in HAM is affected by the meteorology calculated by ECHAM, and in turn provides feedback to ECHAM as it affects atmospheric radiative transfer and cloud microphysics.…”