Sensitivity of chemical tracers to meteorological parameters in the MOZART‐3 chemical transport model

TLDR

The study examines how the quasi‑biennial oscillation circulation influences long‑lived atmospheric tracers and ozone. Using the MOZART‑3 chemical transport model driven by three meteorological fields—WACCM1b, ECMWF operational analysis, and the ECMWF EXP471 reanalysis—the authors compared model‑derived methane, water vapor, total inorganic nitrogen, and ozone to satellite climatologies and assessed mean age of air against in‑situ CO₂ and SF₆ observations. The analysis shows that small wind and temperature differences between the dynamical fields lead to substantial tracer distribution changes, with WACCM1b and EXP471 providing the best agreement for long‑lived tracers and mean age of air, and EXP471 yielding a significant improvement over the operational product.

Abstract

The Model for Ozone and Related Chemical Tracers, version 3 (MOZART‐3), which represents the chemical and physical processes from the troposphere through the lower mesosphere, was used to evaluate the representation of long‐lived tracers and ozone using three different meteorological fields. The meteorological fields are based on (1) the Whole Atmosphere Community Climate Model, version 1b (WACCM1b), (2) the European Centre for Medium‐Range Weather Forecasts (ECMWF) operational analysis, and (3) a new reanalysis for year 2000 from ECMWF called EXP471. Model‐derived tracers (methane, water vapor, and total inorganic nitrogen) and ozone are compared to data climatologies from satellites. Model mean age of air was also derived and compared to in situ CO 2 and SF 6 data. A detailed analysis of the chemical fields simulated by MOZART‐3 shows that even though the general features characterizing the three dynamical sets are rather similar, slight differences in winds and temperature can produce substantial differences in the calculated distributions of chemical tracers. The MOZART‐3 simulations that use meteorological fields from WACCM1b and ECMWF EXP471 represented best the distribution of long‐lived tracers and mean age of air in the stratosphere. There was a significant improvement using the ECMWF EXP471 reanalysis data product over the ECMWF operational data product. The effect of the quasi‐biennial oscillation circulation on long‐lived tracers and ozone is examined.