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Quantifying the impacts of resolution-dependent model transport errors on the tropospheric ozone simulations

One factor that could have an impact of the fidelity of model simulations of ozone in the Chemical Transport Models (CTMs) is model resolution. To quantify and isolate the resolution dependent impacts on the ozone budget, we have conducted full-chemistry runs and tagged ozone runs with different horizontal resolutions 4°x5° and 2°x2.5° in GEOS-Chem. We find that increasing the model resolution results in a reduction in stratosphere-to-troposphere exchange (STE). In the tropics there is always stronger convective transport in the higher resolution model. We find that the dominant source of the ozone differences in the subtropical and extratropical upper troposphere is the change in STE between the two model resolutions. In the middle and lower troposphere, the ozone differences are driven by changes in the chemical production of ozone and vertical transport of ozone. Evaluation of the models with ozonesonde data confirms that the ozone simulation is improved at the higher resolution. Applying online convection scheme in GEOS-Chem can reproduce part of the lost convective mass fluxes in the lower resolution model. The effects of online convection module will be discussed as well.

Event series  Brewer-Wilson Seminar Series