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The impact of model resolution on ozone simulation

As higher resolution models are widely used for various studies and predictions now, the change in model performance due to changes in the resolution itself should be better understood. This study is aiming to understand the impact of increased model resolution on the tropospheric ozone simulation in the chemical transport models. Using GEOS-Chem v12, two full chemistry runs with different horizontal resolution (4° x 5° and 2° x 2.5°) have been conducted for one year. The results show that when increasing the model resolution, the stratosphere-troposphere-exchange (STE) flux around the Upper Troposphere and Lower Stratosphere (UTLS) and chemical destruction of ozone decrease, while the chemical production of ozone increases. The tropospheric budget of ozone is generally closed. The changes of ozone at different vertical levels varies. On the surface, the changes is around 10% generally, but the change can be about 30% over some regions, which matters a lot in those regions. In the upper troposphere, the percentage changes seem to be smaller. The changes of ozone concentrations at different levels can be generally explain by the change in vertical mass flux. With the change in vertical mass flux and the STE, the ozone burden in the higher resolution run (2x25) decreases slightly.