Study of the Earth's Ozone Layer Evolution Using a New Version of the INM RAS - RSHU Chemistry-Climate Model

Abstract. Numerical experiments were conducted using a chemical-climate model based on the INMCM60 model. The evolution of ozone in the atmosphere was analyzed.

Keywords. Numerical experiments, tropospheric chemistry, bromine chemistry, ozone concentration, total ozone content.

The main method of this study is numerical modeling of atmospheric processes. Changes in the main meteorological parameters (air temperature and humidity, atmospheric pressure, air density and wind speed) are described by the equations of thermodynamics, conservation of water vapor, air state, continuity and motion of the atmosphere. These equations are solved by numerical methods. Non-adiabatic processes associated with solar radiation, turbulence, convection and the influence of the underlying surface on the atmosphere are taken into account by parametrization. The evolution of gas impurities is determined using their transport equations, which are also solved by finite-difference methods; in this case, the rates of chemical reactions are determined to solve this problem. The dynamic and chemical parts of the model exchange calculated data, which allows taking into account the influence of all these processes on each other.

In this work, we used a chemistry-climate model based on the INM RAS model version 6 (INMCM60), which contains, in addition to the dynamic and chemical blocks, aerosol and oceanic blocks. The exchange between the dynamic and aerosol blocks occurs by analogy with the exchange with the chemical block. The exchange with the oceanic block occurs only after all 3 blocks (dynamic, chemical and aerosol) have performed calculations for 1 time step. Also, in this model, you can change the resolution by longitude and latitude. In this paper, experiments were conducted with 50 longitude and 40 latitude (the number of nodes in the model is 72 in longitude and 45 in latitude, the time step is 7 minutes 30 seconds) and with 20 longitude and 1.50 latitude (the number of nodes in the model is 180 in longitude and 120 in latitude, the time step is 2 minutes 75 seconds). Vertically, the number of σ-levels of the model is 73 (from 0 to 60 km or from the surface to the level of 0.2 hPa), while the modeling results are interpolated into an isobaric coordinate system on 26 standard isobaric surfaces. For the oceanic block, the resolution is 1x0.5 (for the 5x4 version) and 0.5x0.25 (for the 2x1.5 version). The model updates the initial data every 6 hours (4 times a day). Numerical experiments were conducted using this model. In the 5x4 version, an experiment was conducted without the chemistry-atmosphere interactive (taking into account the feedback effect of gas impurities on atmospheric processes) and an experiment with this interactive. Also, experiments were conducted using the 2x1.5 model with and without the interactive with different versions of the chemical block: chemistry with tropospheric and bromine components, chemistry with an emphasis on tropospheric components. Changes in the concentration and total content of ozone were analyzed.

The results of the experiments were also used as initial and boundary conditions for modeling using the WRF-chem model for St. Petersburg and the Russian North.