Liu, F: Set-up and Incorporation of an Atmospheric Chemistry

The general aim as formulated at the start of this Ph.D. research has been to compose a state-of-the-art three-dimensional regional scale atmospheric transport chemistry model (CTM) which can be used for both long-term tropospheric chemistry and regional air quality simulations. REMO has been extended by a photo-chemical reaction scheme, ReLACS (Crassier et al., 2000) as a secondary lumped chemistry mechanism of the RACM (Stockwell et al., 1997) is used for that purpose. A program that allows on-line photolysis rate calculations (FAST-J2) (Wild et al., 2000) and an efficient ODE solver (CHEMEQ2) based on \alpha-QSS approach (Mott et al, 2000; Mott and Oran et al., 2001) are utilized. We refer to this extended REMO as RECCM (REgional Climate Chemistry Model). With the aid of this model the processes and their interactions that control the chemical composition of the troposphere can be investigated.
In order to reach the aim described above the first step is to build up and validate the chemical module, which is one of the most important components in the 3-D model. With well-designed scenarios (Poppe et al., 2001) a validation test of the chemical module was carried out using our box model. The test results was analyzed and evaluated through comparing with reference based on RACM.
The processes involved in continuity equation of species include horizontal advection, vertical advection and turbulent diffusion, re-distribution due to cumulus convective system, chemical transformation, dry deposition and emission rates. The appropriate numerical schemes for solving each process by operator splitting are proposed. The interface between REMO and the chemical module is developed through which the real time variables, i.e., cloud optical depth, surface albedo, pressure and temperature profiles from REMO are transferred into chemical module for chemical rate constants and photolysis rates calculations at each time step. The modeled ozone profile is used for ozone input