1. Overview of the tracer code in RegCM Tracers Aerosols ( droplets, smoke particles, dust, pollens, flying cats …) Gazeous phase, chemical species Evolution of concentration (mixing ratio) TransportRemoval terms Primary Emissions Physico – chemical transformations Strongly dependant on the nature of the tracer Qian and Giorgi, 1999

2. Horizontal and vertical advection Horizontal and vertical diffusion derived from water vapor and cloud water (mm4 Anthes et al., 1987) T CUM « Well-mixing approximation » Rq : Tan et al., 2002 scheme ( work with Kuo-scheme) Mass flux / Grell, Emmanuel schemes « Wet deposition » Giorgi, and Chameides, 1986 Giorgi, 1989 Surface emissions Chemistry Input data SO 4 -- SO 2 Qian and Giorgi, 2001 Not integrated yet Dry deposition Fixed deposition velocities

3. Optical properties of the tracer Specific extinction Single scattering albedo Radiative transfer model ( CCM3 rad pack) Assymetry parameter Pronostic concentrations Fixed and characteristic of sulfates in our example The indirect effect (e.g. Qian and Giorgi, 1999) is not taken into account in the present version on the code Direct effect

4. Source defined from GEIA 97 (BC) No chemistry Direct effect only (diffusive properties) Application : One « generic tracer » ….Before the simulation ….. Download Chemsrc.tar.gz file from the webpage http://www.ictp.trieste.it/~pubregcm/RegCM3/patch.html and copy it in RegCM / Preproc directory. Unzip and extract ( tar zxvf Chemsrc.tar.gz) … you should have a new Chemsrc directory … Go to the RegCM / Preproc directory and remove the Chemsrc directory rm –R Chemsrc PATCH

5. Prepare : Terrain / ICBC for june 1997 (with the same domain as practise run) ……… Preparation of tracer sources (interpolation of a global data set on the RegCM domain) 1997060100 1997070100 Preproc step Run the chsrfem.x script It generates the file CHEM-BC97 in RegCM/Input directory go to RegCM/Preproc/Chemsrc

6. Run the model with tracer options edit regcm.in Create a new run directory for running tracer simulations Ex : RegCM / PractiseTrac Link the emission file into this run directory ln –sf../Input/CHEM-BC97. Simulation with tracers Copy the regcm.x and regcm.in from the Regcm / Commons directory in the PractiseTrac directory 5 days 1997060100 – 1997060500

7. Post-processing with vis5D Go to the directory Postproc-v5d and link here the simulation output fields : ln –sf../ PractiseTrac /output/ATM.1997060100. ln –sf../ PractiseTrac /output/CHE.1997060100. ln –sf../ PractiseTrac /output/RAD.1997060100. …. Before the post processing …. Remove the RegCM/Postproc-v5d directory Download the Postproc-v5d.tar.gz file and extract it in the RegCM directory PATCH

8. In Postproc-v5d Edit the postpv5d.in and set the control parameters Edit the postpv5d.param and set the run parameters Execute the postpv5d.x … it generates the P_OUT.v5d file ( if pressure grid) Execute vis5d P_OUT.v5d to visualise the file