The STEM-2K3 is a regional chemical transport model, with the SAPRC99 mechanism (218 reactions), and all of the 30 photolysis rates are explicitly computed through its on-line TUV. Aerosol Ions are calculated by the on-line four-bin SCAPE II module, developed by CalTech and UC-Irvine. This page includes 5-layer horizontal plots of STEM-2K3 Forecasts over Northeastern USA in 12km horizontal resolution, which is nested within the STEM Forecast over North America. You can also view time-series or cross-section plots over any model grid. Welcome to send us comments.