Valuation of a Lagrangian Operational Ozone Prediction Model (LOOP)

Abstract

Since July 1995 German Law mandates vehicles without catalytic converters to be banned from traffic when measured ozone mixing ratios exceed 120 ppb and will be likely to exceed this value the day after. Therefore, daily ozone forecasts are needed. In order to replace currently used statistical models the DWD develops chemistry and transport models. One important restriction to be met is a time limit of 2 hours CPU-time for a three-day forecast on the DWD computers. On the Cray YMP4 available until this year this restricts the DWD to use a trajectory box model. A 3-D Eulerian model can only be used after an extensive up-grade of computer power which has just been started and will be continued during the next six years. The trajectory box model provides the additional advantage of giving insight into the couplings of emissions, transport, and chemistry due to its simple design. Modules tested in the box model could be implemented in the 3-D model later on.