1. The University of Reading Helen Dacre AMS 2010 Air Quality Forecasting using a Numerical Weather Prediction Model ETEX Surface Measurement Sites

2. The University of Reading Helen Dacre AMS 2010 To determine the meteorological processes responsible for transporting tracer during ETEX 2 To assess the performance of the UK Met Offices NWP model in predicting pollution concentrations Aims

3. The University of Reading Helen Dacre AMS 2010 Talk Outline Overview of NWP model Analysis of meteorological processes Tracer transport in the UM –Horizontal –Vertical –Qualitative comparison with observations Potential sources of error

4. The University of Reading Helen Dacre AMS 2010 UK Met Office Unified Model Eulerian, non-hydrostatic NWP model Includes parameterisations (boundary layer mixing, microphysics, convection) Limited area model 12 km resolution Tracer released into lowest model grid box Tracers are passive LAM domain

5. The University of Reading Helen Dacre AMS 2010 Synoptic Analysis Modis visible 08UTC 14/11/94 Frontal analysis at 00 UTC on 13 th, 14 th, 15 th and 16/11/94

6. The University of Reading Helen Dacre AMS 2010 Precipitation Fields Convective rain amount 15/10/94 03 UTC Large-scale rain amount 15/10/94 03 UTC

7. The University of Reading Helen Dacre AMS 2010 Isentropic Surface Analysis

8. The University of Reading Helen Dacre AMS 2010 Horizontal Tracer Transport 15/11/94 03 UTC16/11/94 03 UTC15/11/94 15 UTC UM OBS

9. The University of Reading Helen Dacre AMS 2010 Vertical Tracer Transport 15/11/94 03 UTC16/11/94 03 UTC15/11/94 15 UTC 285K 286K 287K 288K 15/11/94 03 UTC15/11/94 15 UTC 285K 286K 287K 288K 16/11/94 03 UTC 285K 288K 287K 286K 15/11/94 15 UTC UM - no convection UM

10. The University of Reading Helen Dacre AMS 2010 Conclusions A warm conveyor belt transported tracer up to height of 4km and tracer was transported further to 8km by convection Potential sources of error: –M odel resolution –Representation of sub-grid scale processes –Choice of model dynamics –Meteorological forecast accuracy H. F. Dacre (2010). Evaluating the ability of a numerical weather prediction model to forecast tracer concentrations during ETEX 2, Atmos. Env., 44, 294-303.

11. The University of Reading Helen Dacre AMS 2010 Wind Direction at Release Site cold front Wind direction (degrees) 360 315 270 225 180 15 18 21 00 03 06 09 12 15 14/11/94 Time (UTC) 15/11/94 50km 12km Obs