1. The University of Reading Helen Dacre UM user 2009 Forecasting the transport of pollution using a NWP model ETEX Surface Measurement Sites

2. The University of Reading Helen Dacre UM user 2009 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 tracer concentrations during ETEX 2 Aims

3. The University of Reading Helen Dacre UM user 2009 Talk Outline Overview of NWP model Analysis of meteorological processes Tracer transport in the UM –Horizontal –Vertical Conclusions

4. The University of Reading Helen Dacre UM user 2009 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 UM user 2009 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 UM user 2009 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 UM user 2009 Isentropic Surface Analysis

8. The University of Reading Helen Dacre UM user 2009 Horizontal Tracer Transport 15/11/94 03 UTC16/11/94 03 UTC15/11/94 15 UTC

9. The University of Reading Helen Dacre UM user 2009 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 UM user 2009 Conclusions A warm conveyor belt transported tracer up to height of 4km and tracer was transported further to 8km by convection High resolution simulations needed to predict the change in wind direction and hence the observed tracer distribution The representation of sub-grid scale processes in NWP models can affect the distribution of tracer Accuracy of forecast is also sensitive to choice of model dynamics and accuracy of the meteorological forecast

11. The University of Reading Helen Dacre UM user 2009 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