forecasting the transport of pollution using a nwp model

The University of Reading Helen Dacre UM user 2009

Forecasting the transport of pollution using a NWP model

ETEX Surface Measurement Sites

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 Office’s NWP model in predicting tracer concentrations during ETEX 2

Aims

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

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

The University of Reading Helen Dacre UM user 2009

Synoptic AnalysisModis visible

08UTC 14/11/94 Frontal analysis at 00 UTC on

13th, 14th, 15th and 16/11/94

The University of Reading Helen Dacre UM user 2009

Precipitation Fields

Convective rain amount15/10/94 03 UTC

Large-scale rain amount15/10/94 03 UTC

The University of Reading Helen Dacre UM user 2009

Isentropic Surface Analysis

The University of Reading Helen Dacre UM user 2009

Horizontal Tracer Transport

15/11/94 03 UTC 16/11/94 03 UTC15/11/94 15 UTC

The University of Reading Helen Dacre UM user 2009

Vertical Tracer Transport15/11/94 03 UTC 16/11/94 03 UTC15/11/94 15 UTC

285K286K287K

288K

15/11/94 03 UTC 15/11/94 15 UTC

285K286K287K288K

16/11/94 03 UTC

285K

288K287K286K

15/11/94 15 UTC

15/11/94 15 UTCUM - no convectionUM

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

The University of Reading Helen Dacre UM user 2009

Wind Direction at Release Site

cold frontWin

d di

rect

ion

(deg

rees

)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