the university of reading helen dacre um user 2009 forecasting the transport of pollution using a...
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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 Analysis
Modis 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