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The University of Reading Helen Dacre AMS 2010
Air Quality Forecasting using a Numerical Weather Prediction Model
ETEX Surface Measurement Sites
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 Office’s NWP model in predicting pollution concentrations
Aims
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
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
The University of Reading Helen Dacre AMS 2010
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 AMS 2010
Precipitation Fields
Convective rain amount15/10/94 03 UTC
Large-scale rain amount15/10/94 03 UTC
The University of Reading Helen Dacre AMS 2010
Isentropic Surface Analysis
The University of Reading Helen Dacre AMS 2010
Horizontal Tracer Transport
15/11/94 03 UTC 16/11/94 03 UTC15/11/94 15 UTC
UM
OBS
The University of Reading Helen Dacre AMS 2010
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 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:
– Model 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.
The University of Reading Helen Dacre AMS 2010
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
