Air quality expert group - Fine particulate matter (PM2.5) in ... - Defra

µgm -3
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TIME SERIES OF DAILY AVERAGE OF PM2.5 2003 (HAR)
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TIME SERIES OF DAILY AVERAGE OF PM2.5 2003 (LBB)
FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
TIME SERIES OF DAILY AVERAGE OF PM2.5 2006 (HAR)
FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
TIME SERIES OF DAILY AVERAGE OF PM2.5 2006 (LNK)
FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
Figure A2.2.1: Time series of 24-hour means of PM2.5 concentrations for 2003
and 2006 from CMAQ and measurements from Harwell (HAR), London North
Kensington (LNK) and London Bloomsbury (LBB) stations. Red is observation and
blue is model results.
10. The underestimation of modelled results is observed for both stations in the
2006 run. However, the Harwell results shown in Table A2.2.1 for 2005 (January
and July) using the same model configuration, including meteorological fields
and grid resolution, but with year-specific emissions, indicate closer agreement
with measurements as indicated by the factor of 2 statistical metric (FACT2). A
full year run for 2005 is being planned and will lead to more insight into the
model performance. Specifically, it is recommended that sensitivity of PM2.5
concentration to boundary conditions and the long-term year-to-year variations
over multiple years be investigated to provide confidence in the performance
of models such as CMAQ to address policy issues. Scatter plots are shown for
2006 (Figure A2.2.2) and for January and July 2005 (Figure A2.2.3).
Model
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PM2.5 2006 (HAR)
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Annex 2: PM modelling in the UK
PM2.5 2006 (LNK)
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Figure A2.2.2: Scatter plots of 24-hour means of PM2.5 concentrations for Harwell
(HAR) and London North Kensington (LNK) for 2006. The red dashed line represents
1:1 line, the purple dashed line represents 2:1 line and the blue dashed line
represents 1:2 line.
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