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

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CI – concentration (µg m -3 ) 5 4 3 2 1 0 Jan-08 Average measured vs modelled daily CI - concentration Feb-08 Mar-08 Apr-08 May-08 Jun-08 Jul-08 Aug-08 Sep-08 Oct-08 Nov-08 Dec-08 observed chloride modelled chloride Figure A2.3.4: Comparison between observed and modelled chloride (Cl - ) at three EMEP sites in Norwegian coastal areas. 24. This would suggest that the sea salt parameterisation in the model is reasonable and that in the UK a man-made source of Cl - is underestimated (consistent with Jones et al., 2010) or that deposition is overestimated. However, it is notable that the three Norwegian sites were located at a minimum of 190 m above sea level and in very remote areas. Given that there is likely to be a vertical concentration profile of sea salt it would seem reasonable to assume that the sea salt estimates for the UK could also be too small, however this would need further investigation. PM10 sulphate 25. For daily PM10 SO4 2- , the model predicted the non-episode concentrations of the observations well at Harwell and London North Kensington. However, the model was unable to capture peak SO4 2- at both sites, leading to a difference between modelled and observed annual average concentrations of approximately 1 µg m -3 or 49%. Figure A2.3.5 shows model versus measured daily PM10 SO4 2- concentrations at London North Kensington, where in April a long period of high SO4 2- concentrations was detected. -2 concentration (µg m -3 ) SO 4 20 15 10 5 0 N Kensington Annex 2: PM modelling in the UK observed sulphate modelled sulphate Jan-08 Feb-08 Mar-08 Apr-08 May-08 Jun-08 Jul-08 Aug-08 Sep-08 Oct-08 Nov-08 Dec-08 Figure A2.3.5: Time series of measures and CMAQ daily SO4 2- at London North Kensington, 2008. 157
PM2.5 in the UK 158 26. This was investigated using a trajectory model and OpenAir to define the possible source of SO4 2- during the period (Carslaw, 2011). The trajectories were three-hourly and were coloured according to the measured SO4 2- concentration (assumed to be constant for each hour of the day) (see Figure A2.3.6). A preliminary inspection of the trajectories and emission inventories suggests a potentially significant contribution from ships. Furthermore, comparison between TNO and EMEP emissions estimates show that for ships, SO2 emission rates can differ by up to a factor of two. The combination of errors in model trajectory estimates, emissions sensitivity tests and further data mining should provide an important insight into these periods of high PM concentrations and the role of shipping emissions. Figure A2.3.6: Trajectory of observed daily SO4 2- in April 2008. PM10 elemental carbon 27. The daily analysis of EC predictions for the final five months of 2008 indicates that the model underpredicts observed EC at London North Kensington in 2008, giving an average concentration of 0.44 µg m -3 compared with a measurement of 1.5 µg m -3 . There are a number of possible reasons for this, including underestimation of the contribution that EC makes to overall PM10 emissions. For road traffic in particular, and other sources in general, a more comprehensive calculation of the emission of EC (and primary organic carbon (POC)) should be made as part of future model runs. Estimating POC and SOC from OC measurements 28. Prior to comparing the CMAQ predictions of POC and secondary organic carbon (SOC), it was necessary to split the measurement of OC into primary and secondary components. To do this we used the EC tracer approach described in Jones and Harrison (2006), giving average estimates of observed POC and SOC at London North Kensington of 1.9 and 1.3 µg m -3 respectively.
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AIR QUALITY EXPERT GROUP Fine Parti
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This is a report from the Air Quali
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II Membership Chair Professor Paul
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IV Acknowledgements The Air Quality
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VI 2.5 Summary 39 2.5.1 What does t
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VIII 5.4 Components of PM2.5 and so
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PM2.5 in the UK 2 Air Quality Direc
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PM2.5 in the UK 4 I.2.1 Concentrati
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PM2.5 in the UK 6 • PM2.5 emissio
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PM2.5 in the UK 8 I.4.1 Modelling r
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PM2.5 in the UK 10 4. In broad term
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PM2.5 in the UK Table 1.2: National
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PM2.5 in the UK 14 17. Dry depositi
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PM2.5 in the UK 16 in ozone in the
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PM2.5 in the UK 18
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PM2.5 in the UK 20 5. The exact for
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PM2.5 in the UK 22 12. These diffic
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PM2.5 in the UK 24 2.3 Methods used
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PM2.5 in the UK 26 (e) During the
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PM2.5 in the UK 28 2.3.3 The Partis
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PM2.5 in the UK 30 35. For non-auto
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PM2.5 in the UK 32 43. Ratification
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PM2.5 in the UK 34 49. Many of the
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PM2.5 in the UK 36 57. Black carbon
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PM2.5 in the UK 38 2.4.4 PM2.5 elem
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PM2.5 in the UK 40 average of 93.6%
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PM2.5 in the UK Annex 1 - PM2.5 mon
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PM2.5 in the UK 44
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PM2.5 in the UK 46 3.2.1 Diurnal va
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PM2.5 in the UK 48 PM2.5/µgm -3 20
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PM2.5 in the UK 50 3.2.4 Seasonal v
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PM2.5 in the UK 52 12. Results are
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PM2.5 in the UK 54 3.4.2 Relationsh
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PM2.5 in the UK 56 Correlation 0.8
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PM2.5 in the UK Figure 3.11: Polar
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PM2.5 in the UK 60 south. Further a
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PM2.5 in the UK 62 3.7 PM2.5 episod
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PM2.5 in the UK 64 secondary ammoni
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PM2.5 in the UK 66 3.8 PM2.5 concen
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PM2.5 in the UK 68 3.9 Composition
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PM2.5 in the UK 70 43. The UK has i
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PM2.5 in the UK 72 NO 3 6 4 2 2000
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PM2.5 in the UK 74 54. PM ammonium
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PM2.5 in the UK 76 58. Data from th
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PM2.5 in the UK 78 (k) Road traffic
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PM2.5 in the UK 80 provided by spec
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PM2.5 in the UK 82 14. The London L
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PM2.5 in the UK Table 4.1: UK emiss
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PM2.5 in the UK 86 24. National inv
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PM2.5 in the UK 88 Figure 4.5: Spat
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PM2.5 in the UK 90 either nanoparti
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PM2.5 in the UK 92 37. Further cons
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PM2.5 in the UK Emissions (ktonnes)
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PM2.5 in the UK 96 Figure 4.7: Spat
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PM2.5 in the UK 98 4.4 A critical a
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PM2.5 in the UK 100 60. At a local
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PM2.5 in the UK 102 measurements an
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PM2.5 in the UK 104 4.5.2 Quantifyi
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Page 119 and 120: PM2.5 in the UK 108 4.6.1 Receptor
Page 121 and 122: PM2.5 in the UK 110 is predicated o
Page 123 and 124: PM2.5 in the UK 112 PM2.5 contribut
Page 125 and 126: PM2.5 in the UK 114 inorganic parti
Page 127 and 128: PM2.5 in the UK 116 93. While there
Page 129 and 130: PM2.5 in the UK 118 100% 90% 80% 70
Page 131 and 132: PM2.5 in the UK 120 105. Receptor m
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Page 135 and 136: PM2.5 in the UK 124 5. At the regio
Page 137 and 138: PM2.5 in the UK 126 15. Some of the
Page 139 and 140: PM2.5 in the UK 128 Figure 5.2: Tot
Page 141 and 142: PM2.5 in the UK 130 µgm -3 160 140
Page 143 and 144: PM2.5 in the UK 132 PM component (
Page 145 and 146: PM2.5 in the UK 134 with larger dev
Page 147 and 148: PM2.5 in the UK 136 Figure 5.8: UKI
Page 149 and 150: PM2.5 in the UK Figure 5.9: Compari
Page 151 and 152: PM2.5 in the UK 140 PM2.5 concentra
Page 153 and 154: PM2.5 in the UK 142 the North Sea (
Page 155 and 156: PM2.5 in the UK 144 53. Modelling r
Page 157 and 158: PM2.5 in the UK Annex 2: PM modelli
Page 159 and 160: PM2.5 in the UK 148 2. Figure A2.1.
Page 161 and 162: PM2.5 in the UK 150 6. The non-line
Page 163 and 164: PM2.5 in the UK 152 Model 50 45 40
Page 165 and 166: PM2.5 in the UK 154 (a) (b) modPM 2
Page 167: PM2.5 in the UK 156 NO3 - concentra
Page 171 and 172: PM2.5 in the UK 160 SIA components
Page 173 and 174: PM2.5 in the UK 162 x 50 km grid fo
Page 175 and 176: PM2.5 in the UK 164 A2.6: Photochem
Page 177 and 178: PM2.5 in the UK 166 PM2.5 Emission
Page 179 and 180: PM2.5 in the UK 168 A2.8: PCM PM mo
Page 181 and 182: PM2.5 in the UK 170 illustrated by
Page 183 and 184: PM2.5 in the UK 172 trajectory mode
Page 187 and 188: PM2.5 in the UK 176 4. The delivery
Page 189 and 190: PM2.5 in the UK 178 12. With respec
Page 193 and 194: PM2.5 in the UK Chapter 2: Measurin
Page 195 and 196: PM2.5 in the UK RoTAP (2012). Revie
Page 197 and 198: PM2.5 in the UK Harrison R.M. and Y
Page 199 and 200: PM2.5 in the UK Chapter 5 Modelling
Page 201 and 202: PM2.5 in the UK Jones A.M., Harriso
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