Summer Heatwave 2006 – Ozone Pollution Episode

Jaume Targa Paul Willis

16/05/2007 Contents

• Introduction

• Defining the episode

• Weather Conditions

• AQ Monitoring

• Reasons for Episode

• Episode across

• Conclusions Introduction

• Elevated ozone levels are usually observed during periods with sustained high temperatures and sunshine levels

• Photochemical reactions in the atmosphere that produce ozone are favoured by such conditions

• High temperatures, coupled with the re-circulation of air masses over Europe and the UK are often conducive to ozone pollution episodes Introduction

• HIGH levels of air pollution were measured across the Automatic Urban and Rural Network (AURN) during June and July 2006.

• The AURN recorded ozone levels in Defra index 8 HIGH band (240-299 µgm -3) at three stations: − Wicken Fen, − London Haringey and − Blackpool Marton.

• The 3rd Daughter Directive (Directive 2002/3/EC) on ozone in ambient air has established an alert threshold of 240 µgm -3 as an hourly average over three consecutive hours. This alert threshold was exceeded at Wicken Fen on 19th July, when 8 consecutive hours were measured above 240 mgm-3. Defining the episode

300 Moderate Ozone Levels 275 High Ozone Levels EC Alert Threshold* )

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0 01/06/06 02/06/06 03/06/06 04/06/06 05/06/06 06/06/06 07/06/06 08/06/06 09/06/06 10/06/06 11/06/06 12/06/06 13/06/06 14/06/06 15/06/06 16/06/06 17/06/06 18/06/06 19/06/06 20/06/06 21/06/06 22/06/06 23/06/06 24/06/06 25/06/06 26/06/06 27/06/06 28/06/06 29/06/06 30/06/06 01/07/06 02/07/06 03/07/06 04/07/06 05/07/06 06/07/06 07/07/06 08/07/06 09/07/06 10/07/06 11/07/06 12/07/06 13/07/06 14/07/06 15/07/06 16/07/06 17/07/06 18/07/06 19/07/06 20/07/06 21/07/06 22/07/06 23/07/06 24/07/06 25/07/06 26/07/06 27/07/06 28/07/06 29/07/06 30/07/06 31/07/06 Days between June-July 2006 Defining the episode

• The geographical extend of monitoring stations measuring high levels across England and Wales. Sixty stations in the AURN recorded HIGH levels of ozone between June and July 2006

Number of High Days Weather Conditions

• June and July were very warm and dry over England and Wales

• July was exceptionally hot, with recorded temperatures of 36 °C on 19th July setting a new UK July temperature record

June July A very warm, dry and sunny month across An exceptionally warm month . Many most areas. Mean temperatures generally 1- areas had their warmest July, with some 2°C above average . Rainfall ranging from areas also experiencing their warmest close to average across western Scotland, to month (using a real series back to 1914). exceptionally below average across the Sunshine was also exceptionally above Midlands. Sunshine levels well above average, with the sunniest areas compared average across southern England . to average over north-east England. Rainfall was generally below average, although there Central London recorded a maximum were some notable exceptions. temperature of 32.4 C on 12th . Wisley recorded a temperature of 36.5 Source: http://www.meto.gov.uk/climate/uk/2006/index.html °C on 19th July setting a new UK July temperature record. Air Quality Monitoring

Site Number of Days Max hourly ( µµµgm -3) Date of hourly max High Moderate concentration Wicken Fen 13 41 278 19/07/06 Southend-on-Sea 8 38 232 04/07/06 Stoke-on-Trent Centre 8 24 244 19/07/06 Preston 7 18 218 18/07/06 Aston Hill 6 26 220 19/07/06 Bournemouth 6 21 232 18/07/06 Leamington Spa 6 25 228 19/07/06 London Brent 6 28 222 01/07/06 London Haringey 6 25 246 19/07/06 Lullington Heath 6 29 238 18/07/06 Portsmouth 6 27 230 18/07/06 Blackpool Marton 5 25 240 18/07/06 Bristol St Paul's 5 14 202 19/07/06 London N. Kensington 5 28 204 26/07/06 London Teddington 5 32 206 19/07/06 Northampton 5 24 214 19/07/06 Bottesford 4 27 196 20/07/06 Exeter Roadside 4 12 210 18/07/06 London Harlington 4 28 206 19/07/06 St Osyth 4 33 206 19/07/06 Wigan Centre 4 19 190 18/07/06 Air Quality Monitoring – 20 years…

Year Site Country Site type Hourly Max Data µg m-3 Capture 1986 Harwell England RURAL 274 92.7 1987 Harwell England RURAL 214 82 1988 Yarner Wood England RURAL 218 94.7 1989 Lullington Heath England RURAL 272 95.7 1990 Lullington Heath England RURAL 322 89.8 1991 Yarner Wood England RURAL 252 98.4 1992 Great Dun Fell England REMOTE 282 98.4 1993 Stevenage England SUBURBAN 266 98.2 1994 Sibton England REMOTE 254 95.6 1995 Lullington Heath England RURAL 268 95.5 1996 Sibton England REMOTE 242 92.7 1997 Leamington Spa England URBAN BACKGROUND 232 95.8 1998 Rochester England RURAL 240 93.3 1999 Barnsley Gawber England URBAN BACKGROUND 248 95.6 2000 Barnsley Gawber England URBAN BACKGROUND 206 96.5 2001 Exeter Roadside England ROADSIDE 328 94.3 2002 Sibton England REMOTE 218 99.1 2003 Middlesbrough England URBAN INDUSTRIAL 280 94.9 2004 Sibton England REMOTE 212 96.3 2005 Portsmouth England URBAN BACKGROUND 204 99.2 2006 Wicken Fen England RURAL 278 99.3 Air Quality Monitoring

90 Index 8

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NumberAURNof O stationswith 0 01/06/2006 02/06/2006 03/06/2006 04/06/2006 05/06/2006 06/06/2006 07/06/2006 08/06/2006 09/06/2006 10/06/2006 11/06/2006 12/06/2006 13/06/2006 14/06/2006 15/06/2006 16/06/2006 17/06/2006 18/06/2006 19/06/2006 20/06/2006 21/06/2006 22/06/2006 23/06/2006 24/06/2006 25/06/2006 26/06/2006 27/06/2006 28/06/2006 29/06/2006 30/06/2006 01/07/2006 02/07/2006 03/07/2006 04/07/2006 05/07/2006 06/07/2006 07/07/2006 08/07/2006 09/07/2006 10/07/2006 11/07/2006 12/07/2006 13/07/2006 14/07/2006 15/07/2006 16/07/2006 17/07/2006 18/07/2006 19/07/2006 20/07/2006 21/07/2006 22/07/2006 23/07/2006 24/07/2006 25/07/2006 26/07/2006 27/07/2006 28/07/2006 29/07/2006 30/07/2006 31/07/2006 Period of measurements Air Quality Monitoring – local networks

• Ozone episode was measured in local networks like: − Herts & Beds Air Pollution Monitoring Network (HBAPMN) − London Air Quality Network (LAQN) − Kent Air Quality Monitoring Network (KAQMN) − Sussex Air • The highest hourly ozone concentration measured was 251 mgm-3 at Lodsworth (Sussex Air) on 18th

• The 3rd Daughter Directive (Directive 2002/3/EC) alert threshold of 240 mgm-3 was exceeded at this location on 18th July. Three consecutive hours were measured above 240 mgm-3 Air Quality Monitoring – local networks

320 Rye Rural 300 Lodsworth 280

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0 18/07/06 19/07/06 20/07/06 Hour between 18 th and 20 th of July Reasons for Ozone Episode

• Summer ozone episode over the UK are usually characterised by high temperatures and air masses re-circulating over northern Europe and the UK.

• The June and July 2006 ozone episodes are characterised by these two factors. Reasons for Ozone Episode - Temperature

• Temperatures across June and, especially, July were exceptionally high

• A temperature of 36.5 °C was measured on 19th July, setting a new UK July temperature record Reasons for Ozone Episode - Temperature

90 35 Index 8 Index 7 80 Index 6 30 Index 5 70

Index 4 C) o CET 25 60 levels moderate levels moderate 3 20 50

40 15 or above above or

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0 0 01/06/2006 03/06/2006 05/06/2006 07/06/2006 09/06/2006 11/06/2006 13/06/2006 15/06/2006 17/06/2006 19/06/2006 21/06/2006 23/06/2006 25/06/2006 27/06/2006 29/06/2006 01/07/2006 03/07/2006 05/07/2006 07/07/2006 09/07/2006 11/07/2006 13/07/2006 15/07/2006 17/07/2006 19/07/2006 21/07/2006 23/07/2006 25/07/2006 27/07/2006 29/07/2006 31/07/2006 Period of measurements Reasons for Ozone Episode – Re-circulation

• Despite the good agreement between high temperature and high ozone shown, the re-circulation of air masses over Europe and the UK need also to coincide.

• If high temperatures are not associated with air masses re- circulation, then the conditions do not always necessarily lead to high ozone levels.

• On the other hand, if periods characterised by re-circulation of air masses do not coincide with high temperatures, ozone levels often remain moderate. Reasons for Ozone Episode – Re-circulation

15/07/2006 16/07/2006 17/07/2006

18/07/2006 19/07/2006 20/07/2006 Ozone Episode across Europe

• The 2006 European arrived at the end of June in a number of European countries including the UK, , , , the , Luxemburg, , the and .

• In some countries, July 2006 was the warmest month since official measurements began.

• The highest temperatures were generally recorded on 19th July. Ozone Episode across Europe

Modis Satellite Image showing Temperature on 19 th July 2006 at 10:35 UTC Ozone Episode across Europe

Near real time provisional data Conclusions

• High summer temperatures, combined with recirculating air over Europe and the UK resulted in the first prolonged ozone episode of 2006 .

• The June/July episode was also measured across Europe in the Benelux, Germany, France, Czech Republic…

• High summer temperatures in July resulted in HIGH levels of ozone, due to re-circulation of air over Europe or the UK.

• The area affected by the June/July episode was limited to England and Wales. Conclusions

• Changes in temperature and airmass back trajectories brought the episode to an end as clean air arrived from the Atlantic

• The highest hourly average ozone concentration recording during the episode was 278 µgm -3 (index 8) on the 19th July at Wicken Fen at 18.00.

• 3rd Daughter Directive ozone alert threshold of 240 µgm -3 was exceeded at Wicken Fen on 19th July, when 8 consecutive hours were measured above 240 µgm -3 .

• This threshold was also exceeded at a non-AURN site, Lodsworth (Sussex Air) on 18th July. Thanks!

• More information on:

Targa, J (2006) Air Pollution Forecasting:OZONE POLLUTION EPISODE REPORT (JUNE-JULY 2006) in the Air Quality Archive!