1. Analysis of ozone data from AIRBASE: Weekday dependence and trends
Roel van Aalst
EIONET AQ / TFMM
Geneva, September 2001

2. Hourly ozone data in AIRBASE
COUNTRY RURAL BACKGR URBAN BACKGR OTHER TOTAL AT BE BG CH CZ DE DK EE ES FI FR GB GR HU IE IT LT LV NL NO PL PT SE SI SK

3. The "classical" weekend effect
Ozone
0,4
0,5
0,6
0,7
0,8
0,9 1
1,1
1,2
1,3
1,4 2 3 4 5 6 7 8
Saturday Sunday Monday Tuesday Wednesday Thursday Friday
Normalized concentration

4. The "classical" weekend effect
Nitrogen Dioxide
0,4
0,5
0,6
0,7
0,8
0,9 1
1,1
1,2
1,3
1,4 2 3 4 5 6 7 8
Saturday Sunday Monday Tuesday Wednesday Thursday Friday
Normalized concentration

5. Ozone and NO2 trends anticorrelate
Annual average increments; full year
dO3 = dNO r = 0.24 N = 73 p = 0.039 10 5
dO3
-10 -5 5 -5
-10
dNO2

6. Ozone and NO2 trends anticorrelate
Annual average increments; Summer h
dO3 = dNO r = N = 69 p = 0.007 10 5
dO3
-10 -5 5 -5
-10
dNO2

7. Linear trend analysis for Ozone

8. Seasonal variation removed

9. Average rural ozone trends are upward
Ozone; rural background stations; >5 years
average trend = 0.6 +
1.5 % / y 10 5
trend (%/y) 10 20 30 40 50 60 -5
-10

10. Ozone; rural background stations > 5 full years15 10 5
-15
-10 -5 5 10 15
trend (%/y)

11. Urban ozone trends are more positive
Ozone; urban background stations; >5 years
average trend = 1.8 +
1.9 % / y 10 5
trend (%/y) 10 20 30 40 50 60 -5
-10

12. Ozone trends background stations > 5 full years15 10
urban
rural 5
-15
-10 -5 5 10 15
trend (%/y)

13. High exceedances are going down

14. High exceedances are going down

15. Weekday dependence of exceedances
…can provide information concerning the effect of emission reductions on Ozone
NMVOC and NOx emissions are ca 30 % lower during weekend days than during working days

16. Weekday dependence of exceedances

17. Weekday dependence of exceedances

18. Many conclusions - but in any case:
….lots of interesting information in the data
….can be accessed via internet
AIRVIEW: