Meteorological Years for NEC Directive Review

1. Meteorological years available for use in IAM for the review of the NEC Directive Leonor Tarrasón, Anna Benedictow, Rasmus Benestad, Jan Eiof Jonson, Inger Hanssen-Bauer (met.no) Joakim Langner, Camilla Andersson and Robert Bergström (SMHI) 6th TFMM , 4-7th April , Zagreb, Croatia

2. Meteorological years that will be available for use under the revision of the NEC Directive The years 1996, 1997, 1998, 2000 and 2003 have been selected on the basis of • their availability for modelling • their climatological representativity over the last 30 years and • the feasibility of certain meteorological situations in future years 2020-2030. The final decision on which years and how they will used in IAM is to be considered later with CAFE SG

3. Meteorological variability of different air quality indicators 5%< SOMO35 < 10 % Mean O3 < 5% 10%< PM2.5 < 20 % Dep oxN < 20 % Changes due to meteorology alone are comparable to expected changes due to emission controls in 2010-2020

4. SOMO35 variability in the last 9-years Unified EMEP model calculations with constant emissions and 9 different meteorological years. Units: (10, 20, 35 %)

5. PM2.5 variability in the last 9-years Unified EMEP model calculations with constant emissions and 9 different meteorological years. Units: (10, 20, 35%)

6. Mean summer ozone variability in the last 30 years NEPAP project – MATCH model calculatios with 1970-2003 ERA40 data (%)

7. 4-year averages 1996, 1997, 1998, 2000 The 4-year average is closer to the last decades average than any individual year

8. 2003 extreme year for air quality Significant temperature anomalies PM2.5 SOMO35 Temperature The temperature anomaly is about 1-1,5ºC over Europe with large locally amplified temperature anomalies in certain areas

9. Plausible meteorological conditions in 2020-2030 Mean annual surface temperature Increase by 1-2ºC Climate model ECHAM4/OPYC3 results using IS92 scenarios in Norway <2020-2040> - <1980-1999> Increase by 1-1,5ºC Climate model GDFL results using SRES A2 greenhouse gas emission scenarios <2020-2030> - <1980-1999>

10. Future meteorological conditions Increased probability of occurrence of extreme years Observed monthly and seasonal summer temperatures in Swiss stations for 1864-2003. Climate model estimates for the same Swiss area for current (CTRL) and future conditions 2071-2100 (SCEN) By the end of this century, about every second summer could be as warm and dry in Central Europe as 2003 (Schär et al., 2004)

11. Choice of meteorological years available for the revision of NECD 1996: Characterised by cold weather situations in northern and western Europe. Relatively low ozone levels, higher PM2.5 levels. 1997: Generally close to the latest 8-year average weather conditions for most air quality indicators. 1998: Generally close to the latest 8-year average weather conditions for most air quality indicators, specially ozone. 2000: Reference base year for CAFE. Allows validation of results. Charaterised by warm weather conditions in northern and western Europe. Complementary to 1996 2003: Extreme warm and dry year in central and Southern Europe. Can be more probable in the next 20-30 years. THE <1996 –98, 2000> AVERAGE IS CLOSER TO THE LAST DECADES MEAN METEOROLOGICAL CONDITIONS THAN ANY OF THE INDIVIDUAL YEARS