Chemical regimes over Europe – long term , seasonal and day to day variability
description
Transcript of Chemical regimes over Europe – long term , seasonal and day to day variability
Chemical regimes over Europe – long term , seasonal and day to day
variability
Matthias Beekmann
LISA University Paris 7 and 12, CNRS
Créteil, France
Thanks to Robert Vautard for discussions and MM5 data
Definitions
VOC sensitive regime:
• VOC emission reductions more favorable for ozone reduction
• Near intense anthropogenic emission sources
• Low VOC / NOx emission ratio
• Weak actinic flux
• Radical chain terminationNO2 + OH -> ….RCOO2 + NO2 -> …. RO2 + NO -> ….
NOx sensitive regime :
• NOx emission reductions more favorable for ozone reduction
• Rurales areas
• High VOC / NOx emission ratio
• Strong actinic flux
• Radical chain terminationHO2 + HO2 -> ….RO2 + HO2 -> ….
INTRODUCTION Environmental conditions
Chemical cycles
PLAN
Many older studies, but no comprehensive work addressing: • Differences in chemical regimes with respect to target
• Interannual, seasonal variability
• Day to day variability, which forcings ?
• Long term variability (decades)
• Dependency to model configuration
Developed by: IPSL, LISA /CNRS, INERIS [http://euler.lmd.polytechnique.fr/chimere]
Model domain : 10°W-23°E, 35°-58°N
Horizontal resolution : 0.5° x 0.5°
Vertical resolution: 8 layers in hybrid pressure coordinates
Pk=akptop + bkpsurf; ptop=500 mbar
Chemical mechanism: reduced MELCHIOR ( 44 species, 120 reactions)
here use of gas phase only
Meteorology: MM5 driven by NCEP Reanalysis or Forecast
Emissions: EMEP NOx,VOC, CO, SO2, 10 SNAP sectors; res. 50x50 km
Biogenic emissions of isoprene, pinene and NO
Boundary conditions: LMD-Z/INCA , MOZART , GOCART (PM)
CHIMERE CHEMISTRY-TRANSPORT MODEL
ResultsReference simulation
• Daily O3 maximum
• Surface = 0 – 50 m
• Average over • May – August• 2001
2002 2003
Results (2)Emission scenarii
Chemical Regime = NOx -30 % minus
VOC -30% emission scenario
Chemical Regime Emissions
Industrial NOx emissions 1010 mol. cm-2 s-1
=> Strong dependence of chem. regime on emission strength, modulated by meteorology
• Daily O3 max. => basic pollution indicator
• Daily OX max.OX = O3 + NO2
=> normalises out O3 titration by NO
• AOT60
hours max [O3 – 60 ppb, 0] => climatological health index
• AOT90
hours max [O3 – 90 ppb, 0]=> pollution peak indicator
• SUMO 35 days max [daily max O3
8h – 35 ppb, 0] => climatological health index
Chemical regimes for different targets
Chemical regimes for different targets
maximum daily OX concentration May – August 2001- 2003 average
Chemical regimes for different targets
SUMO35 May – August 2001 – 2003 integration/ average
Chemical regimes for different targets
AOT60 May – August 2001 – 2003 integration/ average
Chemical regimes for different targets
AOT90 May – August 2001 – 2003 integration/ average
Chemical regimes for different targetsConclusions
General structure keeps unchanged irrespective of target :
• NW EU VOC sensitive
• SE EU NOx sensitive• • North Italy NOx sensitive with exceptions
• Shipping track VOC sensitive
Are these model results robust ?
• Model has been evaluated with ozone measurements over Western Europe=> Small bias, RMSE ~ 20% , R ~ 80% over WE
• But no garantee, that sensitivity of PO3 to EVOC and ENOx is correct
• Ideal solution: Monte Carlo simulations => give global uncertainty
• Here sensitivity tests
* EVOC + 40 %
* other chemical mecanism: extended Melchior (~80 compounds, 320 reactions) instead of reduced one (40 compounds, ~120 reactions, operator approach)
* look at model layer 2 (50 – 200 m) instead of layer 1 (0-50m) => regions with complex vertical structure
Robustness test O3max
Many structures absent
Robustness test AOT90
Interannual variability O3max
Seasonal variability O3max
The heatwave caseAugust 2003
O3max AOT90
O3max and AOT90 : NOx sensitive regime more extended
Day to day variability of chemical regimesO3max
• Integration over the strongly VOC sensitive region in NW – Europe
• From May to August 2001
Day to day variability of chemical regimesO3max
Chemical regime is always VOC sensitive over North-Western Europe
No dependency on ozone levels
How can day to day variability be explained ?
Day to day variability of chemical regimesO3max
Dependence on emission accumulation (NOy)
Dependence on classical chemical regime tracersO3 / NOz ratio
O3 / NOz ratio
Chemical regime for 1980 – 2020 emissions
• Is the chemical regime expected to change for future emission scenarii ?
• Did it change in the past ?
=> Use EMEP 1980 , 1990, 2010 and 2020 expert emissions in addition to 2002 one’s
=> No change in boundary conditions , trends not clear
Chemical regime for 1980 – 2020 emissionsO3max
1980 1990
2010 2020
Chemical regime for 1980 – 2020 emissionsAOT90
Year
1980
Year 2020
Conclusions • Chemical regime is (in CHIMERE European CTM)
VOC sensitive over North Western Europe, NOx sensitive over Mediterranean region and Eastern Europe
• This is robust with respect to :* target
* model uncertainty* interannual, seasonal, day to day variability
• Northern Italy : NOx sensitive, with exceptions (Milan area, …. exceptions not so robust)
• Shipping emissions : VOC sensitive, but complex vertical structure
• 1980 to 2020 emission changes drive system to more NOx sensitive in NW EU, in North Italy