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CMAS Conference 2011
Comparative analysis of CMAQ simulations of a particulate matter episode over Germany
Chapel Hill, October 26, 2011
V. Matthias, A. Aulinger, M. Quante, C. Chemel, J. L. Perez, R. San Jose, R. Sokhi
Volker Matthias, Oct 26, 2011 2
Case study on PM10 (Feb/March 2003)
Stern et al., Atm. Env. 42, 4567-4588 (2008)
PM10 daily mean concentration (µg/m3) over Germany on March 2, 2003
Volker Matthias, Oct 26, 2011 3
COST 728 study
COST 728:
European cooperation,
participants from more than
20 nations
„Enhancing Mesoscale
Meteorological Modelling
Capabilities for Air Pollution
and Dispersion Applications“
Volker Matthias, Oct 26, 2011 4
Group Met-Model CTM
IfK, HZG MM5 CMAQ
Uni Hertfordshire (UH) WRF CMAQ
TU Madrid (UPM) MM5 CMAQ
CMAQ model intercomparison
Volker Matthias, Oct 26, 2011 5
What are the differences?
Preparation of the emissions Meteorological fields Inital and boundary conditions Grids (horizontal and vertical structure) Computing platforms People who run the model
Volker Matthias, Oct 26, 2011 6
Concept
Round 1:
All groups provide input files (IC,BC,EMIS,METEO,GRIDDESC)
All groups use common CMAQ version (4.7) and chemistry mechanism (cb05_ae_aq)
All groups recalculate results of others
Expected results:
Determination of simple (model user) errors (switches …) Quantification of computing errors (compiler, platform, …)
Volker Matthias, Oct 26, 2011 7
Recalculations: Sulfate
Westerland
Melpitz
Volker Matthias, Oct 26, 2011 8
Westerland
Melpitz
Recalculations: Nitrate
Volker Matthias, Oct 26, 2011 9
Outcome: Recalculations
CMAQ model results can be reproduced by other groups on
different computing platforms
Depending on species, some differences exist but they are much
smaller than the differences in the “blind“ runs
Volker Matthias, Oct 26, 2011 10
Concept (2)
Round 2:
Agree on common grid
Use same initinal and boundary conditions (IC & BC)
Expected Results
• influence of emissions• influence of meteorological fields
Volker Matthias, Oct 26, 2011 11
Impact of emissions
Reconstruction of UH runEmission files from UPM
Sulfate Nitrate
Volker Matthias, Oct 26, 2011 12
Emissions in Central Europe (spatial average)
NO
SO2
NH3
UHUPMHZG
Time series from CMAQ input files
Volker Matthias, Oct 26, 2011 13
Outcome: Emissions
Emissions may be prepared in different ways concerning their
temporal and spatial variation.
For short time series at certain grid points this may lead to
significant differences in particle concentrations.
Volker Matthias, Oct 26, 2011 14
Impact of meteorology
MM5 from UPMMM5 from HZGWRF from UHS
Sulfate Nitrate
Volker Matthias, Oct 26, 2011 15
Outcome: Meteorology
Numerous meteorological parameters may influence particle
concentrations.
The quality of the CTM results may not be judged from the
quality of the meteorological fields.
Volker Matthias, Oct 26, 2011 16
Open questions
Do we see „typical“ differences between „correct“ model runs or
were there important errrors in the input data?
Sensitivity study:
Annual runs (year 2000) with CMAQ 4.6 with different Boundary conditions Emission files Meteorological data
Goal:
Quantify the variability of the hourly and daily concentrations at Melpitz
Volker Matthias, Oct 26, 2011 17
Boundary conditions
BC from global models: Mozart and TM4
SO2 SO4 NO3
Volker Matthias, Oct 26, 2011 18
Emissions
SMOKE-EU emissions and EMEP emissions
Additional comparisons to other emission data sets with similar results
SO2 SO4 NO3
Volker Matthias, Oct 26, 2011 19
Meteorology
MM5 (FDDA with NCEP) and CCLM (Spectral nudging with NCEP)Hourly values
SO2 SO4 NO3
Volker Matthias, Oct 26, 2011 20
CMAQ intercomparison: different emissions
Nitrate values with UH emissions lower than it could be expected.
SO4 NO3
Volker Matthias, Oct 26, 2011 21
CMAQ intercomparison: different meteorological fields
Sulfate values with UPM and HZG meteo within expected range
Nitrate values low, but may be explained by variability due to meteo input
SO4NO3
Volker Matthias, Oct 26, 2011 22
Summary
CMAQ intercomparison within COST 728 showed:
Simulations are reproducable by other groups on other computing platforms Emission data may be prepared in very different ways Largest influence on simulation results comes from meteorology Unreliable results may be detected by comparisons to sensitivity runs
AcknowledgementsEmission data has been prepared by Johannes Bieser
Most CMAQ sensitivity runs were set up by Johannes Bieser
Total gridded emissions were provided by TNO, IER and EMEP
Boundary conditions were provided by the RETRO project (TM4) and Ulrike Niemeier (Mozart)
Volker Matthias, Oct 26, 2011 23
Thank you