aerosol.modelling.aspects:.update. … observations&at&background& airbase...

Chemistry–aerosol coupling challenges in the CAMS global modelling system

Atmosphere Monitoring

Copernicus EU

Copernicus EU www.copernicus.eu

Copernicus EU

Samuel Rémy1, Olivier Boucher1, JeronimoEscribano1, Pierre Nabat2, Martine Michou2, Graham Mann3, Michael Schulz4, Zak Kipling5 and Johannes Flemming51 CNRS-‐IPSL 2 Météo-‐France 3 University of Leeds 4 Met.Norway 5 ECMWF

Aerosol modelling aspects: update and some results of the past yearCAMS43 contribution to Copernicus

AtmosphereMonitoring

Preamble

Xenophon, Greek general and writer, 5th century BC:“Fast is fine, but accuracy is everything.”


Outline

Updates of C-‐IFS (global atmospheric composition model used in CAMS) presented in this talk and others:

• Primary aerosols (dust and sea-‐salt)• Secondary aerosols : nitrate and organics• Dry deposition (Johannes Flemming’s talk at 12:30)• A word on emissions• C-‐IFS GLOMAP updates

• Aerosol alert service (talk on Thursday 09:15)

• Summary -‐ conclusions


A new sea-‐salt scheme

• The current sea-‐salt scheme is the Monahan et al (1986) scheme: sea-‐salt emissions are a function of 10m wind speed power 3.41

• New sea-‐salt scheme: adapted from Grythe et al. (2014, ACP)– Emissions function of 10m wind speed power 3/3.5 depending on

particle size– Dependency of sea-‐salt aerosol emissions on SST: relatively more

emissions over warm oceans– Emissions are closer to latest estimates of SSA emissions (for

particles with a diameter <= 10 micron) : ~11Tg per year

C-‐IFS 2014 emissions of seasalt aerosol bin 1, 2, 3 with the Monahan (M86) and Grythe (G14) schemes.

M86 G14Seasalt bin1 0.022 0.033Seasalt bin2 1.928 1.462Seasalt bin3 2.344 36.37Total emissions for Dp <= 10 micron 2.73 13.61



• Sea-‐salt AOD is significantly larger with G14 than with M86 over most oceans, smaller over continents

• Yearly total AOD is closer to MODIS observations

2014 total AOD simulated by C-‐IFS: with M86 scheme (top left), G14 (top right). MODIS AOD (bottom).



• Comparison with relevant AERONET stations show a better agreement with the new scheme

• The impact on PM10 forecasts over Europe is also positive

2014 total AOD: AERONET observations (blue dots); C-‐IFS with M86 (green) and G14 (red). AERONET stations at the Samoa Islands (top) and in the Caribbean Islands (bottom).

Scores of PM10 (in μg/m3) simulated by C-‐IFS with M86 and G14 against observations at background airbase stations in 2014.

M86 G14Average 19.96 19.11bias -‐0.32 -‐1.17RMSE 7.27 7.06correlation 0.68 0.72


A new dust scheme: ongoing

• The current dust scheme is the Ginouxet al (2001) scheme using prescribed threshold lifting speed and bare soil fraction.

• New dust scheme described in Nabat et al (2015, ACP), based on the Marticorena and Bergametti (1995) saltation scheme and the Kok et al (2011) size distribution at emission. Sand and Clay fraction from SURFEX (Météo-‐France) are used.

Volume size distribution of emitted dust aerosols; observations and provided by Kok et al brittle

fragmentation theory (gray line). Plot from Kok et al (2011).



• Emissions of super coarse particles are increased by a factor 4 with the new scheme

• Total dust emissions increased from ~1300 Tg per year to ~4000 Tg per year

• Over Sahara, ~ 2200 Tg per year against ~870 Tg per year, closer to most recent estimate (~2900 Tg per year).

2014 dust AOD with C-‐IFS: old scheme (top) and new scheme (bottom)



• Emissions of super coarse particles are increased by a factor 4 with the new scheme

• Total dust emissions increased from ~1300 Tg per year to ~4000 Tg per year

• Positive impact on scores vs AERONET

2014 dust AOD with C-‐IFS: old scheme (top) and new scheme (bottom)

2014: Modified Normalized Mean Bias (MNMB) and Fractional Gross Error (FGE) of C-‐IFS simulatedAOD, reference (green), and new dust scheme (red) against global AERONET observations.


Introducing nitrate and ammonium aerosol

Implementation into C-‐IFS of the Hauglustaine et al (ACP, 2014) nitrate/ammonium scheme. Nitrate is represented by:

– Fine mode nitrate, produced by gas partitioning:– Coarse mode nitrate, produced by heterogeneous reactions of HNO3

over calcite (dust) and sea-‐salt particles:

Global budgets of nitrate for C-‐IFS (2014), INCA (Hauglustaine et al original scheme) .

Process NO3 fine – ref(2000)

NO3 coarse –ref (2000)

NO3 fine C-‐IFS

NO3 coarseC-‐IFS

Chemicalproduction

0.27 0.93 0.18 1.03

Wet deposition 1.05 0.12 0.71Dry deposition 0.14 0.06 0.18Sedimentation 0 0 0.16Burden 0.05 0.13 0.018 0.108Lifetime 4.6 days 3 days 3.1 days



• Simulated nitrate surface concentrations are between 2 and 7 μg/m3 over heavily populatedareas.

• Values are generally overestimatedas compared to EMEP and AIRBASE observations.

C-‐IFS, 2014: Surface concentration of fine (top) and coarse (middle) mode nitrate. Bottom:

nitrate AOD.



• Comparison of C-‐IFS AODs with AERONET observations over Europe show better agreement with the nitrate scheme

• The impact on PM10 forecasts over Europe is positive for correlation

Modified Normalized Mean Bias (MNMB) and Fractional Gross Error (FGE) of C-‐IFS simulated AOD with (red) and without (green)

nitrates for 2014 against AERONET european observations.

Scores of PM10 (in μg/m3) simulated by C-‐IFS without nitrates on, with nitrates, and with nitrates and new sea-‐salt scheme.

Reference With nitrates Nitrates andnew sea-‐saltscheme

Average 19.96 24.81 24.13Bias -‐0.3 4.51 3.85RMS 7.25 9.07 8.55Correlation 0.68 0.72 0.75


Secondary Organic Aersosols (SOA)

• Part of the OM specie• Replaced the Dentener et al (2006) dataset

with production scaled on non-‐biomass burning CO emissions

• Better representation of the anthropogenic impact on SOA production

• Increases SOA production from ~20 Tg per year to ~140 Tg per year, closer to most recent estimates (Spracklen et al. 2011; Lin et al . 2012).

July: old (top) and new (bottom) SOA production flux in kg/(m².s)


Secondary Organic Aersosols (SOA)

• Part of the OM species• Replaced the Dentener et al (2006) dataset

with production scaled on non-‐biomass burning CO emissions

• Better representation of the anthropogenic impact on SOA production

• Increases SOA production from ~20 Tg per year to ~140 Tg per year, closer to most recent estimates (Spracklen et al. 2011; Lin et al . 2012).

MNMB of C-‐IFS simulated AOD for 2014 against AERONET obser vations, with older (red) and newer (green) SOA

production.


A word on emissions

• Use of MACCity emissions for– Non biomass burning OM and BC– SO2

• Better seasonality; yearly trend• Positive impact on scores vs AERONET,

except in July-‐August

MNMB, FGE and correlation of C-‐IFS simulated AOD for 2014 againstAERONET obser vations, with older (red) and newer (gray) emissions.

The green run is with newer emissions and the new SOA scheme


C-‐IFS GLOMAP: towards a pre-‐operational version• Optimization of the code: runtime divided by 5• Development of new components from CIFS-‐AER:

– New dust emission scheme, – New sea-‐salt emission scheme,– Sedimentation,– Secondary Organics scaled on CO emissions,– Use of MACCity emissions,– Nitrates (not finalized),– Integration of a new GLOMAP codebase that includes a stratospheric

aerosol capacity.• Scores of CIFS-‐GLOMAP vs AERONET are now comparable to those of

cycle 40R2 of CIFS-‐AER (2 years ago).


Summary -‐ conclusions

• The new developments presented here led to a significant improvement of the model skill as measured against AERONET and MODIS AOD

• In C-‐IFS, the aerosol and chemical components were developed and integrated separately

• The general direction of developments in C-‐IFS is towards a more coupled approach

• All of these developments have been made available or will shortly be made available in the version of C-‐IFS that is run operationally in the CAMS project

• However, what is switched on in the operational CAMS framework is not yet decided

19-‐05-‐17 17

2010: MNMB, FGE and temporal correlation of C-‐IFS simulatedAOD, reference (green), and with new developments except the new dust scheme (red) against global AERONET observations.


Online dry deposition velocities• Use of fixed deposition velocities for each

specie and over land/sea/ice

• Implementation and adaptation of a scheme (Zhang et al 2001) that computes online dry deposition velocities, depending on:– Particle size– Friction velocity– Roughness length

• Important diurnal and seasonal cycle of dry deposition velocities

June 2014: dry deposition velocities for sea-‐saltbin 1 (top), 2 (middle) and 3 (bottom), in m/s.


Online dry deposition velocities

• Comparison of C-‐IFS AODs with AERONET observations show better agreement with the new scheme

• The impact on PM10 forecasts over Europe is positive for most stations

2014: Modified Normalized Mean Bias (MNMB) and FractionalGross Error (FGE) of C-‐IFS simulated AOD, reference (green), and new dry dep scheme (red) against global AERONET observations.

2014; monthly PM10 (in μg/m3) simulated by C-‐IFS; reference(red) and new dry deposition (blue) at the Airbase Zwevegem

station, Belgium. Observations are in black.

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