© crown copyright met office impact of emission schemes on online air quality modelling wwosc –...

© Crown copyright Met Office

Impact of Emission Schemes on Online Air Quality ModellingWWOSC – Montreal – August 2014

Carlos Ordóñez, Mohit Dalvi, Nick Savage, Paul Agnew, Lucy Davis, Marie Tilbee


Impact of Emission Schemes on Online Air Quality Modelling

1. Introduction of AQUM

2. Representation of emissions in AQUM

3. Vertical and temporal profiles of emissions

4. Results

5. Summary and outlook


1. Introduction


Air Quality in the Unified Model (AQUM)

• Limited area configuration of the Unified Model (UM) used for AQ forecast

• 12 km horizontal resolution & 38 model levels (surface-39km)

• On-line model: chemistry & aerosol processes fully coupled to meteorology

• 5-day operational AQ forecast for the UK with:

• Meteorological LBCs from UM global run

• Chemical LBCs from MACC global forecast

• Also run in hindcast mode (chemical LBCs from MACC & GEMS reanalyses, …)


• Chemistry processes represented within the United Kingdom Chemistry and Aerosols (UKCA) sub-model of the UM.

• UKCA initially developed for climate-chemistry studies at the global scale. A number of chemistry schemes available.

• Regional Air Quality (RAQ) chemistry scheme implemented to introduce more complex reactive organic chemistry:

• oxidation of C4 alkanes (butane), C2-C3 alkenes (ethene and propene), and aromatic compounds (toluene and o-xylene)

• Main features of RAQ• Adapted from STOCHEM [Collins et al., 1997, 1999]• 40 transported species (16 emitted) + 18 non-advected• 116 gas-phase reactions + 23 photolysis reactions• Dry deposition for 16 species + wet dep. for 19 species

Chemistry and aerosol processes (I)


• CLASSIC aerosol scheme (another UM sub-model, not part of UKCA)

• SO2 & ammonium sulphate

• Ammonium nitrate• Black carbon• Fossil fuel organic carbon (FFOC)• Biomass burning aerosol• Climatology of biogenic secondary organic aerosols (BSOA)• Online emissions of dust & sea-salt

Calculation of PM2.5 & PM10 concs

• More details or RAQ chemistry and aerosol processes in AQUM: Savage et al. [GMD, 2013]

Chemistry and aerosol processes (II)

Coupled to UKCA oxidants

• Future: Use of GLOMAP-mode aerosol scheme. Full coupling between chemistry & aerosols in UKCA

• Details on CLASSIC & GLOMAP-mode: Bellouin et al. [JGR, 2011; ACP, 2013]


2. Representation of emissions in AQUM


Generation of emissions

NAEI @ 1km ENTEC shipping @ 5km EMEP @ 50km

(more recently 5 km MACC dataset, valid for 2003-2009)

Generated by merging all source sectors from datasetsat different resolution: NAEI, EMEP/MACC & ENTEC


Aerosol emissions (in CLASSIC)

• Combination of monthly 2-D (low-level and high-level) and 3-D fields• Online emissions of dust and sea-salt

See details in Savage et al. [GMD, 2013]

Emissions of gas phase species (in UKCA)

• Monthly varying emission files:• 2-D “surface” emissions of NOx, CO & 14 VOCs (inc. biog C5H8)• 3-D field for NOx from aircraft

• All anthropogenic source sectors merged

• Simplistic vertical profiles and temporal emission factors

Current treatment of emission in AQUM

UKCA and CLASSIC initially developed for climate-chemistry-aerosol studies at the global scale. The representation of emissions lacks the flexibility needed for regional AQ modelling.


• New emission system for gas phase emissions in UKCA:

• Independent monthly emission fields for each source sector

• They can be injected at different altitudes and with different temporal variability

• Aerosol emissions remain unchanged because CLASSIC will be retired. Future: extend the new system to aerosol emissions in UKCA.

New emission scheme


3. Vertical and temporal profiles of emissions


Three types of vertical profiles tested for antropogenic emissions:

• step1 (current system): Emissions injected in three lowest model levels: 80% (20 m mid-layer), 15% (80 m) & 5% (180 m)

• EMEP: Profiles based on those from EMEP model [Simpson et al., ACP, 2012]

• Bieser: Based on calculations with SMOKE-EU plume-rise model [Bieser et al., Env. Pollut., 2011]

Vertical disaggregation of emissions

Vertical disaggregation for SNAP sectors 1–10

Injection heights: EMEP > Bieser > step1


• traffic-UK (current system): Factors based on traffic UK data applied to

all anthropogenic emissions• TNO-MACC: Derived by TNO for the MACC project [Denier van der

Gon et al., 2011]

Temporal emission factors

Hourly factors

traffic-UK

non-traffic

Hourly & daily factors needed to account for daily and weekly variability in emissions. Implemented using two sources:


• traffic-UK (current system): Factors based on traffic UK data applied to

all anthropogenic emissions• TNO-MACC: Derived by TNO for the MACC project [Denier van der

Gon et al., 2011]

Temporal emission factors

Hourly & daily factors needed to account for daily and weekly variability in emissions. Implemented using two sources:

traffic-UKtraffic (TNO-MACC)

non-traffic (TNO-MACC)

Daily factors


4. Results


Summary of emission profiles tested

• Vertical profiles

EMEP, Bieser & step1 (EMEP & Bieser evaluated by Mailler et al. [ACP, 2013])

• Temporal factors• traffic-UK: unreasonable bimodal diurnal cycle• TNO-MACC: more realistic


Summary of emission profiles tested

Simulation Vertical profiles Time profiles

CTRL step1 traffic-UK

Bieser-TNO Bieser TNO-MACC

EMEP-TNO EMEP TNO-MACC

We show results (mainly summer 2006/2013) for:

operational

Comparison with AURN surface observations (> 50 sites)

effectiveemission

height

• Vertical profiles

EMEP, Bieser & step1 (EMEP & Bieser evaluated by Mailler et al. [ACP, 2013])

• Temporal factors• traffic-UK: unreasonable bimodal diurnal cycle• TNO-MACC: more realistic


NOx & O3 (June – July 2006)





LBCs from GEMS reanalysis







NOx & O3 (June – July 2006)

AURN observations (> 50 sites)






CTRL Bieser-TNO EMEP-TNO


O3 (June – July 2006)

FGE 0.35 0.33 0.32MNMB -0.03 -0.03 0.01R 0.70 0.73 0.73Stdev ratio 0.91 0.93 0.92fac2 0.86 0.88 0.89


O3 (operational: Jul – Aug 2013)


LBCs from MACC global forecast

MNMB 0.19 0.20 0.22R 0.65 0.67 0.67Stdev ratio 0.97 0.98 0.98fac2 0.86 0.87 0.87

FGE 0.36 0.35 0.36



Diurnal cycles of bias/RMSE (Jun–Jul 2006)

0 6 12 18 23

NO2NO

Bias(µg m-3)

0 6 12 18 23

0 6 12 18 23

RMSE (µg m-3)

0 6 12 18 23 0 6 12 18 23

O3

0 6 12 18 23


Weekly cycles of RMSE (µg m-3)

NO2NO O3


JJ2006

Mon Tue Wed Thu Fri Sat SunMon Tue Wed Thu Fri Sat Sun

JA2013

Mon Tue Wed Thu Fri Sat SunMon Tue Wed Thu Fri Sat SunMon Tue Wed Thu Fri Sat Sun

Mon Tue Wed Thu Fri Sat Sun


Minor impact on PM






5. Summary and outlook


Summary and outlook (I)

• A new emission scheme (initially only for gas phase species) implemented

• Flexibility:• Can handle emissions independently according to source sector• Allows the use of realistic vertical and temporal profiles

• Bieser vertical profiles and TNO-MACC temporal factors adopted for operational implementation in AQUM

• However minor impact on model results for NOx and O3

• Other processes in the model (e.g. chemical LBCs, dry

deposition, chemistry) may have a stronger impact on O3


Summary and outlook (II)

• CLASSIC aerosols GLOMAP-mode aerosols (UKCA). Extend new emission system for aerosols

• Interactive emission fluxes of biogenic VOCs from JULES (land surface model) in UKCA Impact on isoprene and O3

• Development of an AQUM configuration at 4 km x 4 km (70L) Test vertical emission profiles


Three types of vertical profiles tested for antropogenic emissions:

• Step1 (current system): Emissions injected in three lowest model levels: 80% (20 m mid-layer), 15% (80 m) & 5% (180 m)

• EMEP: Profiles based on those from EMEP model [Simpson et al., ACP, 2012]

• Bieser: Based on calculations with SMOKE-EU plume-rise model [Bieser et al., Env. Pollut., 2011]

Vertical disaggregation of emissions

Vertical disaggregation for SNAP sectors 1–10 Weighted avg. for NOx, CO and NMVOCs

Injection heights: EMEP > Bieser > step1


Operationally: LBCs from MACC global forecast at ECMWF

[Schere et al., AE, 2012]

CHIMEREObservations

Hindcast: LBCs from MACC & GEMS reanalyses

[Savage et al., GMD, 2013]

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