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Traffic Restrictions Associated with the Sino-African Summit: Reductions of NOx

Detected from Space

Yuxuan Wang, Michael B. McElroy, K. Folkert BoersmaYuxuan Wang, Michael B. McElroy, K. Folkert BoersmaSchool of Engineering and Applied Sciences, Harvard UniversitySchool of Engineering and Applied Sciences, Harvard University

Henk J. Eskes, J. Pepijn VeefkindHenk J. Eskes, J. Pepijn Veefkind KNMI, De Bilt, The NetherlandsKNMI, De Bilt, The Netherlands

TEMIS Workshop, ESRIN, 8 Oct 2007

Forbidden City Downtown Traffic 6pm

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Chinese Emissions in the Global Context

Van der A et al., 2006

Jan 1996 Dec 2004

NO

2 co

lum

n d

ens

ity

Secular Trends of NO2 over China (TEMIS)

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Traffic Restrictions in Beijing during the Sino-African Summit: a natural experiment

Sino-African Summit: Nov 4 – 6, 2006Sino-African Summit: Nov 4 – 6, 2006 Purpose of traffic restrictions: to accommodate the Purpose of traffic restrictions: to accommodate the

meeting; dress-rehearsal for the 2008 Olympics meeting; dress-rehearsal for the 2008 Olympics GamesGames

Traffic Restrictions major initiativesTraffic Restrictions major initiatives Bans on government vehicles (490,000 vehicles Bans on government vehicles (490,000 vehicles

kept in garage)kept in garage) Increased capacity in public transportationIncreased capacity in public transportation Road restrictionsRoad restrictions call on private driverscall on private drivers

Public News: 30% reduction in on-road vehicles Public News: 30% reduction in on-road vehicles (800,000 out of 3 million)(800,000 out of 3 million)

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Questions Addressed in this Study:

1)1) Can we see the impact on the Can we see the impact on the atmosphere in the atmosphere in the near-real-timenear-real-time fashion?fashion?

2) How big was the impact using the 2) How big was the impact using the “top-down” constraints? Is it “top-down” constraints? Is it consistent with the bottom-up consistent with the bottom-up estimate?estimate?

The immediate, global, monitoring capability of NO2 made available through www.TEMIS.nl

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Measuring NO2 from Space

1995-200140 x 320 km2 footprint

global coverage: 3 days

GOME

2004-present13 x 24 km2 footprint

global coverage: 1 day

OMI

SBUV instruments in low Earth orbit

Climatological seasonal variability of NOx sources

near-real-time monitoring of local situations

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Ozone Monitoring Instrument (OMI) Dutch-Finnish made; aboard NASA EOS Aura Dutch-Finnish made; aboard NASA EOS Aura

satellitesatellite Nadir-viewing instrument measuring direct and

atmosphere-backscattered sunlight from 270 – 500 nm (NO2, SO2, O3)

equator crossing time 0145 and 1345: equator crossing time 0145 and 1345: (Beijing crossing time 1-3pm)(Beijing crossing time 1-3pm)

Wide field of view (2600 km) global coverage in one day

Small pixel sizes (Small pixel sizes (13 x 24 km13 x 24 km22 in the nadir ) in the nadir ) Near-real-time monitoring capability made Near-real-time monitoring capability made

available through available through www.temis.nlwww.temis.nl

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Ozone Monitoring Instrument (OMI) Dutch-Finnish made; aboard NASA EOS Aura Dutch-Finnish made; aboard NASA EOS Aura

satellitesatellite Nadir-viewing instrument measuring direct and

atmosphere-backscattered sunlight from 270 – 500 nm (NO2, SO2, O3)

equator crossing time 0145 and 1345: equator crossing time 0145 and 1345: (Beijing crossing time 1-3pm)(Beijing crossing time 1-3pm)

Wide field of view (2600 km) global coverage in one day

Small pixel sizes (Small pixel sizes (13 x 24 km13 x 24 km22 in the nadir ) in the nadir ) Near-real-time monitoring capability made Near-real-time monitoring capability made

available through available through www.temis.nlwww.temis.nl

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Day-to-day Variability in OMI NO2

Apparent decrease in NOApparent decrease in NO22 over Beijing during the over Beijing during the SummitSummit Some variations not driven by emission changesSome variations not driven by emission changes Need a chemical transport model to interpret the OMI Need a chemical transport model to interpret the OMI observationsobservations.

Before Summit during Summit after Summit

Oct. 29 Nov. 5 Nov. 7

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The GEOS-Chem Model1.1. Global chemical transport model; Global chemical transport model;

gas and aerosol chemistrygas and aerosol chemistry

2.2. Driven by time-specific, ‘realistic’, Driven by time-specific, ‘realistic’, assimilated meteorology from assimilated meteorology from NASA GMAONASA GMAO

3.3. 22o o (lat.) x 2.5(lat.) x 2.5oo (long.), full (long.), full representation of the whole representation of the whole troposphere troposphere

4.4. Extensively tested against Extensively tested against measurements (aircraft, surface, measurements (aircraft, surface, and satellite) inside and downwind and satellite) inside and downwind of China [of China [Wang et al.,Wang et al., 2004a; 2004a; 2004b; 2004b; Wang et al.,Wang et al., 2007a] 2007a]

5.5. Most recent national emission Most recent national emission inventory for China [inventory for China [Streets et al.,Streets et al., 2006; 2006; Zhang et al.,Zhang et al., 2007] 2007]

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OMI Observations and Model Comparisons

OMI (0.5ox0.5o) OMI (2ox2.5o)

model

The model has adequate ability in simulating the variationsThe model has adequate ability in simulating the variations

The decrease in NOThe decrease in NO22 over Beijing during the Summit not over Beijing during the Summit not

captured by the modelcaptured by the model

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OMI Observations and Model Comparisons

OMI (0.5ox0.5o)

model

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Consistent temporal variations at two scales

OMI NO2 (2ox2.5o)

OM

I N

O2

(0.5

ox0

.5o)

Model Scale (2ox2.5o)

Beijing Urban Area (40km x 40km)

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Model reproduces spatial patterns

NO2 columnNO2 / NOx ratio

NOx emis

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OMI-Derived Changes in Emissions

40% reduction !

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Meteorological conditions

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Summary1.1. Successful detection of reductions in NOSuccessful detection of reductions in NOxx from from

spacespace

2.2. GEOS-Chem model is able to reproduce day-to-GEOS-Chem model is able to reproduce day-to-day variations in NOday variations in NO22 columns (when without columns (when without dramatic changes in emissions)dramatic changes in emissions)

3.3. Vehicular emissions in BeijingVehicular emissions in Beijing Bottom-up method suggests 70% of total NOBottom-up method suggests 70% of total NOxx sources sources Our results: 40% reduction in total NOOur results: 40% reduction in total NOxx

50% reduction in vehicular sources50% reduction in vehicular sources Need to be tested by detailed energy consumption data Need to be tested by detailed energy consumption data

(i.e., gasoline sales)(i.e., gasoline sales)

4.4. Traffic restrictions were very effective in reducing Traffic restrictions were very effective in reducing emissions of NOemissions of NOxx in urban areas of Beijing. in urban areas of Beijing.

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The China Project at Harvard University

1.1. Reliable data on emissions Reliable data on emissions (bottom-up (bottom-up method)method)

2.2. A model assimilating meteorological data A model assimilating meteorological data with a comprehensive treatment of with a comprehensive treatment of chemistry chemistry (GEOS-Chem model and its (GEOS-Chem model and its nested-grid version)nested-grid version)

3.3. High quality data for key species providing High quality data for key species providing a meaningful test of the model a meaningful test of the model (ground (ground station, aircraft, and satellite)station, aircraft, and satellite)

http://chinaproject.harvard.edu/

Elements of its Atmospheric Science Program

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What have we benefited from TEMIS?

1.1. The Near-Real-Time data from OMIThe Near-Real-Time data from OMI

2.2. Stratospheric NOStratospheric NO22 columns assimilated from columns assimilated from

the GOME instrument [the GOME instrument [Wang et al.,Wang et al., 2007a] 2007a]

3.3. Easy data access and communication!Easy data access and communication!

TEMIS can be made even better…

1.1. The OMI data format (currently 0.3 GB The OMI data format (currently 0.3 GB for one day worth of data)for one day worth of data)

2.2. Customized on-line plotting capability Customized on-line plotting capability (user-defined color scale)(user-defined color scale)

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Future Directions using TEMIS Products

1.1. To obtain more quantitative constraints To obtain more quantitative constraints on emissions of NOon emissions of NOx x

2.2. The 2008 Summer Olympics and The 2008 Summer Olympics and anticipated improvement in air qualityanticipated improvement in air quality

3.3. Monitoring of SOMonitoring of SO22 emissions in China emissions in China

(acid rain and sulfate aerosols) using (acid rain and sulfate aerosols) using SCIAMACHY and OMI products. SCIAMACHY and OMI products.

4.4. Trans-boundary pollution transport Trans-boundary pollution transport (intra-Asia, Asia – U.S; Europe-Asia)(intra-Asia, Asia – U.S; Europe-Asia)

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Acknowledgement

1.1. Financial support from the National Financial support from the National Science Foundation, USAScience Foundation, USA

2.2. Pieternel Levelt and the OMI Science Pieternel Levelt and the OMI Science teamteam

3.3. Helpful discussions with Shuxiao Wang, Helpful discussions with Shuxiao Wang, Weihua Ge and Chen Dan at Tsinghua Weihua Ge and Chen Dan at Tsinghua University and Qiang Zhang at the University and Qiang Zhang at the Argonne National Lab.Argonne National Lab.

4. The TEMIS project and support4. The TEMIS project and support