Asian Air Pollution Export and Asian Air Pollution Export and Aerosol-Regional Climate Aerosol-Regional Climate

InteractionsInteractions

Yang Zhang, Kai Wang, and Yao-Sheng Chen

Air Quality Forecasting LaboratoryDept. of Marine, Earth and Atmos. Sci., NC State Univ.,

Raleigh, NC

Presentation at the 7th Annual CMAS Conference, Chapel Hill, NC, October 6-8, 2008

Carey J. Jang and Sharon Phillips Office of Air Quality Planning and Standards, the U.S.

EPA, Research Triangle Park, NC

Presentation OutlinePresentation Outline

• Introduction Introduction • Case StudiesCase Studies

– Intercontinental Transport over Trans-PacificIntercontinental Transport over Trans-Pacific• Horizontal Flux AnalysisHorizontal Flux Analysis• Process AnalysisProcess Analysis• Impact of Asian Anthropogenic Emissions on US Air Impact of Asian Anthropogenic Emissions on US Air

QualityQuality– Regional Climate-Air Quality Interactions over Regional Climate-Air Quality Interactions over

East AsiaEast Asia• Direct FeedbacksDirect Feedbacks• Semi-direct FeedbacksSemi-direct Feedbacks• Indirect FeedbacksIndirect Feedbacks

• SummarySummary

Asia N. America Europe

Boundary layer

Free troposphere

lifting subsidence

Tropopause

“Direct”intercontinental

transport

Mixing

2 km

Intercontinental Transport: uplifting of PM to troposphere/subtropical jet stream

Source: Jacob et al., 2004

Mechanisms for Intercontinental Transport Between Northern Midlatitude Continents

boundary layer advection

Intercontinental Transport over Trans-Intercontinental Transport over Trans-PacificPacific

Modeling Tool

• U.S. EPA’s Models-3/Community Multiscale Air Quality (CMAQ) modeling system version 4.4

• 180×74 horizontal grid cells with 108-km horizontal grid spacing

• 16 layers (surface to ~16 km) Meteorology

• Mesoscale Model MM5 (V3.6) IC/BC

• GEOS-CHEM

Emission Inventory

-- North America

• U.S.: NEI (1999) Projected to 2001 & Biogenic EI System BEIS-3

• Canada: 1995 EI & BEIS-3

• Mexico: 1999 Big Bend Regional Aerosol and Visibility Observational (BRAVO) Study & BEIS-3

-- Asia/China

• Transport and Chemical Evolution over the Pacific (TRACE-P) and Aerosol Characterization Experiment over Asia (ACE-Asia) 2000 EI

Simulations• Baseline with PA: 01, 04, 07, and 10 in 2001• Sensitivity: zero Asian man-made emissions

Measurements• Surface:

• Met: NCDC, CASTNET, STN, SEARCH, NADP

• Chem: Japan, China, main US networks• Satellite: NO2 (GOME), CO (MOPITT), TOMS/SBUV TOR, AOD

(MODIS)

Performance Statistics (NMB, %) Performance Statistics (NMB, %) for Surface Predictionsfor Surface Predictions

U.S.

Mo

Max 1-hr O3 (ppb) Max 8-hr O3 (ppb) PM2.5 (g m-3)

AIRS CASTNET SEARCH AIRS CASTNET SEARCH IMPROVE STN SEARCH

Jan 3.2 -22.6 -12.2 11.3 -16.1 -5.7 155.8 22.3 23.5

Apr -7.3 -18.5 -15.7 -4.7 -13.8 -7.7 55.7 51.5 15.4

Jul -0.7 -12.1 4.3 6.2 -4.2 19.0 27.0 21.7 32.9

Oct -15.6 -26.4 -19.8 -11.6 -21.6 -11.4 51.5 11.7 16.0

MoMax 1-hr

O3 (ppb)SO2

(ppb)

NO2

(ppb)

PM10

(g m-3)

Jan -41.7 -63.3 -61.2 -55.8

Apr -9.36 9.80 -76.8 -83.6

Jul -23.3 163.9 -81.3 -59.0

Oct -20.7 93.7 -79.9 -85.6

MoCO

(ppb)

SO2

(ppb)

NO (ppb)

NO2

(ppb)

SPM (g m-3)

Jan -64.0 -43.5 -89.5 -54.5 -67.3

Apr -56.7 -25.5 -91.1 -60.7 -49.7

Jul -55.5 -47.5 -93.4 -57.9 -56.3

Oct -65.7 -6.3 -94.6 -58.6 -71.0

China Japan

Evaluation of Column Evaluation of Column PredictionsPredictions

Month AOD NO2 Column CO Column TOR

Jan -29.1 19.4 -8.4 8.9

Apr -35.4 -3.9 -11.0 -26.1

Jul -29.2 -28.3 – – -51.9

Oct -24.5 0.9 0.9 -30.9

Obs

Sim

NO2 TOR AOD

Performance Statistics (NMB, %)Performance Statistics (NMB, %)

O3

Layer 12 (~5 km) Layer 1 (surface)

NOx

PAN

HCHO

Horizontal Fluxes of Gaseous Species (Horizontal Fluxes of Gaseous Species (g mg m--

22ss-1-1))

8.4 m/s 3.1 m/s

PM2.5

SO42-

NO3-

Layer 12 (~5 km) Layer 1 (surface)

OC

Horizontal Fluxes of PM Species (Horizontal Fluxes of PM Species (g mg m-2-2ss-1-1))

8.4 m/s 3.1 m/s

X-Z Cross-Sections between 25-50 °N of X-Z Cross-Sections between 25-50 °N of Horizontal Fluxes of Gas/PMHorizontal Fluxes of Gas/PM2.52.5 Species ( Species (g mg m-2-2ss-1-1))

Gases PM

HCHO

O3

NOx

PAN

PM2.5

SO42-

NO3-

OC

Process Analysis-IPR, April, 2001Process Analysis-IPR, April, 2001

East Asia

Pacific Ocean

U.S.

O3 (Gmoles/day) PM2.5 (Ggrams/day)

Total Air Pollution Export From Asia and Into U.S.Total Air Pollution Export From Asia and Into U.S.

Species Export/Import1

April Spring

Baseline Sensitivity Difference2

(Baseline-Sensitivity)

ImportInto US

Liang et al. (1998)

O3

(Gmole day-1)

TotalExport_Asia 0.1 -3.4TotalExport_US 2.8 2.9 -0.11 0.39

NOx

(Gmoleday-1)

TotalExport_Asia 0.06 -0.01

TotalExport_US 0.09 0.09 -0.002 0.15

NOy

(Gmoleday-1)

TotalExport_Asia 0.5 -0.1

TotalExport_US 0.6 0.6 -0.01 0.35

PM2.5

(Ggramday-1)

TotalExport_Asia 60.1 -11.8

TotalExport_US 30.1 30.6 -0.51TotalExport_Asia-total export out of the PBL over Eastern Asia; TotalExport_US-total export out of the PBL over the U.S.2 Difference-net export/import due to the Asia anthropogenic emissions.

Enhancement of Gas and PMEnhancement of Gas and PM2.5 2.5 species in April 2001 due to species in April 2001 due to Asian Anthropogenic Emissions in the West (Red) and East Asian Anthropogenic Emissions in the West (Red) and East

(Blue) U.S.(Blue) U.S.

MM5/CMAQ vs. WRF/Chem and Aerosol Feedbacks over MM5/CMAQ vs. WRF/Chem and Aerosol Feedbacks over China China • Period: 1-31 Jan./Jul. 2005• Domain: 164 × 97 grid cells• Horizontal resolution: 36 km• Vertical resolution:

30 layers (up to 50 mb) • Emissions:

– U.S. EPA SED-JES– Sea salt: online calculation

• Meteorology IC and BC: – NCEP/NCAR Global Reanalysis

• Chemical IC and BC:– CMAQ

• Gas-phase chemistry:– CBM-Z

• Aerosol module:– MOSAIC

• Cloud chemistry module:– CMU

• Scenarios:– Met; Met+Gas;

Met+Gas+PM+Cld. Aq.

• Data for model evaluation:– China/NCDC: T, RH, WS, Precip, PM,

API– Japan (2078 sites): T, RH, WS, SO2, NO2, CO, O3,

PM– China (a few sites): PM2.5 and Air pollution

indices– MOPITT: CO – OMI: NO2

– TOMS: Tropospheric Ozone Residual (TOR)

– MODIS: AOD

Aerosol Direct Effects on Shortwave Radiation and Aerosol Direct Effects on Shortwave Radiation and PhotolysisPhotolysis

Direct Effects on NO2 Photolysis

PM2.5 Mass Absolute Difference

PM2.5 decreases shortwave radiation and NO2 photolysis over most East Asia in Jan/Jul

Direct Effects on Shortwave Radiation

Jul

Jan

Aerosol Semi-Direct Effects on PBL Aerosol Semi-Direct Effects on PBL MeteorologyMeteorology

PBL Height2-m Temperature

PM2.5 Mass Absolute Difference

PM2.5 slightly decreases 2-m temperature; PM2.5 decreases PBL height in larger area in Jul than in Jan

Jul

Jan

Aerosol Indirect Effects on CCN and Aerosol Indirect Effects on CCN and PrecipitationPrecipitation

CCN (S = 1%)Changes in

PrecipitationPM2.5 Mass

Higher CCN concentrations over larger areas in East Asia in JanDominancy of suppression of precipitation in East Asia in Jul

Jul

Jan

SummarySummary

• Major Trans-Pacific Transport MechanismsMajor Trans-Pacific Transport Mechanisms– Strongest export for OStrongest export for O33, PAN, HCHO, and NO, PAN, HCHO, and NO33

-- at 25-45º N in the LFT at 25-45º N in the LFT – Strong export for CO, OStrong export for CO, O33, PM, PM2.52.5, SO, SO44

2-2- at the mid-latitude in the PBL at the mid-latitude in the PBL

• Relative Importance of Atmospheric ProcessesRelative Importance of Atmospheric Processes– Transport, chemistry, and dry depo are important for OTransport, chemistry, and dry depo are important for O33

– Emissions, aerosol/cloud proc., and transport are important for PMEmissions, aerosol/cloud proc., and transport are important for PM2.52.5

• Impact of Asian Anthropogenic Emissions on US AQImpact of Asian Anthropogenic Emissions on US AQ– Total export: 0.1 Gmoles/day of OTotal export: 0.1 Gmoles/day of O33 and 0.5 Ggrams/day of PM and 0.5 Ggrams/day of PM2.52.5

– Increases background OIncreases background O33 in the WUS by ~1 ppb (~2.5%) in monthly in the WUS by ~1 ppb (~2.5%) in monthly average, and up to 2.5 ppb in daily averageaverage, and up to 2.5 ppb in daily average

– Increases background SOIncreases background SO442-2- in the WUS by 0.4 in the WUS by 0.4 g mg m-3-3 (~20%) in (~20%) in

monthly average, and up to 1.0 monthly average, and up to 1.0 g mg m-3-3 in daily average in daily average

• Aerosol Feedbacks to Regional ClimateAerosol Feedbacks to Regional Climate– PMPM2.52.5 decreases shortwave radiation and NO decreases shortwave radiation and NO22 photolysis photolysis– PMPM2.52.5 decreases 2-m temperature and PBL height decreases 2-m temperature and PBL height– PMPM2.52.5 enhances CCN formation and suppresses precipitation enhances CCN formation and suppresses precipitation

AcknowledgementsAcknowledgements U.S. Environmental Protection Agency (EPA)’s ICAP Project, NASA Award No. NNG04GJ90G and NSF Career award at NCSU Andreas Richter, the University of Bremen, Germany, for providing GOME NO2 data; Hilary E. Snell, AER Inc., for processing MOPITT CO and GOME NO2; Jack Fishman and John K. Creilson, NASA Langley Research Center, for providing TOR Alice Gilliland and Steve Howard, U.S. EPA, for providing observational data from national networks over U.S. and the Fortran code for extracting data from observations and CMAQ; Shaocai Yu, U.S. EPA, for providing Fortran code for statistical calculations Jiming Hao and Ke-Bin He, Tsinghua University, China, for providing the observational data in Beijing, China Takigawa Masayuki, the Frontier Research Center for Global Change, Japan, for providing the codes for the extraction of Japan data