Hong Liao

Institute of Atmospheric PhysicsChinese Academy of Sciences

Simulation of Air Pollutants (AP) over China using the GEOS-CHEM

What do we know about AP over China?

Column burden of tropospheric NO2 over 1996-2006

( 1015 molecules cm-2)

GOME NO2 Measurements Four heavily polluted areas:

Northern China，Yangtze Delta,

Sichuan Basin,

and Pearl River Delta

High concentrations:

PM2.5 concentrations are about 10-15 times the US Values!

What don’t we know about AP over China?

Seasonal variation

Previous modeling and measurements mostly focused on a short period of time and a specific location

Chemical composition of aerosols

Few sites with long-term speciated measurements

Location Period Value Reference

Qingdao

24 Feb–15 Mar, 2002 26.6 ppbv

Takami et al. (2006)

16 Feb–28 Feb, 2001 23.5 ppbv

15 Jan–28 Jan, 2000 35.9 ppbv

Fenghuanshan16 Feb–02 Mar, 2001 30.2 ppbv

13 Jan–25 Jan, 2000 32.2 ppbv

Waliguan, Qinghai-Tibetan Plateau (36.28N, 100.90E)

20 April to 23 May and 15 July

to 16 August. 2003

Spring 589 ppbv

Wang et al. (2006)Summer 5411 ppbv

Lin’ an 18 February to 30 April 2001 34 ppbv Wang et al. (2004)

cape D'Aguilar, Hong Kong (2213’N, 11415’E)

October and November 1997 5011 ppbv Wang et al. (2001)

Qindao (120.5E, 36.1N) June 1995 35 ppbv Li et al. (1999)

Chnshu (119.44E, 30.28N) June 2000 45 ppbv Yan et al. (2003)

Lin’An (120.38E, 31.33N) June 2000 40 ppbv Yan et al. (2003)

Qindao (120.5E, 36.1N)) Dec. 1994 23 ppbv Li et al. (1999)

Chnshu (119.44E, 30.28N) Dec. 1999 22 ppbv Yan et al. (2003)

Lin’An (120.38E, 31.33N) Dec. 1999 32 ppbv Yan et al. (2003)

Waliguan mountain (3617’N, 10054’E)

September 1999 to June 2001

44.9 ppb

Carmichael et al. (2003)

Linan (3018’N, 11944’E) 38.3 ppb

Shang dian Zhi (4039’N, 11707’E) 38.0 ppb

Cape D’Aequier (2212’N, 11415’E) 34.9 ppb

Ground Measurements of Ozone in China

MISR Aerosol Optical Depth(June-August )

Aerosols over Beijing

Species Winter (μg/m3)

Spring (μg/m3)

Summer (μg/m3)

Fall (μg/m3)

Average (μg/m3)

PM10 153.8 188.5 118.5 156.6 154.5

PM2.5 122.09 76.41 88.99 79.8 101.75

NO3- 10.72 4.66 5.36 8.18 7.36

SO42- 9.88 6.71 13.43 9.61 10.22

NH4+ 7.13 4.13 5.90 5.94 5.62

Ground measurements at Beijing for 2001

AERONET AODs at Beijing(averaged over 2001-2005)

Location Time Period Measurements( g m-3)

Reference

Beijing Jul –Aug, 2002 12.44.4 He et al. (2004)

Beijing Aug 2003 19.2 Chan et al. (2005)

Beijing Jul 1999 – Sep 2000 Summer: 13.4

He et al. (2001)Autumn: 28.8

Winter: 31.5

Spring: 18.2

Xi’an Fall 2003 34.118.0 Cao et al. (2005)

Shanghai Mar 1999 - Mar 2000 Spring: 16.1

Zhang et al., (2004)Summer: 9.62

Autumn: 15.22

Winter: 16.40

Pearl River Delta Nov. 2000 19.2 Zhang et al. (2004)

Yangtze Delta Nov. 1999 33.1 Zhang et al. [2004]

Macao Dec. 2001Dec. 2002

12.2 Wu et al. (2004)

Hong Kong Nov. 2000 - Feb. 2001 8.3 Ho et al. (2003)

Hong Kong Nov. 2000-Feb. 2001 Jun. – Aug., 2001 8.2 Ho et al. (2006)

Lin’an Feb. – Apr., 2001 21.5 Wang et al. (2004)

Ground Measurements of OC

Organic30%

Trace2%

Crustal20%Ammonium

6%

Sulfate17%

Chloride2%

EC3%

Nitrate10%

Unknow10%

Annual Average Conc. of PM2.5 at Beijing in year 2000: 95.5 (μg m-3 )

OC Accounts for a Large Fraction of PM2.5

Zhang et al., 2002

Ground Measurements of Sulfate

GEOS-Chem Simulation over China

(GEOS-3 met fields, default emissions)

GEOS-Chem Prediction of Sulfate

The GEOS-Chem captures qualitatively the maximum concentrations in winter, but predicted concentrations have a low bias throughout the year.

Predicted distribution of maximum concentrations does not match well with that observed by satellites.

January

July

(μg m-3)

GEOS-Chem Prediction of Nitrate and Ammonium

(January) (July)

(μg m-3)

3NO

3NO

(January) (July)4NH

4NH

GEOS-Chem Prediction of Carbonaceous Aerosols

Carbonaceous aerosol concentrations are too low as comparedwith ground measurements!

BC (January) BC (July)

OC (January) OC (July)

(μg m-3)

GEOS-Chem Prediction of PM2.5 Concentrations

Concentrations are not as high as ground measurements, especially in summer.

January July

(μg m-3)

Plans to Improve the GEOS-Chem Simulation over China

Update emission inventories Simulation with David Streets’ year 2000 emission inventories produces better distribution of air pollutants but lower concentrations than that with default emissions.

Constrain sulfur emissions by ground measurements of SO2

China has long-term measurements of SO2 at many locations.

Constrain emissions of NOx, VOCs, and CO by satellite measurements

Ways to constrain BC and OC emissions? Suggestions are welcome!

Compare GEOS-Chem Simulated AODs with MeasurementsFrom Chinese Sun Hazemeter Network

Xin et al., JGR, 2007

Ongoing Research

Improve and evaluate simulation of AP over China

Better understanding of intercontinental transport More accurate boundary conditions for regional air quality modeling

Examine how Asian monsoon influences AP

Near Future Application of the GEOS-Chem

To understand the general characteristics of AP over whole China domain (GEOS-Chem)

Geographical distribution and seasonal variation; Chemical composition.

Simulation of severe pollution episodes (GEOS-Chem/MM5/CMAQ)

Forecast of severe pollution events (GEOS-Chem/MM5/CMAQ)

Assessment of future changes of Asian pollutants Short term (5-10 years) (GEOS-Chem/MM5/CMAQ) Long term (50 years) (GCM/MM5/CMAQ)

The End

Thank you!