Time series of satellite-based fine particulate matter (PM

2.5

) concentrations over China: 2004-2012

Guannan Geng, Qiang Zhang, Aaron van Donkelaar, Randall V. Martin, and Kebin He 2013-12-11, San Francisco

Sources and negative effects of fine particles (PM 2.5

) Health Haze Acid rain Brown Cloud

Climate

fine particulate matters in the (ambient) air with 2.5 micrometers or less in size Increased morbidity and mortality from both acute and chronic exposure to ambient fine particulate matter (PM 2.5

)

Regional haze is a major concern in China Primary pollutants in 74 cities (2013.1-10) PM 2.5

concentration (2013.1-10) Beijing haze Heavy PM 2.5

pollution occurs in China, especially in the North China Plain

How has PM 2.5

China?

evolved over the past decade over • Long-term variation of PM 2.5

for epidemiological studies.

concentrations is important • China has developed control strategies for the precursors of PM 2.5

, e.g. SO 2 and NO x .

• But ground measurements are limited in China – Only several research groups have monitored the ground level PM 2.5

concentration before the year 2013.

– National network of PM 2.5

monitoring is built up since 2013.

Satellite Remote sensing approach can be used to enhance our ability to estimate PM 2.5

concentration • Many works have used aerosol optical depth (AOD) to retrieve PM 2.5

concentration Multiple linear regression 𝑷𝑴 𝟐.𝟓 = 𝒇(𝑨𝑶𝑫) Chemical transport model • In this study, ground-level PM 2.5

period 2004-2012 over China concentrations for the are estimated using CTM to provide the conversion factor between PM 2.5

and AOD.

Satellite-derived surface PM 2.5

MEIC emissions MISR GEOS-Chem

(

GC

)

CALIPSO AOD PM 2.5

AOD Vertical Profile

𝑨𝑶𝑫 𝒔𝒂𝒕𝒆𝒍𝒍𝒊𝒕𝒆 × 𝑷𝑴 𝟐.𝟓_𝒎𝒐𝒅𝒆𝒍𝒆𝒅 𝑨𝑶𝑫 𝒎𝒐𝒅𝒆𝒍𝒆𝒅 𝑷𝑴 𝟐.𝟓_𝒔𝒂𝒕𝒆𝒍𝒍𝒊𝒕𝒆 van Donkelaar et al, EHP, 2010 van Donkelaar et al, JGR, 2013

Emission trends of the precursors in China • The MEIC inventory, 2004-2012

Evaluation of model simulations SNA simulation in the year of 2006

Slope = 0.28, R = 0.32

Slope = 0.26, R = 0.33

Slope = 0.19, R = 0.17

Slope = 0.85, R = 0.39

Slope = 0.44, R = 0.81

Slope = 0.52, R = 0.78

Slope = 0.68, R = 0.71

Slope = 0.86, R = 0.88

Slope = 0.58, R = 0.66

Slope = 0.79, R = 0.82

Slope = 0.64, R = 0.49

Slope = 0.93, R = 0.74

Modeled AOD trend compared with MISR

Satellite-based PM 2.5

retrieved from MISR AOD

Trends of the conversion factor and MISR AOD Modeled PM 2.5

Modeled AOD Modeled PM 2.5

/AOD MISR AOD

The population weighted national annual mean PM 2.5

trends over China during 2004-2012 10 4

PM 2.5

trends of some cities in China

The effect of the correlation slope between modeled and satellite AOD on PM 2.5

trend 𝑷𝑴 𝟐.𝟓_𝒔𝒂𝒕𝒆𝒍𝒍𝒊𝒕𝒆 = 𝑨𝑶𝑫 𝒔𝒂𝒕𝒆𝒍𝒍𝒊𝒕𝒆 × 𝑷𝑴 𝟐.𝟓_𝒎𝒐𝒅𝒆𝒍𝒆𝒅 𝑨𝑶𝑫 𝒎𝒐𝒅𝒆𝒍𝒆𝒅

Conclusions • National scale surface PM 2.5

concentration derived from MISR increased from 2004 to 2006 and started to decrease around 2006 2007 , and had a second small peak in 2011 . The trend between 2004 and 2012 was +0.5

ug·m -3 ·yr -1 .

• In the Northern China, there are mostly increasing trends, even above 4 ug·m -3 ·yr -1 in some regions. While in the Southern China, PM 2.5

decreased in 2012 compared to 2004.

• PM 2.5

concentrations in some megacities have started to decrease slightly.