Optical remote sensing of atmospheric pollutants

大気汚染物質の光学的リモートセンシング

Center for Environmental Remote Sensing (CEReS), Chiba University

Hiroaki Kuze, Professor, Dr.Sc.hkuze@faculty.chiba-u.jp

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2016年 RS環境情報学 I

Air pollution大気汚染

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Urban smog: PM2.5

Los Angels Alberta, Canada

Beijing

http://ipod.item-get.com/2013/01/pm25.php 3

PM2.5, PM10 and SPM➣ In USA, a new environmental standard of PM2.5 was added in 1997 to the existing standard of PM10.➣ In Japan, the standard for PM10 was established in 1972. The suspended particulate matter (SPM) was defined as particles with diameters less than 10 m.

http://www.nies.go.jp/kanko/news/20/20-5/20-5-05.html

Col

lect

ion

Effic

ienc

y

Particle Diameter (m) 4

PM2.5 production in the atmosphere

UV photons produce ozone from VOC & NOx

人為起源

自然起源

http://www.env.go.jp/air/osen/pm/info.html

VOC SOxNOx

PM2.5

O3

NMHC

SPM

NMHC (nonmethane hydrocarbons 非メタン炭化水素) VOC (volatile organic compounds 揮発性有機化合物)

VOC

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Asian dust event observed on April 8, 2006

Aqua/MODIS visible band (RGB)

http://fujin.geo.kyushu-u.ac.jp/~hayasaki/

SPM distribution on the same day, (11:00, 14:00, and 23:00) observed at 1500 General (non-roadside) sampling stations.

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http://soramame.taiki.go.jp/

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Andersen Sampler (Multi-stage cascade impactor)

http://www.h2.dion.ne.jp/~yokke/study/atmosphere/air_pm/air_pm.html

Aerosol particles accumulate on a filter paper.

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http://www.t-dylec.net/products/pdf/thermo_5030.pdf

Sampling instrument for SPM & PM2.5【Hybrid monitor SHARP5030 】

○ 分粒装置で分粒された気流は、除湿部を通過して検出部へ入る。 Sampled air is introduced into the detector part through the dehumidify section.

○ 光散乱測定部（ネフェロメータ）では、エア

ロゾルの通過により発生する散乱光の強度から、濃度を測定（光散乱法）。光源の波長は880 nmである。 A nephelometer is used for measuring light scattering signals.

○ ネフェロメータを通過後、エアロゾルはグラ

スファイバーフィルタの上に捕集される。捕集前後のβ 線強度を検出し、その減衰量からエアロゾルの質量を計測する（β 線吸収法）。β 線は、14Ｃから放射される。A β ray counter is employed for the aerosol mass measurement.

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日本のエネルギー供給量

http://www.j-ec.or.jp/ecinfo/HoukiKankyo/kankyomondai3_1_1-1-2.html

○ 日本の実質経済成長率は、昭和30年代の約9％から昭和40年代前半には約11％に上昇した。Economic growth rate was 11% in mid 1960s.

○ 昭和36年には石油需要が石炭需要を上回り、昭和30年から昭和36年の間にエネルギーの総供給量も約２倍に増加した。 Oil consumption drastically increased during 1955-1960.

○ 昭和40年頃の大気汚染が最も著しかった時期には、場所によっては、硫黄酸化物やばいじん等によって視程が30～50 m にまで落ち込むとともに、硫黄酸化物による刺激臭が立ちこめているところもあった（四日市、川崎、千葉、北九州 ...）。Because of air pollutants, visibility decreased to 30 m in industrial areas.○ こうした深刻な環境汚染は公害と呼ばれた。昭和30年代から40年代にかけ、いわ

ゆる四大公害病（水俣病、新潟水俣病、イタイイタイ病、四日市ぜんそく）の発生など大きな社会問題になった。 Serious illness like mercury pollution, Asthma, etc.

経済成長期の公害 Pollution in Japan

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Mizushima Industrial Complex

Sapporo in 1970s PM2.5 in Beijing

大気汚染の記録写真

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Long-term trend of NO2 and SPM concentration

NO2 concentration

SPM concentration

Roadside

Roadside

General

General

ppm

mg/

m3

Ground sampling measurement at around 2000 stations (roadside: 500)

Environmental standard

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SO2 emission

In Japan:1970-2010 0.035 ppm→ 0.003 ppm(sampling station measurement)

http://www.nies.go.jp/kanko/tokubetu/setsumei/sr-065-2006b.html

kilo-ton SO2in 0.5o×0.5o

mesh(2000)

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1970-2010

Global distribution of PM2.5

(g/m3)

Donkelaar et al., http://ehp.niehs.nih.gov/0901623/

➣The global ground-level PM2.5 concentrations are mapped using total column aerosol optical depth (AOD) from the MODIS and MISR satellite instruments and coincident aerosol vertical profiles from the GEOS-Chem global chemical transport model. Global estimates of long-term average (1 January 2001 to 31 December 2006) PM2.5 concentrations at approximately 10 km × 10 km resolution indicate a global population-weighted geometric mean PM2.5 concentration of 20 µg/m3.

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Q1 大気汚染の原因となる物質にはどのようなものがあるか。Describe important substances that cause air pollution.

Q2 エアロゾルとは何か。日常生活にどのような影響を与えているか。What are aerosol particles? What influences do they have in our daily life?

Mie scattering of aerosol

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http://en.wikipedia.org/wiki/File:Atmospheric_electromagnetic_opacity.svg

Atmospheric Opacity 大気の不透明度

Wavelength

Opa

city

=3 m =100 MHz=30 cm =1 GHz

大気の窓可視 近赤外 電波

Molecular absorption is absent in visible range→ Atm. visibility is controlled by aerosol particles

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大気の鉛直透過における散乱と吸収の光学的厚さVertical optical thickness due to scattring and absorption

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光学的厚さ Optical thickness Vertical radiation transfer when J = 0

IdzdI

constant α

eI

eI

TIIz

0

0

0

Lambert-Beer’s law

0I

eI0 =α z =nz : optical thickness

（=1 I = 0.37I0 ）

➣ Clouds appear white, since wavelength dependence of Mie scattering is moderate.➣ White haze is due to the presence of aerosol particles.

ミー散乱 Mie scattering

Gustav Mie 1869-195719

冬季の接地逆転層Inversion layer in winter morning

12:19 on 19 January 2010 at CEReS, Chiba University

Temperature

Alti

tude

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Aerosol particles and gaseous pollutants

エアロゾル粒子 Aerosol particles➣ Aerosol – liquid or solid particles floating in the atmosphere. The diameter varies from 10 nm to 10 m.➣ Cloud droplet – also, liquid or solid (ice) particles, but with larger diameters of 10-100 m.➣ Mie scattering occurs since the size of aerosol and cloud particles are similar to or larger than the optical wavelength. Aerosol Cloud

(satellite image)soot

hygroscopic saltsea salt

Indoor aerosol1m

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0.0

0.5

1.0 Soil Sea Salt Nitrate Sulfate Organics EC

Volu

me r

atio

0.0

0.5

1.0

Volu

me r

atio

1999 2000 2001 2002 2003 20040.0

0.5

1.0Coarse

Volu

me r

atio

Fine

Long-term aerosol analysis at Chiba UniversityFine particles

Coarse particles

S. Fukagawa et al., Atmos.Environ., 40, 2160-2168 (2006) 22

Clean room

http://ja.wikipedia.org/wiki/

➣ Particles larger than 0.5 m, including floating bacteria and fungi, should be removed for medical and food industry.➣ Particles larger than 0.5 – 1 m must be removed in the case of semi-conductor manufacturing.➣ Ambient atmosphere corresponds to 1E+06 under clear sky. The number density drastically decreases under rainy conditions (600,000 – 200,000).

unit: particles/m3

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入射太陽エネルギー(100)

大気と雲による吸収(25)

大気と雲による反射(25)

反射太陽エネルギー(30)

(25)

(29) (12) (4)

大気と雲からの再放射(25)

外向き赤外光エネルギー(70)

地表面による吸収(45) 地表面による

反射(5)

水蒸気の凝結

地表面からの再放射

(104)温暖化気体の効果

(88)

再吸収

潜熱

(24)

対流

（5）

海流による熱の輸送

Principles of Environmental Science

Aerosols and clouds - large impact on the Earth's radiation budget

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http://www.mri-jma.go.jp/Project/1-21/1-21-1/aerosol-en.htm

How aerosols control the atmosphere

放射の直接効果 放射の間接効果

放射の散乱と吸収 雲の凝結核としての作用

湿性沈着

ジメチルサルファイド

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Global map at 18 km resolution showing monthly average AOT at 865 nm over water surfaces for June, 1997, derived from radiancemeasurements by POLDER aboardADEOS satellite.

POLDER (POLarization and Directionality of the Earth‘s Reflectance) ADEOS (ADvanced Earth Observing Satellite)[August 1996]

Global distribution of aerosol optical thickness (AOT)

J. Heintzenberg et al.,, Atmospheric chemistry in a changing world 26

Q1 大気汚染の原因となる物質にはどのようなものがあるか。Describe important substances that cause air pollution.

Q2 エアロゾルとは何か。日常生活にどのような影響を与えているか。What are aerosol particles? What influences do they have in our daily life?

Q3 エアロゾルが地球の放射収支に与える影響を直接効果、間接効果を含めて説明しなさい。Discuss how aerosols impact the Earth's radiation budget, including both direct and indirect effects.

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http://www.horiba.com/scientific/products/particle-characterization/

Mie scattering includes all the optical processes of reflection, refraction, and diffraction, etc.

Forward scattering becomes dominant for larger particles.

http://homework.uoregon.edu/pub/class/atm/scatter.html 28

2

22

21

20

20

2)()(

)(k

FFRI

dd

RII scat

Scattered radiance

Differential cross-section

1

1 coscos112

lllll ba

lllF

Scattering amplitude

cossin

1cos 1ll P

1

2 coscos112

lllll ab

lllF

,

coscos 1ll P

dd

Associated Legendre function

ミー散乱理論 Mie theory

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kakannkakan

kakannkakanallll

lllll

~~ ~ ~~ ~

：complex refractive indexn~

：radius of the spherea

/2k kakankakann

kakankakannbllll

lllll

~ ~~ ~ ~~

sin11 1

lll

l dd

cos11 1

lll

l dd

lln i

Complex refractive index and radius of dielectric sphere

wavenumber

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l-th partial wave

：complex refractive indexn~

a : radius of the sphere

/2k wavenumber

Absorptive particles

Complex refractive index of aerosol species

Complex refractive index, wavelength, and particle radius are important parameters for carrying out Mie-scattering calculations.

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dd

RII scat 2

0)(

1

222

2

0 0

)12(2

sin

l ll

scatscat

balk

ddd

d

Differential cross-section for the scattering angle of

Total cross-section for Mie-scattering of a single particle

Extinction efficiency2a

Q scatscat

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Size parameter dependence of the total cross-section

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Size distribution for typical aerosol models

3

1

2

0

21

2n n

n

n

n rrNrd

dN log

)/log(exp

)(log)(logLognormal size distribution

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Calculation of wavelength dependence of extinction coefficient for typical aerosol models 典型的なエアロゾルモデルに対する消散係数の波長依存性の計算

22 )(),(log

)(log)(max

min rrQrd

rddNrQr ext

extext

r

rM

3

1

2

0

log)/log(

21exp

)(log2)(log n n

n

n

n rrNrd

dN

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Q1 大気汚染の原因となる物質にはどのようなものがあるか。Describe important substances that cause air pollution.

Q2 エアロゾルとは何か。日常生活にどのような影響を与えているか。What are aerosol particles? What influences do they have in our daily life?

Q3 エアロゾルが地球の放射収支に与える影響を直接効果、間接効果を含めて説明しなさい。Discuss how aerosols impact the Earth's radiation budget, including both direct and indirect effects.

Q4 本日の講義から得られた新しい考え方や知識 （なるべくたくさん） What's new -New ideas and knowledge thorough this lecture?

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