2. Method

2.2 Model simulations
The three-dimensional aerosol-transport-radiation model

Seasonal characteristics of particulate matter in Osaka
Makiko Nakata （Kinki University）

Abstract
Particulate matter (PM) is sampled widely worldwide because high PM concentrations can degrade air quality. Our groupmonitors PM in Osaka，the second largest metropolitan area in Japan. Because of industrial plants and highways locatednear our observation site，a clear atmosphere is rare in this area. The air is usually polluted with suspended particles emitted
from vehicles and industries. In this study，seasonal PM variation in Osaka using ground observation and model simulation isinvestigated. Results showed that PM concentrations were highest during spring and summer because of dust events in springand photochemical reactions in summer. As such，the inﬂuence of anthropogenic PM at this site is signiﬁcant during summer.

PM distribution in East Asia is complex due to both

SPRINTARS [9] was driven by the general circulation

the increasing emissions of anthropogenic particles thatmodel of the atmosphere ocean research institute (AORI)/

are associated with economic growth and the behavior of

NIES/ frontier research center for global change (FRCGC)

natural particles. PM has a number of impacts on the social

in Japan. The horizontal and vertical resolutions of theand natural environment. PM affects the Earth's radiation

triangular truncation were set at T42 (approximately 2.8

balance due to the scattering and absorbing of solar andby 2.8 degrees in latitude and longitude) and 20 layers，

thermal radiation as well as by altering the composition ofrespectively. A simplified mixed-layer ocean was used tothe atmosphere by triggering chemical reactions. Therefore，

simulate sea surface temperature changes driven by aerosols

detailed investigation of atmospheric particles is important.

using the prescribed surface heat ﬂux. The model considers

In this study，the characteristics of PM over East Asia werecarbonaceous，sulfate，dust，and sea salt aerosols，andinvestigated using a combination of ground measurements

aerosol transport processes，including emission，advection，and model simulations.

diffusion，wet deposition，dry deposition，and gravitational
settling. Emission inventory data on fossil fuel consumption，

2.1 Ground measurements
This study takes advantage of the simultaneous

fuel wood consumption，and forest ﬁres were used as inputs
for the carbonaceous and sulfate aerosols.

observations made at Osaka's Kinki University campus. In

1. Introduction

the aerosol robotics network (AERONET) site on the roof

2002，an AERONET station was set up at the university，of a building at Kinki University. Worldwide，National

which provides measurements of AOT and α. A PM sampler

Air pollution in megacities has become a serious problem.

Aeronautics and Space Administration (NASA)/AERONET

is also installed at the same AERONET site on the roof of a

In particular，fine particles called PM2.5，whose diameterdata are primarily available as ground-based sun-building 50 m above sea level.

is 2.5 μm or less，are problematic. Particulate matter (PM)photometric products that provide measurements of the

The data supplied by the Cimel instrument were analyzedof 15 μg/m3. The annual PM2.5 air average at our site waspollution characterized by high PM2.5 readings cause a spikeaerosol optical thickness (AOT) and the Ångström exponent

with a standard AERONET processing system to generate

about 20 μ g/m3，which exceeds Japan's quality standard.

in the mortality rate of patients suffering from heart and(α) [4，5]. Furthermore，at the same site，a standard lightvalues for AOT and α. The AOT resolution was better thanThis suggests that clear atmospheric conditions are rare inlung diseases. Because ﬁne particles are much smaller thandetection and ranging (LIDAR) instrument，which is part0.01 for all observation wavelengths，and cloud screening

the area and that suspended particles can usually be foundinhalable coarse particles，they penetrate deeper into theof the national institute for environmental studies (NIES)/

was performed on the data before aerosol retrieval [7]. AOT，

in the atmosphere.

lungs and more severely affect human health. Anthropogenic

LIDAR network [6]，has been set up.

the basic parameter for describing atmospheric aerosols，

sources of PM 2.5 include automobiles，factories，coal-indicates the degree of opacity; hence，the atmosphericburning power plants，and heaters in homes. In addition，concentration of aerosol particles [8].

Japan's environmental quality standards for PM2.5 area daily air average of 35 μg/m3 and an annual air average

3.1 Monthly mean
The SPM sampler measures PM concentrations every

dust particle size decreases as the particles are transported

The SPM-613D sampler collects suspended PM on ahour. Data with missing values and negative values are

via westerly winds over long distances; therefore，dust

teflon filter and measures the weight of the particles by

eliminated. The data is eliminated if the value of PM10

storms may contain high concentrations of ﬁne particles [1].

the absorbance of a beta ray. The PM sampler provides

concentration is smaller than that of PM 2.5. After data

Accordingly，PM2.5 concentration levels correspond withinformation separately on the concentrations of PM 2.5，

screening，the daily and monthly PM concentrations were

those of both anthropogenic and natural aerosols.

PM 10，and optical black carbon particles because it cancalculated. The monthly mean PM2.5 and PMC concentrations

Osaka is the central city in the second largest

separately determine the contributions of fine particles

at the Osaka site are shown in Fig. 2. The black and graymetropolitan area in Japan. The greater Osaka metropolitan(PM2.5) and coarse particles (PMC) to yield the differencelines indicate PM2.5 and PMC concentrations，respectively.

area covers 7,800 square kilometers within a radius of 50–

between PM 10 and PM 2.5 concentration levels. PM C is

The vertical lines show the maximum and minimum values

60 km from the center of Osaka. The population exceeds 17

generally a better indicator of dust events than PM 2.5

for these measurements. From this data，it is evident

million，making it one of the world's biggest metropolitan

because soil dust particles are typically large. A fieldthat PM2.5 concentrations were higher during spring andareas. Our observation site is located in eastern Osaka，asemission scanning electron microscope (SEM) equipped

summer. The concentrations decreased somewhat during theshown in Fig. 1. The area is known for its manufacturingwith an energy-dispersive X-ray analyzer (EDX) is an

monsoon in June. Although relatively high coarse particle

technologies by small- and medium-sized enterprises. Thiseffective instrument for observing surface microstructuresconcentrations were measured during spring，overall，ﬁne

area rarely experiences clear atmospheric conditions withand analyzing the chemical composition of materials suchparticle concentrations predominated at the Osaka site.

a limited number of small particles and often suffers highlevels of pollution from particles emitted from diesel vehicles
and industrial activities [2].
PM levels in Osaka are monitored with a PM sampler(SPM-613D，Kimoto Electric，Japan) [3]，installed at

123. Characteristics of particulate mattersFig. 1. Map of the observation site， located at 135.59°E， 34.65°N
in Osaka shown as a white circle. From Google Map

as metals，powders，and biological specimens. An SEM/

The AERONET-generated monthly mean AOT and α

EDX was used to analyze the PM from the PM sampler. The

values at the same site as shown in Fig. 3. AOT is the basic

SEM/EDX can detect elements from a sample，using theparameter for describing atmospheric aerosols. α is derived

X-rays emanating from the surface of the sample to provide

from the spectral AOT，as in Eq. (1)，where α represents

the mass concentration of each component.

the wavelength.

13

2. Method

2.2 Model simulations
The three-dimensional aerosol-transport-radiation model

Seasonal characteristics of particulate matter in Osaka
Makiko Nakata （Kinki University）

Abstract
Particulate matter (PM) is sampled widely worldwide because high PM concentrations can degrade air quality. Our groupmonitors PM in Osaka，the second largest metropolitan area in Japan. Because of industrial plants and highways locatednear our observation site，a clear atmosphere is rare in this area. The air is usually polluted with suspended particles emitted
from vehicles and industries. In this study，seasonal PM variation in Osaka using ground observation and model simulation isinvestigated. Results showed that PM concentrations were highest during spring and summer because of dust events in springand photochemical reactions in summer. As such，the inﬂuence of anthropogenic PM at this site is signiﬁcant during summer.

PM distribution in East Asia is complex due to both

SPRINTARS [9] was driven by the general circulation

the increasing emissions of anthropogenic particles thatmodel of the atmosphere ocean research institute (AORI)/

are associated with economic growth and the behavior of

NIES/ frontier research center for global change (FRCGC)

natural particles. PM has a number of impacts on the social

in Japan. The horizontal and vertical resolutions of theand natural environment. PM affects the Earth's radiation

triangular truncation were set at T42 (approximately 2.8

balance due to the scattering and absorbing of solar andby 2.8 degrees in latitude and longitude) and 20 layers，

thermal radiation as well as by altering the composition ofrespectively. A simplified mixed-layer ocean was used tothe atmosphere by triggering chemical reactions. Therefore，

simulate sea surface temperature changes driven by aerosols

detailed investigation of atmospheric particles is important.

using the prescribed surface heat ﬂux. The model considers

In this study，the characteristics of PM over East Asia werecarbonaceous，sulfate，dust，and sea salt aerosols，andinvestigated using a combination of ground measurements

aerosol transport processes，including emission，advection，and model simulations.

diffusion，wet deposition，dry deposition，and gravitational
settling. Emission inventory data on fossil fuel consumption，

2.1 Ground measurements
This study takes advantage of the simultaneous

fuel wood consumption，and forest ﬁres were used as inputs
for the carbonaceous and sulfate aerosols.

observations made at Osaka's Kinki University campus. In

1. Introduction

the aerosol robotics network (AERONET) site on the roof

2002，an AERONET station was set up at the university，of a building at Kinki University. Worldwide，National

which provides measurements of AOT and α. A PM sampler

Air pollution in megacities has become a serious problem.

Aeronautics and Space Administration (NASA)/AERONET

is also installed at the same AERONET site on the roof of a

In particular，fine particles called PM2.5，whose diameterdata are primarily available as ground-based sun-building 50 m above sea level.

is 2.5 μm or less，are problematic. Particulate matter (PM)photometric products that provide measurements of the

The data supplied by the Cimel instrument were analyzedof 15 μg/m3. The annual PM2.5 air average at our site waspollution characterized by high PM2.5 readings cause a spikeaerosol optical thickness (AOT) and the Ångström exponent

with a standard AERONET processing system to generate

about 20 μ g/m3，which exceeds Japan's quality standard.

in the mortality rate of patients suffering from heart and(α) [4，5]. Furthermore，at the same site，a standard lightvalues for AOT and α. The AOT resolution was better thanThis suggests that clear atmospheric conditions are rare inlung diseases. Because ﬁne particles are much smaller thandetection and ranging (LIDAR) instrument，which is part0.01 for all observation wavelengths，and cloud screening

the area and that suspended particles can usually be foundinhalable coarse particles，they penetrate deeper into theof the national institute for environmental studies (NIES)/

was performed on the data before aerosol retrieval [7]. AOT，

in the atmosphere.

lungs and more severely affect human health. Anthropogenic

LIDAR network [6]，has been set up.

the basic parameter for describing atmospheric aerosols，

sources of PM 2.5 include automobiles，factories，coal-indicates the degree of opacity; hence，the atmosphericburning power plants，and heaters in homes. In addition，concentration of aerosol particles [8].

Japan's environmental quality standards for PM2.5 area daily air average of 35 μg/m3 and an annual air average

3.1 Monthly mean
The SPM sampler measures PM concentrations every

dust particle size decreases as the particles are transported

The SPM-613D sampler collects suspended PM on ahour. Data with missing values and negative values are

via westerly winds over long distances; therefore，dust

teflon filter and measures the weight of the particles by

eliminated. The data is eliminated if the value of PM10

storms may contain high concentrations of ﬁne particles [1].

the absorbance of a beta ray. The PM sampler provides

concentration is smaller than that of PM 2.5. After data

Accordingly，PM2.5 concentration levels correspond withinformation separately on the concentrations of PM 2.5，

screening，the daily and monthly PM concentrations were

those of both anthropogenic and natural aerosols.

PM 10，and optical black carbon particles because it cancalculated. The monthly mean PM2.5 and PMC concentrations

Osaka is the central city in the second largest

separately determine the contributions of fine particles

at the Osaka site are shown in Fig. 2. The black and graymetropolitan area in Japan. The greater Osaka metropolitan(PM2.5) and coarse particles (PMC) to yield the differencelines indicate PM2.5 and PMC concentrations，respectively.

area covers 7,800 square kilometers within a radius of 50–

between PM 10 and PM 2.5 concentration levels. PM C is

The vertical lines show the maximum and minimum values

60 km from the center of Osaka. The population exceeds 17

generally a better indicator of dust events than PM 2.5

for these measurements. From this data，it is evident

million，making it one of the world's biggest metropolitan

because soil dust particles are typically large. A fieldthat PM2.5 concentrations were higher during spring andareas. Our observation site is located in eastern Osaka，asemission scanning electron microscope (SEM) equipped

summer. The concentrations decreased somewhat during theshown in Fig. 1. The area is known for its manufacturingwith an energy-dispersive X-ray analyzer (EDX) is an

monsoon in June. Although relatively high coarse particle

technologies by small- and medium-sized enterprises. Thiseffective instrument for observing surface microstructuresconcentrations were measured during spring，overall，ﬁne

area rarely experiences clear atmospheric conditions withand analyzing the chemical composition of materials suchparticle concentrations predominated at the Osaka site.

a limited number of small particles and often suffers highlevels of pollution from particles emitted from diesel vehicles
and industrial activities [2].
PM levels in Osaka are monitored with a PM sampler(SPM-613D，Kimoto Electric，Japan) [3]，installed at

123. Characteristics of particulate mattersFig. 1. Map of the observation site， located at 135.59°E， 34.65°N
in Osaka shown as a white circle. From Google Map

as metals，powders，and biological specimens. An SEM/

The AERONET-generated monthly mean AOT and α

EDX was used to analyze the PM from the PM sampler. The

values at the same site as shown in Fig. 3. AOT is the basic

SEM/EDX can detect elements from a sample，using theparameter for describing atmospheric aerosols. α is derived

X-rays emanating from the surface of the sample to provide

from the spectral AOT，as in Eq. (1)，where α represents

the mass concentration of each component.

the wavelength.

13

3.2 Seasonal change factors(1)
The α values are closely related to the aerosol size
distribution. Small α values indicate the presence of large
particles，and large values indicate small particles. In
general，α values from ~0 to 1.0 indicate large particles，such as sea salt aerosols and soil dusts，whereas values of
1.0 <α < ~2.5 indicate sulfate particles and those associatedwith biomass burning [10]. PM characterized by high AOT
and low α values is typical at the Osaka site during theperiod from March to May，as shown in Fig. 3.
These ground measurements indicate that PMconcentrations increase from spring to summer over Osakaand are characterized by a high concentration of coarse
particles in spring and a high concentration of ﬁne particles
in summer.

concentrations often increase during dust events.

4. PM Influence on radiation budget

Automobiles and factories use fossil fuels，which areimportant sources of PM2.5，during summer and other times

In addition to causing air pollution，PM may alsoof the year. During winter，coal-burning power plants andaffect the radiation budget. Therefore，we utilized model

household heat appliances use increased amounts of fuel.

simulations to investigate the inﬂuence of these effects.

China's Ministry of Environment Protection has reported
that up to 25% of the country was covered with a thick fog
during the winter of 2012/2013. Since seasonal winds can

4.1 Seasonal mean vertical and horizontal distributionof PM

carry pollution from China to Japan，during winter andFig.5 shows the two-month averaged sulfate aerosol massspring the northwest winds that dominate in Japan bringconcentration and winds at 850 hPa derived from the modelincreased levels of pollution into the country. In winter，

simulation. Sulfate aerosol is the major anthropogenic PM

high PM2.5 concentrations were observed occasionally，butemitted from the burning of fossil fuels. In winter，sulfate

the monthly mean PM2.5 concentrations in Japan were notaerosol is transported from China to western Japan byvery high. In addition，the atmosphere was relatively clear

northwest winds. Therefore，a high concentration of PM 2.5 isin autumn around the site.

often observed in western Japanese cities when air pollution

Fig. 4 (a) shows the frequency of the daily average PM2.5

occurs in eastern Chinese cities. However，the concentration

concentration being higher than 50 μ g/m3. This frequencyof sulfate aerosol transported to eastern Japan is low in

was highest in August，followed by May and July. The

winter. The region of large aerosol concentration extends

frequencies of photochemical smog and dust events in thefrom western to northern Japan in summer. The vertical

Osaka area are shown in Figs. 4 (b) and 4 (c)，respectively.

distribution of sulfate aerosol concentration from 110 °E to

Photochemical smog forecasts and advisories are issued

160 °E at 35 °N is shown in Fig. 6. The sulfate aerosol

when oxidant concentrations exceed 0.08 ppm and 0.12

elevation is low in winter and increases from spring to

ppm，respectively，and suitable weather conditions exist forsummer with the presence of warmer surfaces. In summer，

photochemical reactions. In summer，more sulfate aerosols

weather conditions are also suitable for photochemical

are produced by active photochemical reactions [11]. Hence，

reactions. The high concentration of PM2.5 in summer at

the frequent occurrence of high concentrations of aerosols

Osaka was caused by these factors.

from July to August is likely caused by photochemical
reactions. High PM2.5 concentrations were observed at oursite when photochemical smog was forecast or when smog
advisories were issued for the Osaka prefecture.
The observed dust events likely contributed to theFig. 2. Monthly mean PM2.5 and PMC concentrations [μg/m3 ] averaged
from 2008 to 2013 at the Osaka site (34.65°N，135.59°E). The vertical lines
show the maximum and minimum values for these measurements.

seasonal variations in coarse particle concentrations. The air
and ground conditions are suitable for dust events in spring，
due to the strong surface winds and dry land conditions.
On the other hand，in summer，winds weaken and thelands moisten. Dust events can also occur during autumn in
Asia，and dust has occasionally been observed during thisseason in Japan. Particle properties，such as amount，size，
shape，and composition，change in the Osaka area during
dust events. The elemental compositions were determinedby SEM/EDX analysis on a day with a dust event. On the
day without a dust event，the PM 10 ratio of silicon wasapproximately 30%. It is clear that silicon，which is possibly
from soil particles，was the dominant PM 10 constituent

Fig. 4. (a) Number of times daily average PM2.5 concentrations at the Osakasite were higher than 50 μg/m3 during each month of the year. (b) Numberof times that photochemical smog was forecast and advisories were issued
in Osaka prefecture. (c) Number of times that a dust event was observed in
Osaka prefecture. All data were averaged from 2008 to 2013.

on the day with a dust event [12]. Since the size of dust
particles decreases during long-range transport，the PM2.5
concentrations during dust event were high. Furthermore，Fig. 3. Monthly mean AERONET AOT and α values averaged from 2008 to2013 at the Osaka site (34.65°N，135.59°E).

fine anthropogenic particles can be transported to Japan
along with dust particles [12]. Consequently，PM 2.5
Fig. 5. Simulated two-month averaged sulfate aerosol mass concentration(μg/m3 ) and wind speed at 850 hPa.

1415

3.2 Seasonal change factors(1)
The α values are closely related to the aerosol size
distribution. Small α values indicate the presence of large
particles，and large values indicate small particles. In
general，α values from ~0 to 1.0 indicate large particles，such as sea salt aerosols and soil dusts，whereas values of
1.0 <α < ~2.5 indicate sulfate particles and those associatedwith biomass burning [10]. PM characterized by high AOT
and low α values is typical at the Osaka site during theperiod from March to May，as shown in Fig. 3.
These ground measurements indicate that PMconcentrations increase from spring to summer over Osakaand are characterized by a high concentration of coarse
particles in spring and a high concentration of ﬁne particles
in summer.

concentrations often increase during dust events.

4. PM Influence on radiation budget

Automobiles and factories use fossil fuels，which areimportant sources of PM2.5，during summer and other times

In addition to causing air pollution，PM may alsoof the year. During winter，coal-burning power plants andaffect the radiation budget. Therefore，we utilized model

household heat appliances use increased amounts of fuel.

simulations to investigate the inﬂuence of these effects.

China's Ministry of Environment Protection has reported
that up to 25% of the country was covered with a thick fog
during the winter of 2012/2013. Since seasonal winds can

4.1 Seasonal mean vertical and horizontal distributionof PM

carry pollution from China to Japan，during winter andFig.5 shows the two-month averaged sulfate aerosol massspring the northwest winds that dominate in Japan bringconcentration and winds at 850 hPa derived from the modelincreased levels of pollution into the country. In winter，

simulation. Sulfate aerosol is the major anthropogenic PM

high PM2.5 concentrations were observed occasionally，butemitted from the burning of fossil fuels. In winter，sulfate

the monthly mean PM2.5 concentrations in Japan were notaerosol is transported from China to western Japan byvery high. In addition，the atmosphere was relatively clear

northwest winds. Therefore，a high concentration of PM 2.5 isin autumn around the site.

often observed in western Japanese cities when air pollution

Fig. 4 (a) shows the frequency of the daily average PM2.5

occurs in eastern Chinese cities. However，the concentration

concentration being higher than 50 μ g/m3. This frequencyof sulfate aerosol transported to eastern Japan is low in

was highest in August，followed by May and July. The

winter. The region of large aerosol concentration extends

frequencies of photochemical smog and dust events in thefrom western to northern Japan in summer. The vertical

Osaka area are shown in Figs. 4 (b) and 4 (c)，respectively.

distribution of sulfate aerosol concentration from 110 °E to

Photochemical smog forecasts and advisories are issued

160 °E at 35 °N is shown in Fig. 6. The sulfate aerosol

when oxidant concentrations exceed 0.08 ppm and 0.12

elevation is low in winter and increases from spring to

ppm，respectively，and suitable weather conditions exist forsummer with the presence of warmer surfaces. In summer，

photochemical reactions. In summer，more sulfate aerosols

weather conditions are also suitable for photochemical

are produced by active photochemical reactions [11]. Hence，

reactions. The high concentration of PM2.5 in summer at

the frequent occurrence of high concentrations of aerosols

Osaka was caused by these factors.

from July to August is likely caused by photochemical
reactions. High PM2.5 concentrations were observed at oursite when photochemical smog was forecast or when smog
advisories were issued for the Osaka prefecture.
The observed dust events likely contributed to theFig. 2. Monthly mean PM2.5 and PMC concentrations [μg/m3 ] averaged
from 2008 to 2013 at the Osaka site (34.65°N，135.59°E). The vertical lines
show the maximum and minimum values for these measurements.

seasonal variations in coarse particle concentrations. The air
and ground conditions are suitable for dust events in spring，
due to the strong surface winds and dry land conditions.
On the other hand，in summer，winds weaken and thelands moisten. Dust events can also occur during autumn in
Asia，and dust has occasionally been observed during thisseason in Japan. Particle properties，such as amount，size，
shape，and composition，change in the Osaka area during
dust events. The elemental compositions were determinedby SEM/EDX analysis on a day with a dust event. On the
day without a dust event，the PM 10 ratio of silicon wasapproximately 30%. It is clear that silicon，which is possibly
from soil particles，was the dominant PM 10 constituent

Fig. 4. (a) Number of times daily average PM2.5 concentrations at the Osakasite were higher than 50 μg/m3 during each month of the year. (b) Numberof times that photochemical smog was forecast and advisories were issued
in Osaka prefecture. (c) Number of times that a dust event was observed in
Osaka prefecture. All data were averaged from 2008 to 2013.

on the day with a dust event [12]. Since the size of dust
particles decreases during long-range transport，the PM2.5
concentrations during dust event were high. Furthermore，Fig. 3. Monthly mean AERONET AOT and α values averaged from 2008 to2013 at the Osaka site (34.65°N，135.59°E).

fine anthropogenic particles can be transported to Japan
along with dust particles [12]. Consequently，PM 2.5
Fig. 5. Simulated two-month averaged sulfate aerosol mass concentration(μg/m3 ) and wind speed at 850 hPa.

1415

summer at Osaka.

【 References 】

2011.

[1] M. Mukai, T. Nakajima，and T. Takemura,“A study of long-[12] M. Nakata, I. Sano, S. Mukai, and B. N. Holben, “Spatial

term trends in mineral dust aerosol distributions in Asia

and Variations of Atmospheric Aerosol in Osaka,”using a general circulation model,”J. Geophys. Res. 109,

Atmosphere, 4(2), pp. 157-168, 2013.

D19, D19204 , 2004.
[2] M. Nakata, T. Yokomae, T. Fujito, I. Sano, and S. Mukai,“Characterization of aerosols based on the simultaneous
measurements,” in Proc. of IEEE/IGARSS, 978-1-45771005-6/11, 2011, pp. 4164-4167.
[3] S. Mukai, I. Sano, and B. N. Holben, “Aerosol properties
over Japan by sun/sky photometry,” Water, Air and Soil

◆著者紹介

Pollution, 5, pp. 133-143, 2005.
[4] B. N. Holben, T. F. Eck, I. Slutsker, D. Tanré, J. P. Buis, A.

Makiko Nakata

Setzer, E. Vermote, J. A. Reagan, Y. Kaufman, T. Nakajima,

近畿大学総合社会学部講師。

F. Lavenu, I. Jankowiak, and A. Smirnov, “AERONET - A

東京大学大学院理学研究科地球惑星科学専攻修了，博士（理学）。

federated instrument network and data archive for aerosol

元東京大学気候システム研究センター，独立行政法人宇宙航空研究開発

characterization,” Rem. Sens. Environ. 66, pp. 1-16, 1998.

機構（JAXA ）研究員。

[5] O. Dubovik, B. N. Holben, T. F. Eck, A. Smirnov, Y. J.
Fig. 7. Differences between the two experiments with respect to AOT， solar
radiation， and aerosol mass concentration， and the extinction coefficientnear the surface.

中田 真木子

これまで，大気環境解析，数値モデルシミュレーションの研究に従事。

Kaufman, M. D. King, D. Tanré, and I. Slutsker,“Variabilityof absorption and optical properties of key aerosol types
observed in worldwide locations,” J. Atmos. Sci. 59, pp. 590608, 2002.

5. Summary
Seasonal PM variations around Osaka，which is the second

Yamazaki, “Continuous observations of Asian dust and ither

4.2 Influence of PM on climate

largest metropolitan area in Japan，were investigated.

aerosols by polarization lidars in China and Japan during

Murayama, N. Kagawa, K. Aoki, A. Uchiyama, and A.

To investigate the impact of anthropogenic aerosols，

PM 2.5 concentrations were highest during spring andtwo sets of contrasting atmospheric conditions weresummer. The spring dust event increased levels of pollution[7] A. Smirnov, B. N. Holben, T. F. Eck, O. Dubovik, and I.

modeled. The first experiment used present-day (2000)

into the region with high concentrations of both coarse andSlutsker, “Cloud screening and quality control algorithms

emission data for anthropogenic aerosols (i.e.，sulfate andfine particles. Increase of sulfate aerosol concentrations

for the AERONET database,” Remote Sens. Environ. 73, pp.

carbonaceous aerosols)，and the second experiment usedproduced by photochemical reactions likely caused the high337-349, 2000.

ACE-Asia,” J. Geophys. Res. 109, pp. 1-14, 2004.

preindustrial (1850) emission data. The inputs of sulfate

concentrations of PM2.5 during summer. Model simulation[8] T. F. Eck, B. N. Holben, J. S. Reid, O. Dubovik, A. Smirnov,

and carbonaceous aerosols from the burning of fossil

results showed that the impact of anthropogenic PM at the

N. T. O'Neill, I. Slutsker, and S. Kinne, “Wavelength

fuels were neglected for the preindustrial-era model，andobservation site is signiﬁcant in summer.

dependence of the optical depth of biomass burning, urban,

the emission of carbonaceous aerosols from biofuels andagricultural activities were set to one-tenth of present-day

and desert dust aerosols,” J. Geophys. Res. 104, pp. 3133331349, 1999.

values. Both experiments were conducted using present-day[9] T. Takemura, T. Nozawa, S. Emori, T. Y. Nakajima, T.

greenhouse gas conditions. The differences between the two-

Nakajima, “Simulation of climate response to aerosol directmodeled experiments were considered to reﬂect the impact

and indirect effects with aerosol transport-radiation model,”of anthropogenic aerosols on climate.

16[6] A. Shimizu, N. Sugimoto, I. Matsui, K. Arao, U. Uno, T.

Fig. 6. Simulated two-month averaged vertical distribution of sulfate aerosol
mass concentration (μg/m3 ) at 35°N.

J. Geophys. Res. 110, 2005, doi:10.1029/2004JD005029.

The inﬂuence of anthropogenic aerosol，as estimated from[10] N. T. O'Neill, T. F. Eck, A. Smirnov, B. N. Holben, S.

the difference between the two experiments，is shown in Fig.

Thulasiraman, “Spectral discrimination of coarse and ﬁne

7. The increase in anthropogenic aerosols causes an increasemode optical depth, “J. Geophys. Res. 108, 4559, 2003,

in the extinction coefﬁcient near the surface and a decrease

doi:10.1029/2002JD0029753.

in solar radiation at Osaka. These changes are particularly[11] Y. Hara, I. Uno, A. Shimizu, N. Sugimoto, I. Matsui, K.

large in summer. The active photochemical reactions and the

Yumimoto, J. Kurokawa, T. Ohara, and Z. Liu, “Seasonalhigh aerosol values account for the remarkable AOT increasecharacteristics of spherical aerosol distribution in easternin summer. Therefore，an increase in anthropogenic aerosol

Asia: Integrated analysis using ground/space-based lidars

concentration leads to a large decrease in solar radiation in

and a chemical transport model,” SOLA, 7, pp. 121-124,

17

summer at Osaka.

【 References 】

2011.

[1] M. Mukai, T. Nakajima，and T. Takemura,“A study of long-[12] M. Nakata, I. Sano, S. Mukai, and B. N. Holben, “Spatial

term trends in mineral dust aerosol distributions in Asia

and Variations of Atmospheric Aerosol in Osaka,”using a general circulation model,”J. Geophys. Res. 109,

Atmosphere, 4(2), pp. 157-168, 2013.

D19, D19204 , 2004.
[2] M. Nakata, T. Yokomae, T. Fujito, I. Sano, and S. Mukai,“Characterization of aerosols based on the simultaneous
measurements,” in Proc. of IEEE/IGARSS, 978-1-45771005-6/11, 2011, pp. 4164-4167.
[3] S. Mukai, I. Sano, and B. N. Holben, “Aerosol properties
over Japan by sun/sky photometry,” Water, Air and Soil

◆著者紹介

Pollution, 5, pp. 133-143, 2005.
[4] B. N. Holben, T. F. Eck, I. Slutsker, D. Tanré, J. P. Buis, A.

Makiko Nakata

Setzer, E. Vermote, J. A. Reagan, Y. Kaufman, T. Nakajima,

近畿大学総合社会学部講師。

F. Lavenu, I. Jankowiak, and A. Smirnov, “AERONET - A

東京大学大学院理学研究科地球惑星科学専攻修了，博士（理学）。

federated instrument network and data archive for aerosol

元東京大学気候システム研究センター，独立行政法人宇宙航空研究開発

characterization,” Rem. Sens. Environ. 66, pp. 1-16, 1998.

機構（JAXA ）研究員。

[5] O. Dubovik, B. N. Holben, T. F. Eck, A. Smirnov, Y. J.
Fig. 7. Differences between the two experiments with respect to AOT， solar
radiation， and aerosol mass concentration， and the extinction coefficientnear the surface.

中田 真木子

これまで，大気環境解析，数値モデルシミュレーションの研究に従事。

Kaufman, M. D. King, D. Tanré, and I. Slutsker,“Variabilityof absorption and optical properties of key aerosol types
observed in worldwide locations,” J. Atmos. Sci. 59, pp. 590608, 2002.

5. Summary
Seasonal PM variations around Osaka，which is the second

Yamazaki, “Continuous observations of Asian dust and ither

4.2 Influence of PM on climate

largest metropolitan area in Japan，were investigated.

aerosols by polarization lidars in China and Japan during

Murayama, N. Kagawa, K. Aoki, A. Uchiyama, and A.

To investigate the impact of anthropogenic aerosols，

PM 2.5 concentrations were highest during spring andtwo sets of contrasting atmospheric conditions weresummer. The spring dust event increased levels of pollution[7] A. Smirnov, B. N. Holben, T. F. Eck, O. Dubovik, and I.

modeled. The first experiment used present-day (2000)

into the region with high concentrations of both coarse andSlutsker, “Cloud screening and quality control algorithms

emission data for anthropogenic aerosols (i.e.，sulfate andfine particles. Increase of sulfate aerosol concentrations

for the AERONET database,” Remote Sens. Environ. 73, pp.

carbonaceous aerosols)，and the second experiment usedproduced by photochemical reactions likely caused the high337-349, 2000.

ACE-Asia,” J. Geophys. Res. 109, pp. 1-14, 2004.

preindustrial (1850) emission data. The inputs of sulfate

concentrations of PM2.5 during summer. Model simulation[8] T. F. Eck, B. N. Holben, J. S. Reid, O. Dubovik, A. Smirnov,

and carbonaceous aerosols from the burning of fossil

results showed that the impact of anthropogenic PM at the

N. T. O'Neill, I. Slutsker, and S. Kinne, “Wavelength

fuels were neglected for the preindustrial-era model，andobservation site is signiﬁcant in summer.

dependence of the optical depth of biomass burning, urban,

the emission of carbonaceous aerosols from biofuels andagricultural activities were set to one-tenth of present-day

and desert dust aerosols,” J. Geophys. Res. 104, pp. 3133331349, 1999.

values. Both experiments were conducted using present-day[9] T. Takemura, T. Nozawa, S. Emori, T. Y. Nakajima, T.

greenhouse gas conditions. The differences between the two-

Nakajima, “Simulation of climate response to aerosol directmodeled experiments were considered to reﬂect the impact

and indirect effects with aerosol transport-radiation model,”of anthropogenic aerosols on climate.

16[6] A. Shimizu, N. Sugimoto, I. Matsui, K. Arao, U. Uno, T.

Fig. 6. Simulated two-month averaged vertical distribution of sulfate aerosol
mass concentration (μg/m3 ) at 35°N.

J. Geophys. Res. 110, 2005, doi:10.1029/2004JD005029.

The inﬂuence of anthropogenic aerosol，as estimated from[10] N. T. O'Neill, T. F. Eck, A. Smirnov, B. N. Holben, S.

the difference between the two experiments，is shown in Fig.

Thulasiraman, “Spectral discrimination of coarse and ﬁne

7. The increase in anthropogenic aerosols causes an increasemode optical depth, “J. Geophys. Res. 108, 4559, 2003,

in the extinction coefﬁcient near the surface and a decrease

doi:10.1029/2002JD0029753.

in solar radiation at Osaka. These changes are particularly[11] Y. Hara, I. Uno, A. Shimizu, N. Sugimoto, I. Matsui, K.

large in summer. The active photochemical reactions and the

Yumimoto, J. Kurokawa, T. Ohara, and Z. Liu, “Seasonalhigh aerosol values account for the remarkable AOT increasecharacteristics of spherical aerosol distribution in easternin summer. Therefore，an increase in anthropogenic aerosol

Asia: Integrated analysis using ground/space-based lidars

concentration leads to a large decrease in solar radiation in

and a chemical transport model,” SOLA, 7, pp. 121-124,

17