section 11 case studies of episodes

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Section 11Case Studies of Episodes

What is a Case Study?

How to Conduct Case Studies

Examples

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Section 11 – Case Study of Episodes

What is a Case Study?

Analysis of the causes of an air quality episode

Case studies provide insight into important processes

Components of a case study• Air quality conditions• Weather situation• Summary of episode

– Important air quality processes– Important meteorological processes

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● Select a few air quality episodes to study– Include ramp-up and cleanout days

● Review locations, magnitude, and duration of poor air quality

● Review surface and upper-air weather patterns● Create backward trajectories to estimate transport● Estimate upwind air quality to quantify local versus

background contributions ● Review the temperature soundings to estimate

vertical mixing● Summarize the important processes that produced

the episode

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ExamplesEach example includes

• Location and background • Air quality conditions• Weather situation (surface, upper-air, stability, winds, etc.)• Summary of episode (air quality and meteorology)

Case study examples• PM10 episode

• Ozone episode

• PM2.5 episode

• CO episode• Long-range transport episode• Multi-pollutant episode• Smoke episode

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Case Study of PM10 Episode in Cairo, Egypt

● Location and background● Air quality conditions● Weather situation● Summary of episode (air quality and

meteorology)

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Location – Cairo, Egypt

Cairo

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Air Quality Conditions

Time series plot of PM10 concentrations in Cairo in October 1999. The

October 20-25, 1999, episode is outlined (Dye et al., 2000).

0

100

200

300

400

500

600

700

Conc

entra

tion

(ug/

m3)

PM 10 CAIRO

PM 10 M ed ianP M 1 0 C a ir o is th e a v e r a g e o f Q u a la ly , A b b a s s ia , a n d G iz aP M 1 0 m e d ia n is th e m e d ia n c o n c e n t r a t io n a t a l l C a ir o m o n ito r in g s i te s

PM

10 C

once

ntra

tion

(ug/

m3 )

D a te

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Surface and upper-air weather patterns

500-mb heights (dm) (solid) and 850-mb temperatures (oC) (dashed) (left), and sea level pressure (mb) and surface wind flags (right) on October 20, 1999, at 1400 LT

H

Weather Situation (1 of 6)

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500-mb heights (dm) (solid) and 850-mb temperatures (oC) (dashed) (left), and sea level pressure (mb) and surface wind flags (right) on October 23, 1999, (high PM day) at 1400 LT


Weak trough just passed

L

Light northerly

winds


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500-mb heights (dm) (solid) and 850-mb temperatures (oC) (dashed) (left), and sea level pressure (mb) and surface wind flags (right) on October 25, 1999, (cleanout day) at 1400 LT


Strong trough just passed

Moderatenortherly

winds


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12-hr backward trajectories ending in Cairo at 1400 LT each day October 20 to 25, 1999.

Backward trajectories to estimate transport


29.5

30

30.5

31

31.5

32

29.5 30 30.5 31 31.5 32 32.5Longitude (degrees)

Lat

itu

de

(deg

rees

)

20-Oct

21-Oct

22-Oct

23-Oct

24-Oct

25-Oct

21

23

24

2522

20

Short transport on high PM day

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0200 LT temperature soundings taken at Helwan from October 20 to 25, 1999.

Upper-air nighttime soundings to estimate vertical mixing

Warming

0

500

1000

1500

2000

2500

3000

10 15 20 25 30

20-Oct

21-Oct

22-Oct

23-Oct

24-Oct

25-Oct

Temperature (ºC)

Hei

gh

t (m

)

21 2223 24

25

20

StrongInversion


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1400 LT temperature soundings taken at Helwan from October 20 to 25, 1999.

0

500

1000

1500

2000

2500

3000

10 15 20 25 30

20-Oct

21-Oct

22-Oct

23-Oct

24-Oct

25-Oct

Temperature (ºC)

Hei

ght

(m)

21 22

2325

24

20

Warming

Upper-air daytime soundings to estimate vertical mixing


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Episode characteristics• Weak upper-level troughs passed over and north of Egypt

• The troughs lowered surface pressures to the north, thereby weakening the northerly winds, but winds still remained light-to-moderate from the north

• Aloft temperatures warmed, the capping inversion lowered, and vertical mixing was reduced

• Despite the moderately strong northerly winds, the reduced vertical mixing allowed for high PM10 concentrations

• The episode ended when a strong trough followed by a ridge passed over Egypt, increasing the northerly winds and weakening the inversion

Summary of Episode

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Examples● GTT – Please provide examples of other case studies● For each example include

– Location and background – Air quality conditions– Weather situation (surface, upper-air, stability, winds, etc.)– Summary of episode (air quality and meteorology)

● Case study examples– Ozone episode– PM2.5 episode– PM10 episode (done)– CO episode– Long-range transport episode– Multi-pollutant episode– Smoke episode

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Case Study of Ozone Episode

● Location and background● Air quality conditions● Weather situation● Summary of episode (air quality and

meteorology)

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Youngstown, Ohio, USA Summer 2002

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500-mb Heights Surface Pressure (msl) 24-hr Backward Trajectory

Jun 07th 12:00 pm EST

H


H

H


HH

L


H

HH


HH

L


L L

Case Study of Ozone Episode9-11 June 2002 Episode

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160

7-Jun8-Jun

9-Jun10-Jun

11-Jun

12-Jun

13-Jun

Ma

xim

um

AQ

I*

* **

**

YoungstownRegional 8-hr O3 Maximum

*


L

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Jul 06th 12:00 pm EST

H


500-mb Heights Surface Pressure (msl) 24-hr Backward Trajectory

8 July 2002 Episode

0

20

40

60

80

100

120

140

160

Ma

xim

um

AQ

I

* *

*


H

**

YoungstownRegional 8-hr O3 Maximum

HH


L


H


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Episode characteristics• Ridge of high pressure created high pressure

system• Recirculation was important for the 9-11 June

and July 8, 2002• Episodes occurred on weekdays, which

typically have higher emission patterns• Trajectories are useful for diagnosing air

movement• Transport of ozone from upwind regions

contributed to the ozone on 11 June 2002

Summary of Ozone Episodes

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Case Study of Ozone Episode in Sydney, Australia

● Ozone episode

SYDNEYSYDNEY

AUSTRALIAAUSTRALIA

200 250 300 350 400 450 500

EASTIN G (km )

6150

6200

6250

6300

6350

6400

NO

RT

HIN

G (

km)

SYD N EY

M U SW ELLBR O O K

N EW C ASTLE

PIC TO N

W O LLO N G O N G

PEN R ITH

LITH G O W

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150.5 150.6 150.7 150.8 150.9 151.0 151.1 151.2 151.3 151.4

LO N G ITU D E (degrees)

-34.1

-34.0

-33.9

-33.8

-33.7

-33.6

LAT

ITU

DE

(de

gre

es)

BLAC

BRIN

CAMD CAMP

EARL LIDC

LIND

LIVE RAND

RICH

ROZE

ST.M

VYNE

WSTM

WOOL TASM AN

SEA

Lindfield Ozone

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140

0 12 0 12 0 12

Time (h)

Co

nc

(pp

b)

O3 (obs)

O3 (ctm)

Woolooware Ozone

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120

140

0 12 0 12 0 12

Time (h)C

on

c (p

pb

)

O3 (obs)

O3 (ctm)

Camden Ozone

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140

0 12 0 12 0 12

Time (h)

Co

nc

(pp

b)

O3 (obs)

O3 (ctm)

Bargo Ozone

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140

0 12 0 12 0 12

Time (h)

Co

nc

(pp

b)

O3 (obs)

O3 (ctm)

Bringely Ozone

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140

0 12 0 12 0 12

Time (h)

Co

nc

(pp

b)

O3 (obs)

O3 (ctm)

Liverpool Ozone

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140

0 12 0 12 0 12

Time (h)

Co

nc

(pp

b)

O3 (obs)

O3 (ctm)

St. Mary's Ozone

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140

0 12 0 12 0 12

Time (h)

Co

nc

(pp

b)

O3 (obs)

O3 (ctm)Blacktown Ozone

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140

0 12 0 12 0 12

Time (h)

Co

nc

(pp

b)

O3 (obs)

O3 (ctm)

Richmond Ozone

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140

0 12 0 12 0 12

Time (h)

Co

nc

(pp

b)

O3 (obs)

O3 (ctm)

Eg: Syndey O3 Event Dec 1998

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Case Study of Smoke Episode in Melbourne, Australia

● Smoke episode

MELBOURNEMELBOURNE

AUSTRALIAAUSTRALIA

143.0 144.0 145.0 146.0 147.0

EASTING

-40.0

-39.0

-38.0

-37.0

-36.0

NO

RT

HIN

G

M ELBO U R N E

W AN G AR ATTA

BEN D IG O

BALLAR AT

W AR R AG U LG EELO N G

W O D O N G A

SH EPPAR TO N

C ASTLEM AIN E

BASS STR AIT

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Section 11 – Case Study of Episodes143.0 144.0 145.0 146.0 147.0

EASTIN G

-40 .0

-39.0

-38.0

-37.0

-36.0

NO

RT

HIN

G

M ELBO U R N E

W AN G AR ATTA

BEN D IG O

BALLAR AT


W O D O N G A

SH EPPAR TO N

C ASTLEM AIN E

BASS STR AIT

H O U R 12 11 JAN U AR Y 2001

143.0 144.0 145.0 146.0 147.0

EASTIN G

-40 .0

-39.0

-38.0

-37.0

-36.0

NO

RT

HIN

G

M ELBO U R N E

W AN G AR ATTA

BEN D IG O

BALLAR AT


W O D O N G A

SH EPPAR TO N

C ASTLEM AIN E

BASS STR AIT

H O U R 17 11 JAN U AR Y 2001

143.0 144.0 145.0 146.0 147.0

EASTIN G

-40 .0

-39.0

-38.0

-37.0

-36.0

NO

RT

HIN

G

M ELBO U R N E

W AN G AR ATTA

BEN D IG O

BALLAR AT


W O D O N G A

SH EPPAR TO N

C ASTLEM AIN E

BASS STR AIT

H O U R 0 12 JAN U AR Y 2001

143.0 144.0 145.0 146.0 147.0

EASTIN G

-40 .0

-39.0

-38.0

-37.0

-36.0

NO

RT

HIN

G

M ELBO U R N E

W AN G AR ATTA

BEN D IG O

BALLAR AT


W O D O N G A

SH EPPAR TO N

C ASTLEM AIN E

BASS STR AIT

H O U R 2 12 JAN U AR Y 2001

143.0 144.0 145.0 146.0 147.0

EASTIN G

-40 .0

-39.0

-38.0

-37.0

-36.0

NO

RT

HIN

G

M ELBO U R N E

W AN G AR ATTA

BEN D IG O

BALLAR AT


W O D O N G A

SH EPPAR TO N

C ASTLEM AIN E

BASS STR AIT

H O U R 6 12 JAN U AR Y 2001

143.0 144.0 145.0 146.0 147.0

EASTIN G

-40 .0

-39.0

-38.0

-37.0

-36.0

NO

RT

HIN

G

M ELBO U R N E

W AN G AR ATTA

BEN D IG O

BALLAR AT


W O D O N G A

SH EPPAR TO N

C ASTLEM AIN E

BASS STR AIT

H O U R 11 12 JAN U AR Y 2001


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Visible satellite image and modeled smoke

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● Select a few air quality episodes to study– Include ramp-up and cleanout days

● Review locations, magnitude, and duration of poor air quality

● Review surface and upper-air weather patterns● Create backward trajectories to estimate transport● Estimate upwind air quality to quantify local versus

background contributions ● Review the temperature soundings to estimate

vertical mixing● Summarize the important processes that produced

the episode

section 11 case studies of episodes

Documents