AREPGURME
Section 11Case Studies of Episodes
What is a Case Study?
How to Conduct Case Studies
Examples
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AREPGURME
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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Section 11 – Case Study of Episodes
How to Conduct Case Studies
● 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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Section 11 – Case Study of Episodes
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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Section 11 – Case Study of Episodes
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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Section 11 – Case Study of Episodes
Location – Cairo, Egypt
Cairo
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Section 11 – Case Study of Episodes
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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Section 11 – Case Study of Episodes
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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Section 11 – Case Study of Episodes
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
Surface and upper-air weather patterns
Weak trough just passed
L
Light northerly
winds
Weather Situation (2 of 6)
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Section 11 – Case Study of Episodes
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
Surface and upper-air weather patterns
Strong trough just passed
Moderatenortherly
winds
Weather Situation (3 of 6)
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Section 11 – Case Study of Episodes
12-hr backward trajectories ending in Cairo at 1400 LT each day October 20 to 25, 1999.
Backward trajectories to estimate transport
Weather Situation (4 of 6)
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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Section 11 – Case Study of Episodes
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
Weather Situation (5 of 6)
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Section 11 – Case Study of Episodes
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
Weather Situation (6 of 6)
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Section 11 – Case Study of Episodes
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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Section 11 – Case Study of Episodes
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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Section 11 – Case Study of Episodes
Case Study of Ozone Episode
● Location and background● Air quality conditions● Weather situation● Summary of episode (air quality and
meteorology)
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Section 11 – Case Study of Episodes
Case Study of Ozone Episode
Youngstown, Ohio, USA Summer 2002
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Section 11 – Case Study of Episodes
500-mb Heights Surface Pressure (msl) 24-hr Backward Trajectory
Jun 07th 12:00 pm EST
H
Jun 08th 12:00 pm EST
H
H
Jun 09th 12:00 pm EST
HH
L
Jun 10th 12:00 pm EST
H
HH
Jun 11th 12:00 pm EST
HH
L
Jun 12th 12:00 pm EST
L L
Case Study of Ozone Episode9-11 June 2002 Episode
0
20
40
60
80
100
120
140
160
7-Jun8-Jun
9-Jun10-Jun
11-Jun
12-Jun
13-Jun
Ma
xim
um
AQ
I*
* **
**
YoungstownRegional 8-hr O3 Maximum
*
Jun 13th 12:00 pm EST
L
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Section 11 – Case Study of Episodes
Jul 06th 12:00 pm EST
H
Case Study of Ozone Episode
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
* *
*
Jul 07th 12:00 pm EST
H
**
YoungstownRegional 8-hr O3 Maximum
HH
Jul 08th 12:00 pm EST
L
Jul 09th 12:00 pm EST
H
Jul 10th 12:00 pm EST
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Section 11 – Case Study of Episodes
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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Section 11 – Case Study of Episodes
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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Section 11 – Case Study of Episodes
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
0
20
40
60
80
100
120
140
0 12 0 12 0 12
Time (h)
Co
nc
(pp
b)
O3 (obs)
O3 (ctm)
Woolooware Ozone
0
20
40
60
80
100
120
140
0 12 0 12 0 12
Time (h)C
on
c (p
pb
)
O3 (obs)
O3 (ctm)
Camden Ozone
0
20
40
60
80
100
120
140
0 12 0 12 0 12
Time (h)
Co
nc
(pp
b)
O3 (obs)
O3 (ctm)
Bargo Ozone
0
20
40
60
80
100
120
140
0 12 0 12 0 12
Time (h)
Co
nc
(pp
b)
O3 (obs)
O3 (ctm)
Bringely Ozone
0
20
40
60
80
100
120
140
0 12 0 12 0 12
Time (h)
Co
nc
(pp
b)
O3 (obs)
O3 (ctm)
Liverpool Ozone
0
20
40
60
80
100
120
140
0 12 0 12 0 12
Time (h)
Co
nc
(pp
b)
O3 (obs)
O3 (ctm)
St. Mary's Ozone
0
20
40
60
80
100
120
140
0 12 0 12 0 12
Time (h)
Co
nc
(pp
b)
O3 (obs)
O3 (ctm)Blacktown Ozone
0
20
40
60
80
100
120
140
0 12 0 12 0 12
Time (h)
Co
nc
(pp
b)
O3 (obs)
O3 (ctm)
Richmond Ozone
0
20
40
60
80
100
120
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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Section 11 – Case Study of Episodes
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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AREPGURME
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 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
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 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
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 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
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 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
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 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
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 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
H O U R 11 12 JAN U AR Y 2001
Case Study of Smoke Episode in Melbourne, Australia
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Section 11 – Case Study of Episodes
Case Study of Smoke Episode in Melbourne, Australia
Visible satellite image and modeled smoke
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AREPGURME
Section 11 – Case Study of Episodes
How to Conduct Case Studies
● 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