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AREP
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Section 11
Case Studies of Episodes
What is a Case Study?
How to Conduct Case Studies
Examples
AREP
GURME
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
Section 11 – Case Study of Episodes
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AREP
GURME
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
Section 11 – Case Study of Episodes
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AREP
GURME
Examples
Each 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
Section 11 – Case Study of Episodes
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AREP
GURME
Case Study of PM10 Episode in
Cairo, Egypt
●
●
●
●
Location and background
Air quality conditions
Weather situation
Summary of episode (air quality and
meteorology)
Section 11 – Case Study of Episodes
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GURME
Location – Cairo, Egypt
Cairo
Section 11 – Case Study of Episodes
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AREP
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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).
Section 11 – Case Study of Episodes
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AREP
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Weather Situation (1 of 6)
Surface and upper-air weather patterns
H
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
Section 11 – Case Study of Episodes
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AREP
GURME
Weather Situation (2 of 6)
Surface and upper-air weather patterns
L
Light
northerly
winds
Weak trough
just passed
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
Section 11 – Case Study of Episodes
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GURME
Weather Situation (3 of 6)
Surface and upper-air weather patterns
Moderate
northerly
winds
Strong trough
just passed
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
Section 11 – Case Study of Episodes
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GURME
Weather Situation (4 of 6)
Backward trajectories to estimate transport
32
20-Oct
21-Oct
Latitude (degrees)
31.5
22-Oct
23-Oct
24-Oct
25-Oct
21
25
22
31
20
24
23
30.5
Short transport
on high PM day
30
29.5
29.5
30
30.5
31
Longitude (degrees)
31.5
32
32.5
12-hr backward trajectories ending in Cairo at 1400 LT each day October 20 to 25, 1999.
Section 11 – Case Study of Episodes
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AREP
GURME
Weather Situation (5 of 6)
Upper-air nighttime soundings to estimate
vertical mixing
3000
20-Oct
21-Oct
22-Oct
23-Oct
24-Oct
25-Oct
Height (m)
2500
2000
Warming
1500
25
20
1000
21
23
24
22
Strong
Inversion
500
0
10
15
20
25
30
Temperature (ºC)
0200 LT temperature soundings taken at Helwan from October 20 to 25, 1999.
Section 11 – Case Study of Episodes
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AREP
GURME
Weather Situation (6 of 6)
Upper-air daytime soundings to estimate
vertical mixing
3000
20-Oct
21-Oct
22-Oct
23-Oct
24-Oct
25-Oct
2500
Height (m)
2000
Warming
24
1500
21
22
20
1000
23
25
500
0
10
15
20
25
30
Temperature (ºC)
1400 LT temperature soundings taken at Helwan from October 20 to 25, 1999.
Section 11 – Case Study of Episodes
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Summary of Episode
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
Section 11 – Case Study of Episodes
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AREP
GURME
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
Section 11 – Case Study of Episodes
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AREP
GURME
Case Study of Ozone Episode
●
●
●
●
Location and background
Air quality conditions
Weather situation
Summary of episode (air quality and
meteorology)
Section 11 – Case Study of Episodes
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AREP
GURME
Case Study of Ozone Episode


Youngstown, Ohio, USA
Summer 2002
8 July 2002 Episode
160
160
140
140
Maximum AQI
Maximum AQI
9-11 June 2002 Episode
120
100
80
60
40
120
100
80
60
40
20
20
0
0
10
ul
-J
l
Ju
9-
l
Ju
8-
l
Ju
7-
un
-J
un
-J
un
-J
un
-J
l
Ju
6-
13
12
11
10
n
Ju
9-
n
Ju
8-
n
Ju
7-
Section 11 – Case Study of Episodes
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AREP
GURME
Case Study of Ozone Episode
9-11 June 2002 Episode
160
Youngstown
Regional 8-hr O3 Maximum
Maximum AQI
140
120
100
80
60
40
20
0
500-mb Heights
* *
* * *
* *
24-hr Backward Trajectory
Surface Pressure (msl)
L
H
H
L
L
L
H
H
HH
13
Jun 11
07
10
12thth 12:00
12:00 pm
pm EST
EST
Jun
09
08
L
H
HH H
Section 11 – Case Study of Episodes
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AREP
GURME
Case Study of Ozone Episode
8 July 2002 Episode
160
*
Maximum AQI
140
120
Youngstown
Regional 8-hr O3 Maximum
100
80
*
60
*
40
20
0
*
10
l
u
-J
l
Ju
9-
l
Ju
8-
l
Ju
7-
l
Ju
6-
500-mb Heights
*
24-hr Backward Trajectory
Surface Pressure (msl)
L
H
H
H
H
H
Section 11 – Case Study of Episodes
Jul
Jul 08
07
09
10
06thth 12:00
12:00 pm
pm EST
EST
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GURME
Summary of Ozone 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
Section 11 – Case Study of Episodes
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AREP
GURME
Case Study of Ozone Episode in
Sydney, Australia
Ozone episode
MUSWELLBROOK
6400
NEWCASTLE
6350
NORTHING (km)
●
AUSTRALIA
6300
LITHGOW
PENRITH
SYDNEY
6250
PICTON
6200
WOLLONGONG
SYDNEY
6150
200
250
300
350
400
450
500
EASTING (km)
Section 11 – Case Study of Episodes
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Eg: Syndey O3 Event Dec 1998
AREP
GURME
Richmond Ozone
140
O3 (obs)
120
O3 (ctm)
100
RICH
80
60
O3 (obs)
120
VYNE
40
20
St. Mary's Ozone
140
0
0
O3 (ctm)
O3 (obs)
Conc (ppb)
12120
0
12
Time (h)
100
0
12
O3 (ctm)
100
80
60
40
O3 (obs)
80
120
60
100
40
20
-33.8
Blacktown Ozone
140
Conc (ppb)
-33.7
LATITUDE (degrees)
Lindfield Ozone
140
Conc (ppb)
Conc (ppb)
-33.6
0
0
12
0
12
Time (h)
0
12
0
BLAC
80
60
ST.M
20
12
0
12
Time (h)
LIND
WSTM
40
0
20
O3 (ctm)
12
0
Bringely Ozone
140
0
12
0
O3 (obs)
Conc (ppb)
120
12
Time (h)
0
12
ROZE
O3 (ctm)
LIDC
100
-33.9
80
Liverpool Ozone
BRIN
60
140
40
LIVE
120
Conc (ppb)
20
0
0
12
0
12
Time (h)
-34.0
0
12
EARL
O3 (obs)
RAND
O3 (ctm)
100
80
60
TASMAN
SEA
40
20
CAMD
O3 (obs)
120
0
100
60
40
20
-34.1
150.5
150.6
150.7
0
0
12
0
12
Time (h)
0
12
12
0
12
Time (h)
0
12
O3 (obs)
150.8
120
100
150.9
O3 (ctm)
80
151.0
151.1
LONGITUDE (degrees)
60
40
O3 (obs)
120
O3 (ctm)
Bargo Ozone
140
Conc (ppb)
80
140
CAMP
O3 (ctm)
Woolooware Ozone
WOOL
0
Conc (ppb)
Camden Ozone
140
Conc (ppb)
0
100
80
60
40
20
151.2
151.3
151.4
0
0
12
0
12
Time (h)
0
12
Section 11 – Case Study of Episodes
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0
0
12
0
12
Time (h)
0
12
22
AREP
GURME
Case Study of Smoke Episode in
Melbourne, Australia
Smoke episode
-36.0
WODONGA
WANGARATTA
SHEPPARTON
BENDIGO
-37.0
AUSTRALIA
NORTHING
●
CASTLEMAINE
BALLARAT
MELBOURNE
-38.0
GEELONG
WARRAGUL
-39.0
BASS STRAIT
MELBOURNE
-40.0
143.0
144.0
145.0
146.0
147.0
EASTING
Section 11 – Case Study of Episodes
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Case Study of Smoke Episode in
Melbourne, Australia
HOUR 11
1212
17
0
2
6
11JANUARY
12
JANUARY2001
2001
-36.0
WODONGA
WANGARATTA
SHEPPARTON
BENDIGO
-37.0
NORTHING
AREP
GURME
CASTLEMAINE
BALLARAT
MELBOURNE
-38.0
GEELONG
WARRAGUL
-39.0
BASS STRAIT
-40.0
143.0
Section 11 – Case Study of Episodes
144.0
145.0
EASTING
146.0
147.0
24
AREP
GURME
Case Study of Smoke Episode in
Melbourne, Australia
Visible satellite image and modeled smoke
Section 11 – Case Study of Episodes
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AREP
GURME
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
Section 11 – Case Study of Episodes
26