CRAZ Ozone Analysis
Xin Qiu, Ph.D., ACM, EP
May 3rd, 2011
Objectives
• Perform an analysis of the factors
contributing to high ozone days in CRAZ
• Identify and assess the drivers for local
and regional ozone formation
• Understand ozone formation mechanism
as NOx-Limited vs VOC-Limited
• Provide additional support to identify
“back-out” situations
AQ Issues
NOx
O3
Primary
Emissions
VOCs
NOX
SO2
NH3
Secondary
Pollutants
PM2.5
CASA Action Levels
Source: Alberta Environment, Particulate Matter and Ozone Assessment for Alberta 2001- 2007
Data and Models
Nine Years of data (2001 -2009)
• Meteorological Data
– The National Climatic Data Center archives of surface
and upper air data in North America
• Air Quality Data
– CASA measurements of ambient concentrations of ozone
in/out of CRAZ
Tools
• HYSPLIT Back Trajectory Model
• Synoptic Classification
• Statistical Analysis
CRAZ Area &
Its Monitoring Stations
CRAZ High Ozone Days 2001 – 2009
2009
12-Apr-09
2008
2007
12-May-07
2006
12-May-06
18-Apr-09
02-Jun-07
01-May-09
2005
2004
17-May-04
2003
09-Apr-03
2002
14-Apr-02
2001
13-May-01
23-Jul-06
03-Jun-04
25-May-03
13-Jun-02
26-May-01
04-Jun-07
08-Aug-06
04-Jun-04
29-May-03
21-Jun-02
29-May-01
23-May-09
15-Jul-07
06-Sep-06
30-Jun-03
22-Jun-02
12-Aug-01
24-May-09
03-Aug-07
22-Jul-03
13-Jul-02
25-May-09
23-Jul-03
16-Jul-02
03-Jun-09
24-Jul-03
17-Jul-02
25-Jul-09
08-Aug-03
18-Jul-02
27-Aug-09
09-Aug-03
01-Sep-09
13-Aug-03
14-Aug-03
15-Aug-03
Threshold: O3 8-hr mean > 58 ppb
Back Trajectory Model
• The Hybrid Single Particle Lagrangian
Integrated Trajectory (HYSPLIT) model
developed by the National Oceanic and
Atmospheric Administration (NOAA)
• By incorporating receptor location
coordinates, altitudes, run time, and
meteorological data, the model provides back
trajectory history from the receptor to the
source over a given period of time.
Definitions
• Long-range: Clear stretch of trajectories from one direction;
high ozone due to long-range transport from emission
sources outside of Alberta. This is the case can be “backed
out”.
• Local: trajectories are mostly localized, particularly at low
and middle altitude. High ozone mainly due to local
emissions and the Management Plan should be in place.
• Mixed-Range: trajectories are slightly beyond local (CRAZ)
area, or the transport within province (e.g., transport from
Edmonton). This is usually a complicated situation and we
further look into case by case.
• Dominated Wind Direction: defined as the direction where
air mass moves from according to the majority of backtrajectories.
• Long-range
• Local - 1
• Local - 2
• Mixed range
Summary Table
Weather
Pattern
Long Range
(25/48)
DM-P
(2 1/48)
Apr 18, 2009
May 27, 2009
Local
Transport
(14/48)
Mixed Range
(10/48)
Pressure
System Type
Medium
High
W
W
ALL
ALL
SW
SE
W
SW
W
ALL
ALL
W
W
N,NW
SW
SW
S
SW
SW
S
SW
SW
13.8
20.2
22.2
28.8
24.7
27.6
21.7
26.5
24.1
31.1
26.9
5.4
5.4
2.7
2.4
2.3
2.9
2.6
2.9
5.1
3.3
2.9
High
High
High
High
High
High
High
High
High
High
High
NNW
N
N
18.2
2.7
High
W
W,SW
SW
SW
N
ALL
W
NE
N,NW
W
SW
SW
SE
N
S
SW
E
NW
W
SW
SW
NE
NW
SW
S,SW
W
W
21.0
24.3
29.8
25.4
23.7
26.1
28.8
21.6
30.4
2.8
3.3
3.6
3.8
1.9
4.1
3.3
3.8
2.5
High
High
High
High
High
High
High
High
High
Jul, 13, 2002
Jul, 17, 2002
Jul, 15, 2007
W
S
ALL
W
W
SW
S,SW
SW
SW
W
W
N,NW
NW
S
ALL
W
SW
SW
SW
ALL
SW
SW
S
W
W
W
W
W
SW
SW
SW
SW
SW
SW
N,NW
SW
SW
ALL
W
SS
SW
SW
SW
SW
SW
S
W
W
W
SW
W
SW
SW
SW
SW
SW
SW
NW
W
SW
SW
W
SW
NW
SW
S
S
SW
SW
14.2
21.6
19.3
23.1
27.0
16.3
22.4
31.0
29.9
22.7
22.8
13.2
20.4
26.1
23.4
24.4
31.8
28.4
29.1
32.4
34.0
32.8
28.7
3.9
2.7
4.5
4.2
4.8
6.8
5.7
2.9
4.1
4.8
6.3
3.8
4.3
3.6
2.9
1.9
4.2
3.8
3.2
3.9
3.3
3.2
3.1
low
low
low
low
low
low
low
low
low
low
low
High
High
High
High
High
Low
low
Low
low
Low
low
Low
Apr, 9, 2003
SW
SW
W
15.1
5.8
High to Low
Jun, 30, 2003
Apr, 14, 2002
May, 29, 2001
SW
W,SW
SW
SW
NW
SW
SW
NW
W
28.0
16.6
14.4
5.7
9.1
7.1
Low to High
Low to High
Low to High
Sep 1,2009
May 11, 2007
Jun, 2, 2007
Jun, 4, 2007
Jul, 23, 2006
Sep 6, 2006
May, 17,
2004
Jun, 3, 2004
Jun, 4, 2004
Jul, 23, 2003
Aug 9, 2003
Jun 13, 2002
Jun 22, 2002
Jul 16, 2002
May, 26, 2001
Aug, 12, 2001
Apr 12, 2009
May 24,2009
May 25, 2009
May 12, 2007
Aug 3, 2007
May 12, 2006
May 29, 2003
July 22, 2003
Jul 18, 2002
May 13, 2001
Jul 24, 2003
DP
(5/48)
May 1, 2009
May 23, 2009
May, 25, 2003
Aug, 8, 2003
Jun, 21, 2002
Aug, 8, 2006
Aug, 13, 2003
Aug, 14, 2003
Aug, 15, 2003
TR
(4/48)
Daily Mean
Wind Speed
(m/s)
W
N
ALL
ALL
W
SE
W
NE
NE
ALL
ALL
Aug 27, 2009
DT
(7/48)
Maximum
Temp.
(οC)
Low
Jun 3, 2009
Jul 25, 2009
DM-T
(11/48)
Direction of Coming Air Mass
The Concept of Air Mass
• What is an air mass?
• How is it related to basic meteorological
parameters (temperature, pressure, winds,
etc.)?
• How is it different from analysis of basic
meteorological parameters?
– Source
– Duration
– Spatial coverage
Weather Pattern
DM-P
Synoptic Air Mass Types**
•
•
•
•
•
•
•
•
Dry Polar (DP): Low temperature, clear sky, stable and dry air. Air
mass is generally advected from cold north polar regions.
Dry Tropical (DT): The hottest and driest weather condition. Air is
either advected from the USA, or produced by rapidly descending air.
Dry Moderate Polar (DM-P): Mild and dry, as modified dry polar air
from the anticyclone system that dominates Alberta.
Dry Moderate Tropical (DM-T): Mild and dry, and usually as modified
from tropical air mass originating from the United States.
Transitional (TR): During these days one weather type yields to
another.
Moist Tropical (MT): Hot and humid. Typically found in summer warm
sectors of mid-latitude cyclones or in a return flow of an anticyclone.
Moist Moderate (MM): Mild, cloudy, and unstable. Generally close to a
warm front, as modified moist polar or moist tropical air.
Moist Polar (MP): Cool, humid, overcast. Winds are usually from the
north or northwest.
**Sheridan Spatial Synoptic Classification system (2001)
(http://sheridan.geog.kent.edu/ssc.html)
Frequencies in Calgary
%
8%
15%
67%
10%
SCC
Long-Range
Local
Mixed-Range
Total
DM-P
5
10
6
21
DM-T
8
1
2
11
DP
2
1
2
5
DT
6
1
TR
4
7
4
Total
25
13
10
48
Air Mass/ Air Quality
• Dry Moderate (DM), Dry Tropical (DT), and
the Dry Polar (DP), are always among the top
three circulation patterns associated with the
high Ozone concentrations.
• DM shows highest frequency associated with
ozone concentrations.
• DM has westerly or southwesterly flow
• No high ozone event found in MT, MM &MP
• Local and Mixed-range mostly associated
with DM
Temperature
• 83% of total high ozone days were associated
with temperatures greater than 18οC
• 100% local high ozone events are associated
with temperature higher than 18οC
• 80% mixed-range high ozone events are
associated with temperature higher than 18οC
SCC
Long-Range
Local
Mixed-Range
Total
Daily Maximum
Temperature
> 18οC
19
13
8
40
Daily Maximum
Temperature
< 18οC
6
2
8
Total
25
13
10
48
Ozone Isopleths
VOC Limited
NOx Limited
NOx/VOC Ratios
1/8
NOx/VOC Ratios
• NOx/VOC ratios in Calgary were much
higher than in Red Deer;
• NOx/VOC ratios in Calgary were greater
than 1/8,  VOC-Limited
• Most NOx/VOC ratios in Red Deer were
less than 1/8  NOx-Limited
• Larger variations in NOx/VOC ratios
were found in Calgary than in Red Deer
Summary - 1
• Long-range transport: 52%
(”back-out”)
• Local: 27%
• Mixed range: 21%
Summary - 2
• More than 66% of the high ozone days
occurred under DM-T and DM-P weather
patterns, with 40% long-range transport, 35%
local and 25% mixed range accounted for
35% and 25%.
• Local transport is strongly related to DM-P
weather patterns
• Mixed-range transport is mostly related to DM
weather types. Required further investigation.
Summary -3
• CRAZ has both VOC-limited and NOx-limited
ozone formation regimes.
• In urban area (City of Calgary), a VOC-limited
mechanism dominated mostly
• In rural area, it’s likely a NOx-limited
mechanism
• In suburban area, it’s depended upon air
mass and urban plume (uncertainty remains)
Uncertainties/Limitations
• HYSPLIT has limitations
• Only 3 CRAZ monitoring stations & located in
urban area
• Anthropogenic emissions were not included
in the analysis
• Biogenic VOC emissions were not included in
the analysis
• Lack of data to identify ozone formation in
sub-urban area
Dr. Xin Qiu, EP, ACM
416-320-1363
xinq@novusenv.com