CRAZ Ozone Analysis

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

Primary Emissions

Secondary Pollutants

CASA Action Levels

Source: Alberta Environment, Particulate Matter and Ozone Assessment for Alberta 2001- 2007

Data and ModelsNine 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 2008 2007 2006 2005 2004 2003 2002 2001

12-Apr-09

12-May-07 12-May-06

17-May-04 09-Apr-03 14-Apr-02 13-May-01

18-Apr-09

02-Jun-07 23-Jul-06

03-Jun-04 25-May-03 13-Jun-02 26-May-01

01-May-09

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 back-trajectories.

• Long-range

• Local - 1

• Local - 2

• Mixed range

Summary TableWeather Pattern

Long Range (25/48)

Local Transport

(14/48)

Mixed Range (10/48)

Direction of Coming Air Mass

Maximum Temp.

(οC)

Daily Mean Wind Speed

(m/s)

Pressure System Type

Low Medium High

DM-P (2 1/48)

Apr 18, 2009 May 27, 2009

W N

W W

W W

13.8 20.2

5.4 5.4

High High

Jun 3, 2009 ALL ALL N,NW 22.2 2.7 High Jul 25, 2009 ALL ALL SW 28.8 2.4 High

Aug 27, 2009 W SW SW 24.7 2.3 High

May 11, 2007 Sep 1,2009 SE

W SE W

S SW

27.6 21.7

2.9 2.6

High High

Jun, 2, 2007 NE SW SW 26.5 2.9 High Jun, 4, 2007 NE W S 24.1 5.1 High Jul, 23, 2006 ALL ALL SW 31.1 3.3 High Sep 6, 2006 ALL ALL SW 26.9 2.9 High

May, 17, 2004

NNW N N 18.2 2.7 High

Jun, 3, 2004 W W W 21.0 2.8 High Jun, 4, 2004 W,SW SW SW 24.3 3.3 High

Aug 9, 2003 Jul, 23, 2003 SW

SW SW SE

SW NE

29.8 25.4

3.6 3.8

High High

Jun 13, 2002 N N NW 23.7 1.9 High Jun 22, 2002 ALL S SW 26.1 4.1 High Jul 16, 2002 W SW S,SW 28.8 3.3 High May, 26, 2001 NE E W 21.6 3.8 High Aug, 12, 2001 N,NW

NW

W

30.4

2.5

High

DM-T (11/48)

Apr 12, 2009

May 12, 2007

May 12, 2006 May 29, 2003 July 22, 2003 Jul 18, 2002

May 13, 2001 Jul 24, 2003

May 25, 2009

May 24,2009

Aug 3, 2007

W S

ALL W W

SW S,SW SW SW W W

W W W W W SW SW SW SW SW SW

W W W

SW W

SW SW SW SW SW SW

14.2 21.6 19.3 23.1 27.0 16.3 22.4 31.0 29.9 22.7 22.8

3.9 2.7 4.5 4.2 4.8 6.8 5.7 2.9 4.1 4.8 6.3

low low low low low low low low low low low

DP (5/48)

May 1, 2009 N,NW N,NW NW 13.2 3.8 High May 23, 2009 NW SW W 20.4 4.3 High

May, 25, 2003 S SW SW 26.1 3.6 High Aug, 8, 2003 ALL ALL SW 23.4 2.9 High

Jun, 21, 2002 W W W 24.4 1.9 High DT

(7/48)

Aug, 8, 2006 Aug, 13, 2003 Aug, 14, 2003

Jul, 13, 2002 Jul, 17, 2002 Jul, 15, 2007

Aug, 15, 2003

SW SS SW 31.8 4.2 Low SW SW ALL SW SW S

SW SW SW SW SW S

NW SW S S

SW SW

28.4 29.1 32.4 34.0 32.8 28.7

3.8 3.2 3.9 3.3 3.2 3.1

low Low low Low low Low

TR

(4/48) Apr, 9, 2003 SW SW W 15.1 5.8 High to Low Jun, 30, 2003 SW SW SW 28.0 5.7 Low to High Apr, 14, 2002 W,SW NW NW 16.6 9.1 Low to High May, 29, 2001 SW SW W 14.4 7.1 Low to High

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

%

SCC DM-P DM-T DP DT TR Total Long-Range 5 8 2 6 4 25

Local 10 1 1 1 13 Mixed-Range 6 2 2 10

Total 21 11 5 7 4 48

67%

10%

15%

8%

• 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

Air Mass/ Air Quality

• 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

Temperature

SCC Daily Maximum Temperature

> 18οC

Daily Maximum Temperature

< 18οC

Total

Long-Range 19 6 25 Local 13 13

Mixed-Range 8 2 10 Total 40 8 48

Ozone Isopleths

NOx Limited

VOC 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, [email protected]