forecasting ozone in treasure valley using cart
DESCRIPTION
Forecasting Ozone in Treasure Valley using CART. Idaho DEQ June 3, 2011. Ozone in Treasure Valley. Forecasting for AQI and CRB. Daily AQI forecast for public Daily AQI forecast for residential burning bans (AQITRANSCRIPT
Forecasting Ozone in Treasure Valley using CART
Idaho DEQJune 3, 2011
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Ozone in Treasure Valley
Ozone in Treasure Valley
0
20
40
60
80
100
2001
2002
2003
2004
2005
2006
2007
2008
Year
Ozo
ne
Co
nce
ntr
atio
n
(pp
b)
8hr max
4th Highest
3year Ave 4thHighest
Standard
2
Treasure Valley Ozone Monthly Statistics2001-2008
0
20
40
60
80
100
MAY JUN JUL AUG SEP
Month
Ozo
ne
(pp
b)
Month Average
Ave Month Max
Month Max
3
Forecasting for AQI and CRB
• Daily AQI forecast for public• Daily AQI forecast for residential burning bans (AQI<60
outdoor, AQI <74 all burns)• Forecast for Crop Residual Burning • Regional offices utilize AIRPACT, WRF data, apply various
methods for the forecasting • Need more reliable, easy to use tools
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CART Model
• Classification And Regression Tree (CART) is a statistical procedure designed to classify data into dissimilar groups.
• CART helps to develop a decision tree to predict pollutant concentrations based predictor variables that are well correlated with pollutant concentrations.
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Forecasting Methods
Methods Development Effort Operational Effort Accuracy
Persistency Low Low Low
Climatology Low-Moderate Low Low
Criteria Low-Moderate Low Low-Moderate
CART Moderate Low Moderate-high
Regression Moderate Moderate Moderate-high
Neural Networks Moderate-high Moderate Moderate-high
3-D Air Quality
Models
Very High Moderate-high Moderate-high
Phenomenological
/Intuition
High Moderate High
From Guidelines for Developing an Air Quality (Ozone and PM2.5) Forecasting Program. EPA-456/R-03-002 June 20036
Data
• Eight year ozone data (2001-2008)• Eight year meteorological data including
surface data and upper air data: temperature, wind, humidity, pressure, etc.
• WRF forecasting data
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Correlation TablePositive correlation
No correlation
Negative correlation
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G=Green 0-59ppbY=Yellow 60-75 ppbO=Orange 76-95ppbR=Red 96-115ppbP-Purple 116-374ppb
CART tree for Treasure Valley Ozone Forecasting (1)Observation Data: Year 2001-2008, May-Aug
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G=Green 0-59ppbY=Yellow 60-75 ppbO=Orange 76-95ppbR=Red 96-115ppbP-Purple 116-374ppb
CART tree for Treasure Valley Ozone Forecasting (2)Observation Data: Year 2001-2008, May-Aug
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Performance EvaluationTS Performance
Total days 79
Observed Green Days 59
Observed Yellow Days 20
forecasted Green 52
Forecasted G for G 48
Forecasted Yellow 21
Forecasted Y for G 4
Forecasted G for Y 4
Forecasted Y for Y 17
Accuracy of Green 81%
Accuracy for Yellow 85%
Over forecasting 7%
Under forecasting 20%11
Performance
Ozone Forecast for Treasure ValleyOzone season 2010
0.0300.0350.0400.0450.0500.0550.0600.0650.0700.0750.080
6/6/
2010
6/8/
2010
6/10
/201
0
6/12
/201
0
6/14
/201
0
6/16
/201
0
6/18
/201
0
6/20
/201
0
6/22
/201
0
6/24
/201
0
6/26
/201
0
6/28
/201
0
6/30
/201
0
7/2/
2010
7/4/
2010
7/6/
2010
7/8/
2010
7/10
/201
0
7/12
/201
0
7/14
/201
0
7/16
/201
0
7/18
/201
0
7/20
/201
0
7/22
/201
0
7/24
/201
0
7/26
/201
0
7/28
/201
0
7/30
/201
0
8/1/
2010
8/3/
2010
8/5/
2010
8/7/
2010
8/9/
2010
8/11
/201
0
8/13
/201
0
8/15
/201
0
8/17
/201
0
8/19
/201
0
8/21
/201
0
8/23
/201
0
8/25
/201
0
8/27
/201
0
8/29
/201
0
8/31
/201
0
9/2/
2010
Date
Ozo
ne
(p
pm
)
Obs Max 8hr Max TS Forecast
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Source of Errors
• Small changes near the split point may end larger errors.
• Bias in the meteorological forecast.• Emission changes. e.g. Holidays, economy driven
sources.• Boundary conditions. e.g. Stratosphere intrusion (ST)
due to stratosphere-troposphere exchange (STE); long range transport.
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An unusual Ozone Episode in May 2011Graphs From AIRPACT
Conditions on May 15, 2011 in Treasure Valley:A cold front was reaching the areaMax temperature ~ 53°F, breezy, rainMax 8hour average O3 reached 63ppb in early afternoon, the highest in the month.
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Monthly average relative humidity was 26.7%Average 6 year Relative humidity in May is 38.4%. (average from 10:00am-6:00pm)
Warm (~80’s °F) and Dry
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Weekend Effect
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CART- Limitations
• Requires large set of data, a modest amount of expertise and effort to develop.
• Small changes in predictor variables may produce large changes in the predictions.
• Does not predict unusual events.• Requires periodic updates due to emission
and land use changes.
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Future Work
• Improve the model for Boise • Experiment for Coeur d’Alene• Explore more parameters• Study for unusual events.
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