evaluation of ragweed forecasting in tulsa
DESCRIPTION
EVALUATION OF RAGWEED FORECASTING IN TULSA. Estelle Levetin, PhD The University of Tulsa. Ambrosia Pollen. Most important pollen allergen in N.A. In Tulsa area, cumulative Ambrosia pollen is first or second in terms of yearly abundance - PowerPoint PPT PresentationTRANSCRIPT
EVALUATION OF RAGWEED EVALUATION OF RAGWEED FORECASTING IN TULSAFORECASTING IN TULSA
Estelle Levetin, PhDThe University of Tulsa
Ambrosia Pollen
• Most important pollen allergen in N.A.
• In Tulsa area, cumulative Ambrosia pollen is first or second in terms of yearly abundance
• The ability to accurately predict day to day pollen levels could provide important benefit to sensitive individuals either by avoidance or by taking prophylactic medication
Stand of Ambrosia trifida along the east bank of the Arkansas River
Flowering in Ragweed
• Controlled by photoperiod• Pollination is the same time each year at a
given location unless stressful climatic conditions influence growth and reproduction in the plants.
• Once pollination begins, pollen release and atmospheric pollen concentrations are influenced by meteorological conditions.
Pollen Forecasts from TU
• Multiple regression models• Empirical model for mountain cedar
pollen release coupled with HY-SPLIT dispersion model
• Development of ragweed forecasts– Empirical Model– Ragweed Pollen Forecaster (computer
software) generated by 6 students from Dept of Computer Science (Cyber Corp)
Air Sampling
• Burkard Spore Trap has been used for air sampling in Tulsa since Dec. 1986
• Ragweed data from 1987 to 2001 was used to determine pollen season characteristics– Start date - 5% of season
total)– End date – 95% of season
total– Typical peak date
Five-Day Running Mean of Ambrosia Levels in the Tulsa Atmosphere 1987-2001
0
100
200
300
400
500
600
700
8/15 8/29 9/12 9/26 10/10 10/24
Po
llen
gra
ins
/m3
Five-Day Running Mean of Ambrosia Levels in the Tulsa Atmosphere 1987-2001
0
100
200
300
400
500
600
700
8/15 8/29 9/12 9/26 10/10 10/24
Po
llen
gra
ins
/m3
Pollen Season Characteristics
• Mean start date (5% of season total) – 27 Aug
• Mean end date (95% of season total) – 11 Oct
• Mean peak date – 10 Sep
Empirical Model
• Pollen concentrations compared with data from the National Weather Service to determine the effects of meteorological conditions on airborne pollen levels
• Empirical model was developed based on phenology and the weather forecast
• NGM-MOS 60 hour forecasts were used • Model was used to generate pollen forecasts for
the 2002 and 2003 ragweed seasons• Comparison with the atmospheric ragweed
pollen concentrations was used to evaluate the model
What conditions trigger pollen entrainment?
• No rain• Sunshine• Low humidity (below 75%)?• Moderate to high wind speeds• Afternoon temperatures below 95oF• Morning temperatures above 65oF• Phenological phase
Low Moderate High Very High
NAB*Percentile 0-50th 50-75th 75-99th >99th
NAB Concen 0-9 10-49 50-499 >500
Tulsa Concen 0-129 129-284 285-613 >613
1994 AAAAI Pollen and
Spore Report
Percentile 0-50th 50-75th 75-90th >90th
Tulsa Concen 0-129 129-284 285-410 >411
Tulsa ModelPercentile Goal 0-25th 25-50th 50-95th >95th
Actual Percentile 0-27th 27-47th 47-95th >95th
Concentration 0-49 50-99 100-489 >490
*Burge, H.A. 1992. Monitoring for Airborne Allergens. Annals of Allergy, 69: 9-18
What are Low, Moderate, High, and Very High Values?
Phenology Factor
0
1
2
3
4
5
6 0.0 to 0.49 - low0.5 to 0.99 - mod1.0 to 4.89 - high>4.90 - very high
Phenology Factor
0
1
2
3
4
5
6 0.0 to 0.49 - low0.5 to 0.99 - mod1.0 to 4.89 - high>4.90 - very high
Forecasting Model• Phenology Factor (PF) – based on day in the pollen
season and 15 year mean concentration (Range 1 to 6)• Metereological forecasts from NGM-MOS 60 hr forecast
R – forecast of rain (- variable amount) T – temp outside optimum range (morning temperature < 65
F or afternoon temperature > 95 F) (- variable amount) RH – forecast of noon relative humidity >75% (-1)W-sp – wind speeds >15 mph (+1)W-dir – wind from N - Aug 15-31 or wind from S - Oct 1-31
(+1)Pre – Preseason weather – hot, dry July and August (-1)
Forecast = PF – R – T – RH + W-sp + W-dir – Pre Forecast = PF – R – T – RH + W-sp + W-dir – Pre
2002 Average Daily Ambrosia Concentration
0
200
400
600
800
1000
1200
14008/
1/20
02
8/8/
2002
8/15
/200
2
8/22
/200
2
8/29
/200
2
9/5/
2002
9/12
/200
2
9/19
/200
2
9/26
/200
2
10/3
/200
2
10/1
0/20
02
10/1
7/20
02
10/2
4/20
02
10/3
1/20
02
Po
llen
gra
ins/
m3
2002 Average Daily Ambrosia Concentration
0
200
400
600
800
1000
1200
14008/
1/20
02
8/8/
2002
8/15
/200
2
8/22
/200
2
8/29
/200
2
9/5/
2002
9/12
/200
2
9/19
/200
2
9/26
/200
2
10/3
/200
2
10/1
0/20
02
10/1
7/20
02
10/2
4/20
02
10/3
1/20
02
Po
llen
gra
ins/
m3
Comparison of 2002 Ambrosia Pollen Concentration with Pollen Forecast
0
200
400
600
800
1000
1200
1400
Pol
len
grai
ns/m
3
LOW LOW/MOD MOD MOD/HIGH HIGH HIGH/VERY
Comparison of 2002 Ambrosia Pollen Concentration with Pollen Forecast
0
200
400
600
800
1000
1200
1400
Pol
len
grai
ns/m
3
LOW LOW/MOD MOD MOD/HIGH HIGH HIGH/VERY
2003 Average Daily Ambrosia Concentration
0
200
400
600
800
1000
1200
1400
Pol
len
grai
ns/m
3
2003 Average Daily Ambrosia Concentration
0
200
400
600
800
1000
1200
1400
Pol
len
grai
ns/m
3
Comparison of 2003 Ambrosia Pollen Concentrations with Pollen Forecast
0
100
200
300
400
500
600
Polle
n gr
ains
/m3
LOW LOW/MOD MOD MOD/HIGH HIGH HIGH/VERY VERY
Comparison of 2003 Ambrosia Pollen Concentrations with Pollen Forecast
0
100
200
300
400
500
600
Polle
n gr
ains
/m3
LOW LOW/MOD MOD MOD/HIGH HIGH HIGH/VERY VERY
Mean Airborne Ambrosia Pollen Concentration at Each Predicted Forecast Level
0
50
100
150
200
250
300
350
400
450
Po
llen
gra
ins/
m3
LOW LOW-MOD MOD MOD-HIGH HIGH HIGH-VERY VERY
Mean Airborne Ambrosia Pollen Concentration at Each Predicted Forecast Level
0
50
100
150
200
250
300
350
400
450
Po
llen
gra
ins/
m3
LOW LOW-MOD MOD MOD-HIGH HIGH HIGH-VERY VERY
Forecast Pollen Level
NAB Pollen Categories
Low Moderate High Very High
Number of Days
LOW 28 9 3
LOW TO MODERATE 11 16 7
MODERATE 2 3 7
MODERATE TO HIGH 15
HIGH 16 1
HIGH TO VERY HIGH 14 2
VERY HIGH 5 1
Ragweed Pollen Forecaster
Comparison of 2003 Pollen Concentration with Computer Generated Forecast
0
100
200
300
400
500
600
Po
llen
gra
ins/
m3
Low Moderate High Very High
Computer Program Evaluation
• Correct forecast 34 days (49%)• Incorrect forecast 13 days (19%)• No forecast data 23 days (32%)
– For the 47 days with data: 72% correct
Conclusions
• Empirical model accurately predicted the pollen level on 84% of the days during the 2002 and 2003 ragweed seasons (74% using NAB levels)
• Computer program needs more work• Pollen forecasts are only as accurate as the
meteorological forecasts• More research is needed on the
– effects of RH and rain on pollen release and dispersal
– influence of pre-season meteorological conditions on the seasonal pollen potential
AcknowledgmentThe assistance of Claudia Owens, Shernell Surratt, and Christen Townsend in counting pollen is greatly appreciated.