air quality forecast feedback: los angeles air basin · 2016. 9. 15. · sang-mi lee, ph.d and...

South Coast Air Quality Management District

Air Quality Forecast Feedback: Los Angeles Air Basin

NOAA Forecast Working Group Meeting September 15-16, 2016

Sang-Mi Lee, Ph.D and Scott Epstein, Ph.D

South Coast Air Quality Management District

21865 Copley Dr, Diamond Bar, CA 92886

South Coast Air Quality Management District

Overview

• 12 UTC cycle Forecast Products • Retrieved for Los Angeles Air Basin • 2nd day forecast variables were evaluated:

– Daily Max 8-hour Ozone – Average 24-hour PM2.5 – Meteorological variables (Wind Speed, Temperature and Humidity)

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South Coast Air Quality Management District

Performance Evaluation Zone

3

Los Angeles Downtown

Pacific Ocean

Redlands

South Coast Air Quality Management District

Daily Max 8-hour Ozone

4

South Coast Air Quality Management District

Average 24-hour PM2.5

5

PM2.5 measurements were made with automated Beta Attenuation Method samplers

South Coast Air Quality Management District

Daily Max 8-hour Ozone at Crestline

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South Coast Air Quality Management District

Daily Max 8-hour Ozone at Glendora

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South Coast Air Quality Management District

Month to Month Variation

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Daily Max 8-hour Ozone at Glendora: June & July 2016

South Coast Air Quality Management District

Performance Statistics by Month

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-40

-20

0

20

40

60

80

100

Daily

-Max

Mea

n Pr

ed.

Unp

aire

d [p

pb]

Daily

-Max

Mea

n O

bs.

[ppb

]Da

ily-M

ax B

ias E

rr.

Unp

aire

d [p

pb]

Daily

-Max

Gro

ss E

rr.

Unp

aire

d [p

pb]

Nor

m D

aily

-Max

Bia

sEr

r. U

npai

red

[%]

Nor

m D

aily

-Max

Gro

ssEr

r. U

npai

red

[%]

Peak

Pre

dict

ion

Accu

racy

Unp

aire

d[p

pb]

UrbanReceptor

UrbanReceptor

May Jun Jul

South Coast Air Quality Management District

Geographical Variation

10

-80

-60

-40

-20

0

20

40

60

80

100Da

ily-M

ax M

ean

Pred

.U

npai

red

[ppb

]

Daily

-Max

Mea

n O

bs.

[ppb

]

Daily

-Max

Bia

s Err

.U

npai

red

[ppb

]

Daily

-Max

Gro

ss E

rr.

Unp

aire

d [p

pb]

Nor

m D

aily

-Max

Bia

s Err

.U

npai

red

[%]

Nor

m D

aily

-Max

Gro

ss E

rr.

Unp

aire

d [%

]

Peak

Pre

dict

ion

Accu

racy

Unp

aire

d [p

pb]

Daily Max 8-hour O3

Coastal

UrbanSource

UrbanReceptor

Foothills

South Coast Air Quality Management District

METEOROLOGICAL FACTOR

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South Coast Air Quality Management District

Wind Speed Prediction Performance: Monthly

12

-60

-40

-20

0

20

40

60

80

May Jun Jul

[%]

Wind Speed Normalized Bias and Gross Error in "Urban Receptor"

South Coast Air Quality Management District

Wind Speed Prediction : Geographical Variation

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-80

-60

-40

-20

0

20

40

60

80

UrbanReceptor Foothills_UrbSrc Coastal

(%)

Wind Speed

South Coast Air Quality Management District

Anaheim and Crestline

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Wind Over Prediction Ozone under Prediction

Wind under

Prediction Ozone Over

Prediction

Wind Over Prediction Ozone under Prediction

Wind under

Prediction Ozone Over

Prediction

South Coast Air Quality Management District

NOAA VS. SOUTH COAST AQMD Spatial Grid resolution WRF Forecast vs. Hindcast Chemical mechanism > SCAQMD uses SAPRC07

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South Coast Air Quality Management District

NOAA vs. SCAQMD Predictions

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NOAA

SCAQMD

South Coast Air Quality Management District

NOAA vs. SCAQMD Predictions

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NOAA

SCAQMD

South Coast Air Quality Management District

NOAA vs. SCAQMD at Crestline site

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South Coast Air Quality Management District

Summary and Conclusions

• NOAA forecast still tends to under-predict high ozone episodes in the Basin especially urban receptor areas where the peak concentrations are recorded.

• The bias grows bigger in June and July. However, meteorological prediction does not show the same trend.

• The errors in ozone prediction do not correlate with wind prediction bias directly. (i.e. wind under prediction appeared in ozone under prediction)

• SCAQMD’s modeling product which has higher spatial resolution, improved WRF predictions, and SAPRC-07 chemical mechanism shows reasonably good performance to capture high ozone episodes and meteorology vs. chemistry correlation.

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