CMAQ Sensitivity Testing for the Eastern United States

Jeffrey W. Stehr

Department of Meteorology

University of Maryland

October 22, 2002

Durham, NC, Models-3 Users’ Workshop

Meteorology

THE SIMULATION:Meteorology:

• MM5 using Gayno-Seaman planetary boundary layer scheme

• 24 vertical levels, 12 km (202 x 199) nest inside a 36 km domain

• Analysis nudging to NCEP (Eta) reanalysis

• There are problems with MM5!!!

Meteorology: Modifying MM5

• University of Maryland (Zhang & Zheng) has modified the Blackadar boundary layer scheme to achieve better surface winds and temperatures

• Other PBL schemes do a very poor job of it• These are thunderstorm, hurricane, and

frontal models—who cares about a still, stagnant day?

Meteorology: Winds

• Observations • Modified Blackadar• Winds from other

PBL schemes have essentially nothing to do with reality

• Comparisons by NYDEC

Meteorology: Temperature(modified Blackadar)

0 10 20 30 40 50 60 70 80 90285

290

295

300

0 10 20 30 40 50 60 70 80 901

2

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5

070897 12Z - 071297 00Z

Temperature (K)

Wind Speed (m/s)

Data comparisons By NYDEC

Photochemistry

Emissions:• MEPPS with 1995 National Emissions Trends

Inventory• NOT extrapolated to 1997

CMAQ:• 23 vertical levels, 110 x 80 (East-West x North-South)

12 km horizontal resolution• 72 hours of spinup before July 13• CB4 chemical mechanism, MEBI solver

Measurements

THE AIRCRAFT: Instrumented Cessna-172*Chemistry:

• Ozone, Carbon MonoxideMeteorology:

• Relative humidity, Temperature, Pressure altitude

*Currently, we fly a twin-engine Aztec with CO, O3, SO2, PSAP, T, RH, Palt, nephelometer, Met One counter, streaker—B. Doddridge, L. Marufu, B. Taubman

The domain

Measurement sites

W29

W42

GAIHOL

WAY W05

Measurements

• Examine: July 13-14, 1997

• Four measurement flights

• Ozone data only (CO malfunctioned)

• First show everything, then go back

• Used the old MM5 data!

Gaithersburg, MD07/13/97 06:41 - 06:56 EDT

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KEY:CMAQAircraft

Gettysburg, PA07/13/97 07:29 - 07:42 EDT

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Holbrook, Southwestern PA07/13/97 09:50 - 10:01 EDT

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Waynesburg, Southwestern PA07/13/97 13:21 - 13:32 EDT

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Gettysburg, PA07/13/97 14:53 - 15:33 EDT

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Fallston, MD (NE of Baltimore)07/13/97 16:08 - 16:20 EDT

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Bay Bridge Airport Eastern Shore, July 14

7/14/97 11:48 - 12:07 EDT

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Waynesburg, Southwestern PA7/14/97 13:48 - 13:58 EDT, WAY

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Waynesburg, Southwestern PA07/14/97 16:43 - 16:56 EDT, WAY

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Gettysburg, PA07/14/97 17:33 - 17:48 EDT

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Fallston, MD (NE of Baltimore)07/14/97 19:55 - 20:07 EDT

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Measurements

• July 13, Gettysburg PA—structure in both AM and PM flights, but not quite enough ozone.

• July 13, Fallston MD—may be just outside the Baltimore plume.

• July 14, Bay Bridge Airport—obviously, 12 km resolution just isn’t enough to get the Bay Breeze effects right. Our Met modelers suggest that maybe 2 km resolution will do it, probably 1 km resolution.

AM

PM

Future

• Compare CMAQ simulation results for this run and for a run with the new-and-improved MM5 PBL scheme.

• This should help identify the role played by the boundary layer scheme in these simulations.

Acknowledgements

• Da-Lin Zhang & Weizhong Zheng, UMD MM5 modeling

• Bruce Doddridge, Lackson Marufu, Brett Taubman, UMD aircraft measurements

• Gopal Sistla, NYDEC, comparisons between MM5 and measurements

• Fiscal Support: Maryland Department of the Environment