Analysis of OTC Modeling BaseRAMMPP Modeling Team

Review of Application and Assessment of CMAQ in OTRNovember 16, 2005

• Outline

• Scatterplots of model-calculated and aircraft-measured O3

• Flight-by-flight box plots • Summary• Episode Analysis (June 11 and/or August 12): Time permitting

UMd Research AircraftUMd Research AircraftGPS Position (°Lat, °Long)

Meteorology (T, RH, Pr, Palt)

Carbon Monoxide (CO)

Ozone (O3)

Sulfur Dioxide (SO2)

Aerosol Optical Properties:Absorption, Bap (565 nm)

Scattering, Bscat (450,550,700

nm)

Particle Counts (CPC: TSI 3007)

Aerosol Particle Size (MetOne)

6 cuts: range 0.3–1.0μmAerosol Chemistry (PIXE

Streaker)*Aircraft operated by: University Research FoundationUniversity Research Foundation

Summary of aircraft comparisons

• Overall (after removing fire flights), CMAQ-calculated O3 concentrations are ~4% too high below 500 meters and 4-7% too low above 500 meters.

• Model-calculated O3 on August 12th is much too low throughout the sampled column. However, the shape of column is captured . Bias does not vary with altitude.

Acknowledgements

• Met modeling: Da-Lin Zhang, Shunli Zhang• CMAQ modeling: Jeff Stehr, Charles Piety,

Gopal Sistla & NYDEC, and a cast of thousands• Emissions: Sheryl Ehrman and Patti

Castellanos & many others• This research was supported by Maryland

Department of the Environment under the RAMMPP project

Summary of surface layer comparisons

• Extremely good simulation of 1-hr (8-hr) maximum O3. R>0.9.• Good simulation of 24-hr avg PM2.5

• CMAQ-calculated O3 concentrations have high bias at night leading to a 10% high-bias in 24-hr avg O3. Biases in 1-hr and 8-hr maximum O3 are small.

• CMAQ-calculated 1-hr maximum O3 concentrations over MD are 10-15% too low during major pollution events.

• PM2.5 biases are small after removal of July fire event.

• Diurnal variation in O3 well simulated. No obvious (eyeball norm) temporal shift in timing of maxima/minima.

• Spatial pattern of O3 pollution events is well captured by CMAQ. • With a few exceptions, spatial pattern of PM2.5 events is also well captured.

June 11, 2002 Weather and Air Quality

Date Max8hr/

#Monitors ≥ 85 ppbv

Max1hr/

#Monitors ≥ 125 ppbv

Environ

Pattern

Transport

Regime

6/11 117/13 144/3 5 High Ozone Along

the I-95,Corridor

SouthWest/Local

850 mb Geopotential Height (11 June, 2002)

24 Hr Back Trajectory (11 June, 2002)

August 12, 2002 Weather and Air Quality

Date Max8hr/

#Monitors ≥ 85 ppbv

Max1hr/

#Monitors ≥ 125 ppbv

Environ

Pattern

Transport

Regime

8/12 116/15 143/2 3 High Ozone Confined

to the Extreme Southeastern OTR

West

850 mb Geopotential Height (12 August, 2002)

24 Hr Back Trajectory (12 August, 2002)

Model-calculated O3 was saved on the lowest 16 CMAQ layers. Following Kevin Civerolo’s (NYDEC) and Shunli Zhang’s (UMD) method, the centers of these layers were assumed to be:

[10, 24, 68, 116, 185, 282, 398, 544, 727, 949, 1212, 1523, 1886, 2312, 2820, 3393] Meters Above Ground Level (MAGL)

•To convert to meters above sea level, we added in the surface elevation ofeach grid point (HT_SFC). These data are archived as part of MM5 output.

Therefore: MASL = MAGL + HT_SFC

Comments on Derived Variables and Figures in CMAQ/Aircraft Comparison Plots

* This approximation ignores spatial variations in temperature. However, the approximation should be satisfactory during the summer months covered in this aircraft comparison.

How is Meters Above Sea Level (MASL) calculated from model output?

-The curtain plots use pressure as the vertical coordinate.

-The model pressures seen in these plots were calculated assuming a surface pressure of 1013.24 hPa.

-Aircraft pressures were read in from the RAMMPP data sets.

Comments on Derived Variables and Figures in CMAQ/Aircraft Comparison Plots

How are pressures estimated for model output?

*A more accurate specification of surface pressure is desirable. In the interim, future MDE curtain plots may use MASL as the vertical coordinate.

1. The longitude, latitude, pressure-altitude, and time of individual aircaft samples are read in from RAMMPP data sets. (RAMMPP data sets that do not include longitude, and latitude are not included in these plots.)

2. MASL is calculated for gridded output.

3. The aircraft in then “flown” through the model domain (x,y,z,t). -For each aircraft sample, we determine the model grid box that is closest in longitude (x), latitude (y), and sample time (t).

For these values of x, y, and t, we then interpolate linearly in height in the vertical (z) to obtain our value.

Comments on Derived Variables and Figures in CMAQ/Aircraft Comparison Plots

How is model output extracted at the location of aircraft measurements?

1. Model output is extracted at the location of aircraft measurements.

2. For each flight, model output and aircraft measurements are sorted by pressure. 3. Successive, XX-pt moving averages are applied to the model output, the aircraft measurements, and the sampling pressures until averaged values are obtained for the entire profile. These values are then plotted.

Comments on Derived Variables and Figures in CMAQ/Aircraft Comparison Plots

What is a "XX-pt data smoother?"

1. Model output is extracted at the location of aircraft measurements.

2. Model output and aircraft measurements are binned into 1/4 km bins using MASL.

Comments on Derived Variables and Figures in CMAQ/Aircraft Comparison Plots

How are the "leaning tower" box plots created?

-The measured-mean is shown by an asterisk.

-The mean plus and minus a standard deviation is shown by the boxes.

-The solid line shows the mean of the model.

-The thinner lines show the model-mean plus and minus one standard deviation.

Which flights are flagged as "fire" flights?

Flights 24 and 25 on July 8th were flagged as "fire" flights.

Comments on Derived Variables and Figures in CMAQ/Aircraft Comparison Plots

Which flights did not include longitude/latitude data?

Flights 4 and 31. Output from these RAMMPP flights were not included in thisanalysis.