Analysis of OTC Modeling Base

1. Analysis of OTC Modeling Base RAMMPP Modeling Team Review of Application and Assessment of CMAQ in OTR November 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

2. GPS 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 0.3–1.0μm Aerosol Chemistry(PIXE Streaker) UMd Research Aircraft *Aircraft operated by: University Research Foundation

20. 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.

21. 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

22. 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.

23. June 11, 2002 Weather and Air Quality 850 mb Geopotential Height (11 June, 2002) 24 Hr Back Trajectory (11 June, 2002)

29. August 12, 2002 Weather and Air Quality 850 mb Geopotential Height (12 August, 2002) 24 Hr Back Trajectory (12 August, 2002)

35. Comments on Derived Variables and Figures in CMAQ/Aircraft Comparison Plots How is Meters Above Sea Level (MASL) calculated from model output? • 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 of • each grid point (HT_SFC). These data are archived as part of MM5 output. • Therefore: MASL = MAGL + HT_SFC * This approximation ignores spatial variations in temperature. However, the approximation should be satisfactory during the summer months covered in this aircraft comparison.

36. Comments on Derived Variables and Figures in CMAQ/Aircraft Comparison Plots How are pressures estimated for 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. *A more accurate specification of surface pressure is desirable. In the interim, future MDE curtain plots may use MASL as the vertical coordinate.

37. Comments on Derived Variables and Figures in CMAQ/Aircraft Comparison Plots How is model output extracted at the location of aircraft measurements? 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.

38. Comments on Derived Variables and Figures in CMAQ/Aircraft Comparison Plots What is a "XX-pt data smoother?" • 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.

39. Comments on Derived Variables and Figures in CMAQ/Aircraft Comparison Plots How are the "leaning tower" box plots created? • 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. -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.

40. Comments on Derived Variables and Figures in CMAQ/Aircraft Comparison Plots Which flights are flagged as "fire" flights? Flights 24 and 25 on July 8th were flagged as "fire" flights. Which flights did not include longitude/latitude data? Flights 4 and 31. Output from these RAMMPP flights were not included in this analysis.