April 9,1997



In light of the extensive presentations from stakeholders planned for the April OTAG Policy Group meeting, the Air Quality Analysis workgroup will not be presenting its monthly update to the Group (I know, heavy sigh!).


Instead, we will be focussing our efforts on preparing a knock-your-socks-off presentation for the May meeting. This presentation will re-cap and summarize the most salient results from the myriad analyses emanating from our workgroup. A brief outline of that presentation is shown on the next page. If you do not see your favorite air quality analysis issue appearing in that outline, please let Dave Guinnup or one of our workgroup members know ASAP so we can correct the oversight!


Further, our workgroup wanted to take this literary opportunity to remind the Policy Group membership that a draft version of our workgroup’s report is currently available on the Air Quality Analysis workgroup’s Internet website at


in three volumes. The three volumes are:






Please feel immediately compelled to browse our website and leave your comments on any part of our draft report. This is especially desired for our Executive Summary, which is intended to be directly relevant to the policy questions facing the OTAG Policy Group. With your feedback, we can make every effort to see that it truly is policy relevant.


Comments are also needed on the detailed technical reports which underly and support the Summary. This is especially important for a number of recently-submitted reports, for which shrinking time

and resources may not allow a full internal review.


Finally, on the last page of this handout is a list of technical papers on our website which in some fashion address analyses of model performance related to air quality data and the implications of those analyses toward interpreting model results, such as those recently arising from the Round 3 runs. Please feel free to browse these papers to assist you in interpreting the multiple results from the plethora of model runs facing the Policy Group. And good luck!.......

Outline of AQA Workgroup Presentation

to Policy Group, May, 1997


  1. Climatological Ozone Patterns in and around the OTAG Domain
  2. Ozone Precursor Emission Patterns in OTAG Domain
  3. Exceedance/violation Patterns in OTAG Domain (Current/Proposed standards)
  4. Transport Patterns across OTAG Domain
  5. Airmass Trajectories on High and Low Ozone Days
  6. Typical Transport Distances resulting from Statistical and Pattern Analyses
  7. Control Implications from Air Quality Analyses
  8. Comparisons of Air Quality Data to Model Predictions during OTAG Episodes

  1. Using the Weight-of-Evidence Approach to Understand the Ozone Problem
  2. Recommendations for Continuing the OTAG "Process"


AQA Reports on the Website Related to Model Evaluation

April 9,1997


Summary: Transport, Mixing Phenomena and Model Performance over the Northeast. Two complementary assessments were performed and are summarized: (1) Transport and mixing phenomena related to ozone using data from 1995 NARSTO-NE. (2) Results of the OTAG modeling for the northeast U.S. were evaluated using air quality and meteorological data from NARSTO-NE and other data. Submitted by Donald L. Blumenthal on 4/1/97


EVALUATION OF THE UAM-V MODEL PERFORMANCE IN THE NORTHEAST REGION FOR OTAG EPISODES. This draft report is the second part of an assessment of regional transport issues in the Northeast and how well the transport and its effects are represented by models applied to the area. Submitted by Frederick W. Lurmann on 3/31/97.


Comparison of Modeled versus Observed Isoprene Concentrations. UAM-V model output for the 1995 OTAG episode was compared with field observations from 16 rural and suburban sites operated by N-NE,SOS/Nashville and PAMS. Afternoon values were compared in order to eliminate, or at least minimize, vertical gradients and transitory excursions in isoprene concentration. Submitted by Eric S. Edgerton on 3/18/97.


PHASE I COMPARISON OF OTAG UAM-V/BEIS2 MODELING RESULTS WITH AMBIENT ISOPRENE AND OTHER RELATED SPECIES CONCENTRATIONS. Readily available ambient air quality data to compare observed isoprene concentrations with concentrations predicted by the UAM-V photochemical model simulations for the July 10-18, 1995 episode. Submitted by Marcel Haberstadt on 3/18/97.


TRANSPORT AND MIXING PHENOMENA RELATED TO OZONE.. This working draft is based on analyses of NARSTO-NE data. Submitted by Donald L. Blumenthal on 3/11/97.


Quality of Explanation: Thinking about and using air quality models. Slides from the presentation at the February 26 OTAG meeting. Submitted by Harvey Jeffries on 2/25/97.


Analysis of Ozone, NOy and Tracer Data from a Site in South-Central Pennsylvania. This report examines the behavior of O3, CO, SO2 and NOy at a rural site in south-central Pennsylvania. Periods of elevated O3 are classified based on the abundance of CO and SO2 relative to NOy. Results indicate that of the 21 periods of elevated O3 in the summer of 1995, 7 were classified as "predominantly urban", while the remaining 14 were classified as "mixed". Submitted by Eric S. Edgerton on 1/6/97.


A Comparison of Modeled and Measured Ozone, NOy and CO at Nine Regional Monitoring Stations. The comparison of measured an model showed reasonable agreement for the mean ozone concentrations and in the ozone-NOy relationship while NOy and CO concentrations did not agree as well. Under conditions where the model predicted the highest ozone concentrations, model predictions of all three species showed a significant positive bias. Submitted by Ben Hartsell on 11/24/96.


Source Regions of Influence for High and Low Ozone Conditions in the Eastern US. Characteristic transport wind speeds and directions show that low ozone concentrations are typically associated with strong transport of clean air from outside of the OTAG domain, while high ozone levels coincided with low wind speeds except in New England where high ozone was associated with strong westerly winds. Submitted by Bret A. Schichtel on 8/26/96.


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