Comments on UAM-V model use to evaluate control options

Model/Data Comparison

Bullet #2: The north/south bias varies from episode to episode, but can be very substantial. The word "some" understates regional
differences in model performance.



Bullet #4: Precursor emissions generally show marginal to poor agreement, especially for isoprene. In addition, comparison of model and
observed CO (a tracer of automotive emissions) also shows poor agreement for the 1995 episode (8-10 rural and suburban sites).



Bullet #5: O3/NOx should be O3/NOy. Although this is encouraging behavior, it should be noted that agreement was much poorer for
O3/NOx in urban and suburban locations (VOC limited?). These results neither add nor detract from use of the model to evaluate control
strategies (there's no alternative); they do provide a context for interpretation of model results.

Submitted by Eric Edgerton on 4/14/97 RecID: EricEdgerton

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Volume I: Executive Summary--UAM-V model use

Second sentence: The order of "overpredict" and "underpredict" is reversed.

Fifth and sixth sentences should read "...while limited by the availability of measurements, shows somewhat poorer, but not unreasonable, agreement. Comparison..."

Submitted by Mike Koerber on 2/24/97 RecID: MikeKoerber

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4 episodes vs all episodes

One area where the climatological AQA analyses can both help validate, and provide important supplemental information to the model results is on the "meteorologically-dependent" aspects of model results. I don't think either we (AQA) or the modelers (who caution only the need to look at more than one episode) have clearly articulated that there are aspects of the model results (from any one or all 4 model episodes) which are dependent on the unique meteorological conditions at the time of the model episodes, and which should not be taken as representative or predictive of future conditions. For example, an individual episode may provide little insight into the typical duration of local stagnation/accumulation in individual source regions, or the distance, direction or persistence of subsequent transport which typically characterize episodes in general - in specific subregions or in OTAG as a whole. Any specific episode is likely to have flows over any location which are relatively uni-directional by comparison to the flows from that region over a larger number of episodes. Consequently, a model-only interpretation that controls in region A may reduce concentrations in region B, may be supplemented by AQA to indicate that controls in A may help regions B, C and D (or conversely that the benefits in region B from controls in A appear to represent a relatively rare event).

Submitted by Richard Poirot on 2/22/97 RecID: RichardPoirot1

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Volume I: Executive Summary--UAM-V model use

Sentence 1, insert after large-scale regional and insert after future regional. Sentence 4, insert after is that nighttime.

However, due to these limitations, modeling results should not be interpreted as definitive but rather as one part of the analysis.


Submitted by Jeffrey West on 2/18/97 RecID: JeffreyWest

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Under or Over?

Is this not backwards: "There appear to be sometendencies for the model to over predict daily maximum ozone levels in the northern portion of the
domain and under predict the same for the southern portion of the domain." I thought the overpredictions were generally in the SW and underpredictions in the NE?

Submitted by Richard Poirot on 2/13/97 RecID: RichardPoirot

Re: Under or Over?

You're right Rich. thanks


Submitted by David Guinnup on 2/14/97 RecID: DavidGuinnup

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