Ambient Monitoring Sites For OTAG (time series) Model Evaluation

Prepared Rich Poirot, VT DEC, January 11, 1996

To: S.T. Rao, NY DEC - Northeast Modeling and Analysis Center (NEMAC), R. Husar, CAPITA

Recent OTAG-related discussions, indicated the need to recommend monitoring sites in the Northeast (approximately the OTR region) which might be used for evaluation of model performance for the (7/88, 7/91, 7/93 and 7/95) OTAG model runs. Ideally, these sites might meet the following objectives:

1 Each site spatially representative of approximately 12 x 12 km model grid squares,

2. Data available for all OTAG model episodes,

3. Hourly data for ozone, NOx and speciated hydrocarbons & carbonyls,

4. Good spatial coverage of model domain (presumably the OTR region?)

These objectives conflict with each other. For example, many ozone sites are generally consistent with objectives 1 & 4. However, there are almost no current or historical NOx data which I would consider representative of 12 x 12 km areas. Pams data will generally meet objective 3, but include a mix of 1 hour and 3 hour data, some with and some without carbonyls. The most detailed PAMS measurements (at Type 2 - maximum emission density sites) are probably not consistent with objective 1, and the northeastern PAMS network (aligned along NE corridor) does not provide regional coverage (objective 4). There are no PAMS data (which includes ozone, NOx and VOCs) available for 88 or 91, and only a few sites for 93. 1995 PAMS data are not yet available for most sites, but 95 PAMS and NARSTO-NE data (which includes more regionally representative sites further West in OTR) will probably be available sometime in February.

Given these conflicting objectives, I have suggested a group of 21 ozone sites in the OTR which approximately meet objectives 1, 2 and 4. At least 7 of these sites also have some NOx data for at least some of the model episodes. I=ve also included a list (incomplete) of PAMS sites, a few of which have some data for the 1993 episode, and most of which should have some data available in a month or so for the 1995 episode. There should also be some 1995 NARSTO-NE data available from other sites by mid-late February. Steve Wofsy and Bill Munger are sending me their detailed Harvard Forest, MA data for the 1995 episode (an excellent rural research site near Ware, MA with ozone, VOC and NOx/NOy). Possibly there will also be some 95 and earlier VOC and NOx/NOy from Whiteface Mtn. (Ken Demerjian), and Wye River, MD and Shenandoah NP, VA (Bill Ryan/Bruce Doddridge).

If this list is too long, I suggest giving priority to: sites above 500 meters; sites with NOx; and rural PAMS sites. Several of the better ozone sites are from the NDDN network, a few of which are also 95 NARSTO-NE sites (VOC, NOx/NOy). Possibly (pending EPA contractor budget games) there may be some difficulty obtaining the most recent data from these sites, but the sites are so good and probability of limited data availability is low.

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