Site Name

IMPROVE: FOPE1 (Fort Peck)

Region

Northern Great Plains

Terrain

The Fort Peck Reservation is in northeastern Montana, 40 miles west of the North Dakota border, and 50 miles south of the Canadian border, with the Missouri River defining its southern perimeter. It includes more than two million acres of land.

The Fort Peck Reservation Area IMPROVE site FOPE1 is located on flat land 400 m west of Poplar River and 23 km north of the Missouri River. Site elevation is ~ 638 m (2093 ft). The surrounding terrain is flat. The site thus has good exposure to regional scale transport winds. Surrounding terrain is predominantly agricultural land and moderate grassland. Terrain in the area is depicted in detailed 20 km terrain map and 2 km terrain map.

Representativeness

Aerosol data collected at the IMPROVE site should be very representative of visibility conditions within and surrounding Fort Peck Reservation.

Nearby Data Stations

This map shows the location of the nearest air quality and meteorological monitoring sites, with respect to the FOPE1 IMPROVE site. Meteorology is not presently monitored at the site. The nearest CASTNET site, with meteorological monitoring, is THR422 at Theodore Roosevelt National Park, located 205 km south-east of the Fort Peck Reservation. Historical meteorological data from THR422 site probably provides good representation of meteorological patterns at the Fort Peck Reservation.

The nearest upper air site is Glasgow RAOB site, which conducts atmospheric soundings twice daily, located 113 km west-southwest of the monitoring station. Vertical atmospheric data from Glasgow should be the best available representation of vertical atmospheric structure at Fort Peck Reservation Area.

Wind Patterns

The FOPE1 IMPROVE monitoring site is well exposed to prevailing synoptic wind patterns due to the relatively flat topography of the region. Winter is characterized by frequent outbreaks of cold continental air from the Canadian interior. A severe type of snowstorm that frequently occurs during this synoptic condition is referred to as the Alberta Clipper. During the rest of the year the migration of the jet stream to more northerly latitudes results in more frequent transport of warmer moist air from the Gulf of Mexico and warm dry air from the southwestern U.S.

Long term (1961-2002) Glasgow Montana wind roses are representative of regional wind patterns. Wind directions in the area are a consequence of the synoptic pattern and are predominantly southeasterly and northwesterly in the winter. During the rest of the year there is a higher frequency of northwesterly to southwesterly flow. The Poplar Montana annual wind rose from the Poplar Montana RAWS site, near the Fort Peck Reservation, shows strong westerly to easterly flow, with some flow from all directions. Note that this data is from July 1, 1992.

Inversions/Trapping

Because of the flat terrain in the region, inversions in the Fort Peck Reservation Area probably are not trapping inversions, but rather subsidence inversions associated with buildup and stagnation of synoptic high pressure ridges. They tend to cover a large area and are regional in nature. They may persist for periods of days until ventilation occurs in conjunction with frontal passages or onset of stormy low pressure systems.

Climatological Statistics

Climatological data available from the CASTNET site, THR422, should be very similar to Fort Peck Reservation as the two sites are located in similar terrain and land cover and are separated by ~205 km. Longer term Bismarck North Dakota Climate data is also regionally representative

Meteorological Indicators


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