Site Name

IMPROVE: SPOK1

Region

Columbia Plateau

Terrain

Terrain is shown in the 2 km terrain map and the 20 km terrain map.

The Spokane Indian Reservation is located in northeastern Washington, 100 km (60 mi) northwest of the city of Spokane. It is bordered on the south by the Spokane River and on the west by the Columbia River. The mouth of the Spokane River at its junction with the Columbia River is at the westernmost Reservation boundary. Terrain is mountaints and eroded Plateau. Elevation at Columbia River level is ~ 400 m. Highest ridge crest elevations are near 1,000 m. The elevation of Spokane Mountain in the western area of the Reservation is 1,180 m.

The SPOK1 IMPROVE site is a tribal site, elevation 548 m (1,797 ft) near the center of a wide (7 km) flat valley bottom, Chamokane Creek, near the eastern Reservation boundary. Surrounding terrain rises to 700 to 750 m on the west ridge, 750 to 800 m on the east ridge.

Representativeness

The SPOK1 IMPROVE site should be representative of the Spokane Reservation. There may times when it is within a wintertime surface based valley inversion in the Chamokane Creek valley.

Nearby Population/Industrial Centers

Spokane Washington is 40 km (25 mi) southeast of SPOK1. Columbia Plateau sources including agricultural and crustal (dust) components may impact the site. Highest aerosol concentrations may result during summertime western wildland fire episodes.

Nearby Meteorological Network Monitoring Sites

Nearby meteorological monitoring network stations with respect to the SPOK1 IMPROVE site are shown in the data network map and at the RAWS station US Climate Archive site. The Midnite 2 Washington RAWS and the Wellpinit Washington RAWS site are both close to SPOK1 and hourly data from these sites should be representative of concurrent meteorological conditions at SPOK1. Longer term data are available from the Spokane/Felts Field SAO.

The most representative upper air site is also at Spokane Washington (OTX). This and other upper air sites are accessible via the University of Wyoming Dept of Atmospheric Science web page.

Wind Patterns

Synoptic winds in the region are generally westerly, with more northwesterly flow during the summer when the Pacific High is off the coast of northwestern U.S., and more westerly flow during the winter when the Pacific High has retreated southward. Monthly Spokane Washington wind roses indicate this pattern, although wintertime wind directions are more northeasterly, bringing continental air southward with high pressure over the Canadian interior. Note that these surface wind patterns may differ somewhat from upper level winds because of terrain effects. During the winter, with high pressure over the Great Basin and Idaho and low pressure west of the Cascades easterly gradient (synoptic) flow is common.

Inversions/Trapping

The SPOK1 site is at a wide valley bottom location and may at times be within a surface based trapping inversion, especially in the wintertime. On a larger scale, persistent low-level temperature inversions over the Columbia Basin may also keep pollutants trapped at low elevations during most of the winter. Mixing heights calculated for Spokane Washington (Ferguson and Rorig, 2003), show winter heights generally below 300 m (1,000 ft). Spring and summer Spokane mixing heights frequently reach to 1,500 m (4,920 ft). Calculated Fall Spokane mixing heights were typically near 900 m. Regionally, summertime subsidence inversions associated with the establishment of the semi-permanent Pacific high-pressure system could result in regional aerosol buildup over periods of days. Subsidence inversion heights are typically at elevations of 2,000 to 3,000 m (6,000 to 10,000 ft). Highest regional aerosol concentrations may occur during summertime stagnation and subsidence inversion periods in conjunction with western wildland fires.

Climatological Statistics

Spokane Washington Normals Means and Extremes are representative of low elevation locations in the central Columbia Plateau. Other Washington Climate Summaries are available from the Western Regional Climate Center.

Meteorological Indicators

(to be completed)

Keywords