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Meteorological Station Information, Gulkana Glacier, Alaska

Introduction

This web site presents air temperature and precipitation-catch measurements recorded at Gulkana Glacier basin from 1968 through 1996 hydrologic years (October 1 through September 30), as part of a long-term glacier-monitoring program. The air temperature data set is 96 percent complete. The precipitation data set is 83 percent complete; precipitation data for 1993-96 are missing. The data set is important because it provides long-term climate information from the highest year-round climatological recording site in Alaska. Gulkana Glacier is a compound valley glacier fed from several cirques on the south flank of the eastern Alaska Range. The glacier is one of three long-term glacier-monitoring sites operated by the U.S. Geological Survey. The other glacier-monitoring sites are Wolverine Glacier in south-central Alaska and South Cascade Glacier in Washington. Climate, glacier-motion, mass balance, and stream-runoff data are recorded at these three sites to develop a better understanding of glacier-related hydrologic processes.

Instrument Site and Climate Description

The Gulkana climate station (lat 63°16' N., long 145°25' W.) is located at an altitude of 1,480 meters (m) on the crest of a wind-swept, ice-cored moraine along the eastern boundary of the glacier. The station is slightly lower than the glacier's average equilibrium line altitude (ELA) and approximately 300 m from the east edge of the glacier. The average ELA is near 1,735 m which is consistent with a continental mountain climate. The average annual air temperature at the recorder site is about -4 degrees Celsius(°C), and the average annual precipitation-gage catch is about 1,000 millimeters (mm). Snowfall is the dominant form of precipitation and usually accumulates on the glacier from September through mid-June. Daily average temperatures range from a low of -35°C to a high of 16°C. Daily precipitation catch ranges from a low of zero to a high of approximately 100 mm.

Data Collection and Equipment

Weather station equipment consists of an air temperature sensor in a vented shelter, a precipitation gage with a windshield and steel storage tank, and an analog strip-chart recorder mounted inside a shelter on the storage tank. The meteorological equipment has remained essentially the same since the station began operation in 1967. Installation and testing of digital climate-recording equipment designed for satellite data telemetry began in September of 1995 and is in progress.

Data Accuracy

The daily average temperatures have an accuracy of about ±1.0°C (Mayo and others, 1992; Kennedy, 1995). The daily precipitation catch has an estimated accuracy of about ±0.005 m (Kennedy, 1995). Individual year gage-catch efficiencies show a large variability, ranging from 0.2 to 1.0 (Rod March, USGS, oral commun., 1996). Despite the uncertain catch efficiency, the recorded precipitation-gage catch is a useful indicator of when and relatively how much precipitation occurs in the basin.

References Cited

Kennedy, B.W., 1995, Air temperature and precipitation data, Wolverine Glacier Basin, Alaska, 1967-94: U.S. Geological Survey Open-File Report 95-444, 79 p. and diskette.

Kennedy, B.W., Mayo, L.R., Trabant, D.C., and March, R.S., 1997, Air temperature and precipitation data, Gulkana Glacier, Alaska: U.S. Open-File Report 97-358, 144 p. [Abstract]

Mayo, L.R., March, R.S., and Trabant, D.C., 1992, Air temperature and precipitation data, 1967-88, Wolverine Glacier basin, Alaska: U.S. Open-File Report 91-246, 80 p.

Connections

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