IWA Publishing

Reflecting on the status of precipitation data collection in Alaska: a case study

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Measuring precipitation, especially solid, at high latitudes is a challenge. In Alaska (USA), the extreme topography, large regional extent, and varying climate result in annual precipitation values ranging from 120 in. (3,050 mm) to 10 in. (254 mm). The state's precipitation network recently has expanded significantly, but there is still room for improvement. A recent intensity-duration-frequency (idf) exercise for the state showed that: (1) although density and spatial coverage of stations have increased, large areas in northern and western Alaska are still without gauge coverage; (2) the number of gauges at higher elevations is insufficient, although growing (e.g., the number of stations above 1,000 ft (305 m) increased from 26 gauges in 1963 to 134 gauges in 2012); (3) solid precipitation is difficult to quantify, and at unmanned sites, the phase of precipitation (liquid or solid) is hard to determine, as air temperature is often the only other measured variable; (4) corrections for gauge undercatch need to be made but too often information on the shielded status of gauges and wind speed is lacking; and (5) in the recent idf analysis only about one-third of the existing and historical stations were used because of data-quality issues. Obviously, overall improvements in precipitation data collection can and should be made.

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