Winds Give Assist to Dusting of River Ice
Landsat surveillance by the University's Landsat Quick-Look Program of the Yukon River this spring reveals unusual "dusting" of the river ice at certain wind-prone locations along the river. A pattern of persistent, gusting winds during March of this year has deposited unusual amounts of sand onto the ice from exposed banks and sandbars. Regions of ice which have been wind-dusted are likely to undergo localized melting earlier than the neighboring non-dusted ice. The gray areas on the accompanying maps depict regions of heavy dusting of the ice. Regions with especially significant dusting include Tanana, downstream from Ruby.and Holy Cross, and near Marshall.
Unfortunately, not all the regions prone to ice jams were dusted by winds this spring. One particularly troublesome bottleneck is located downstream from Galena at Bishop Rock on the Yukon River. No winddeposited dust could be detected at Bishop Rock, so only this week's dusting with sand from an aircraft will influence the melting of ice at Bishop Rock. Other river sites artificially dusted as preventive measures, according to the Alaska Division of Emergency Services, includes the Tanana River at the mouth of the Chena River, near Kaltag, Koyokuk, and Holy Cross on the Yukon, and Aniak on the Kuskokwim River.
The localized rotting of the ice in place prior to breakup could mitigate against ice jams when the main body of ice breaks up. There are many other factors that influence the timing and severity of breakup besides natural and man-made dust placed upon the ice, but the quantity of wind- deposited dust on the river ice this spring should cause earlier than usual melting of ice in those areas that are heavily dusted. Although new snow falling on top of the dust will hide the dust from our eyesight, the dust particles are still present to absorb heat from the sun and thus drastically speed up the process of melting.
What effect will all this dusting of the river have upon the breakup of the Tanana River at Nenana? Probably none. The satellite data show no wind- dusted river ice near Nenana, and artificially-placed sand on the river in that vicinity would surely generate wrath from city officials there. Alaska's great guessing game appears exempt from an impact from this year's windy spell.
