I am interested in the formation and decay of ice, particularly frazil and anchor ice, and in the interactions between ice and sediment.  I am also interested in sediment transport by ice (ice rafting), and the effects of ice on river flow and river morphology.

One of the tools I use to study anchor ice is an underwater video system.  The `Anchor Ice: A Video Tour' page contains a number of short video clips that illustrate anchor ice/sediment interactions.  All of the river videos in the tour were collected in the Laramie River in Wyoming and the Cache la Poudre River in Colorado during the 2003-2005 winter seasons.  

 

FRAZIL ICE FORMATION, ANCHOR ICE FORMATION, AND ICE RAFTING    Not all ice forms on the water surface. In turbulent flows like streams the water column can supercool (i.e. the water temperature is cooled to below the freezing point). When this happens, ice can grow in the water column. The first ice to appear is frazil (small disks or spicules of ice suspended in the water column). When turbulence transports frazil to the river bed, the frazil may stick to the bed, forming anchor ice (ice attached or anchored to the bed).

Anchor ice mass collected from the bed of Lake Michigan, near Chicago, Illinois. The ice mass is formed from delicate, interlaced ice crystals. This piece of anchor ice is about 40 cm in diameter.

The formation of frazil and anchor ice depends on meteorological conditions. In 1982, Gee Tsang* outlined the conditions for frazil and anchor ice formation in simple terms: In common language, one says that frazil an anchor ice are likely to form on a cold, clear night when the wind is strong, the humidity of the air is low, and the river is at minimum flow, especially if such a night follows a cold, windy, cloudy day.   As Tsang says, in mid-latitudes anchor ice tends to form at night. On mornings following anchor ice formation events, the sun warms the water, and anchor ice is released from the bed. This anchor ice floats downstream, where it either melts or is incorporated into the growing surface ice cover. The best time to view anchor ice in the United States is on a cold, clear morning in November. Because it forms at night and is released from the streambed in the morning, and it is very hard to see on the bottom, it is tempting to think of anchor ice as a rarity. However, any river that freezes at any time during the winter has the potential of forming frazil and anchor ice. Anchor ice is not restricted to rivers. It can also form in shallow water in lakes and oceans when the water column is agitated by waves.    * Gee Tsang, 1982, Frazil and Achor Ice: A monograph, NRC subcommittee on Hydraulics of Ice Covered Rivers, Ottawa, Ontario, Canada, p. 93.

Released anchor ice masses floating down the Laramie River. Flow is towards the bottom of the page. The open-water channel in the river is about 10 m wide.