Lake Ice and 
Snow Science 

LAKE ICE: Variability

Between the beginning of freeze-up and the beginning of break-up the lake ice thickness increases primarily by thermodynamic processes (freezing of water) which can be understood relatively easily in terms of heat conduction driven by the energy balance at the top surface. On larger lakes dynamic processes (deformation of the ice due to motion) may come into play.

The thermodynamic processes are dependent on snow (depth and density) and air temperature. Since these vary from place-to-place (spatial) and year-to-year (temporal), it is not surprising that lake ice thickness (and composition) varies too.

LOCAL VARIATION IN SNOW DEPTH AND
ICE THICKNESS AT PFRR (2004-2005)

The distance between MST Pond and 33.5 Mile Pond is 2.5 miles. Maximum ice thickness was 0.68m at MST Pond, 0.71m at 31.6 Mile Pond and 0.69m at 33.5 Mile Pond.

QUESTIONS: What could account for the differences in the PFRR 2004-2005 data? Are they significant?

Snow depths and ice thicknesses vary more dramatically over larger areas due to differing climatology:

• Arctic Coast: Winters are long and have low wind chills, low precipitation and frequent blowing snow (Barrow).


• Bering Strait Coast: Warmer (longer) summers than Arctic coast. Moderately windy with capes and passes very windy (Nome).


• Interior: Coldest zone in winter with light winds (Amos Lakes and Fairbanks).


• Southcentral: Transition between Interior and Pacific Coast (Wasilla).


• Pacific Coast: Rain and snow in winter with moderate to strong winds (Seward).

QUESTION: Why is the wind an important factor in lake ice thickness?

Click here to see the temporal variability of PFRR pond ice.