Remote Sensing of Ice Cover (Adapted from a presentation at UCOWR: Snowbird, Utah; June 2019)
Ice cover and ice-free periods impact aquatic habitats and have an important role in ecological processes and surface-atmospheric interactions. It can also serve as a useful indicator of local changes in climate, reflecting changing patterns in seasonal air temperature. Utah Lake currently lacks a consistent record of ice cover characteristics, making it difficult to evaluate trends or patterns or how ice cover relates to seasonal climate conditions. The relationship between climate (especially air temperature) and ice cover is especially important for shallow lakes like Utah Lake.
Using historical imagery from multiple satellites, we can construct a record of ice cover characteristics for Utah Lake and use this record to evaluate important characteristics such as timing of ice-on/off, duration, and spatial extent of ice cover.
This type of information is helpful for validating hydrodynamic models that simulate ice conditions. For example, an EFDC model built to support Utah Lake water quality modeling simulates surface water temperature. The remote sensing record from Landsat imagery shows that ice cover extends beyond the periods of potentially suitable conditions (surface temperatures < 0 degrees) simulated by the model.
With the historical record, we are able to compare the observed patterns to trends found in other regions in the northern hemisphere over the same time period. One notable example of lake ice-cover analysis is Lake Mendota and the dataviz challenge hosted by r/dataisbeautiful. Long-term records of this lake indicate later freeze-up, earlier break-up, and shorter durations over the last 160+ years.
Summary of Lake Mendota ice cover visualization challenge
Imagery of Utah Lake suggests that ice cover can be highly variable. Earliest dates of observed ice (from 1988-2019) are December 10 (2014) and latest observed ice occurred on March 13 (2004).
We can also compare ice cover trends to several atmospheric variables measured by meteorological stations and remote sensing to explore how trends in ice cover compare to local climate trends.
Locally, there has been a decrease in winter precipitation in the valley and snow water equivalent (SWE) in the mountains. Temperatures throughout the year have generally increased over the last several decades, and wind speed has generally decreased (though it has not been reported during the winter).