Snow Rules!

Enhanced Snow and Precipitation Monitoring within Minnesota Portions of Watersheds Draining to Lake Superior

Minnesota’s Lake Superior Coastal Program

Water temperature monitoring using Thermochrons

The Snow Rules! project uses DS1921Z thermochron iButtons to log temperatures in shallow water. Deployment depths range from 0.4 to 2.0m. Some have been in place for over a year. Some special issues have arisen for these sites. The 'near Sugarloaf' device, last read in late April 2004, was buried shortly thereafter by storm waves which deposted a new gravel bar over the observation location (i.e. the device is presently under more than 2 feet of gravel). The Stewart River device which is mounted on a board and weighted to the stream bottom with large rocks was temporarily lost when a 3 inch rain produced a flood in that stream that washed the device downstream. That device was later found and restored to its original observing site. It looks the worse for wear but it is still working.

Each mounting is designed for the specific application. The Wolflake device is suspended between an anchor and a float while the Bear Lake device simply hangs from a cord at the end of a dock. Where waves, storms, or flowing water are involved more robust methods are needed. The Stewart River device is (as mentioned above) mounted on a board and then weighted with heavy rocks - but even that is obviously not enough at times! The Sugar Loaf device was wired to a heavy cast iron piece of dock hardware.

Data from five sites are currently available:

The 'Sugar Loaf' anchor system holds the thermochron inside a space desiged to fit around a dock pipe. For deployment, the thermochron in its blue clip is pulled inside the pvc pieces. The pvc sleeve is then bolted inside the dock part. The dock part prevents large cobbles from striking the device directly. The 'flattish' overall shape and great density (cast iron) make it more difficult for a large wave to pick up and toss the assembly. The siting also took advantage of a large emergent rock (mini-island) just offshore. The device has stayed where it was put but a flood of a nearby creek together with large waves piled 2 or more feet of fine gravel on top of the device. The next reading awaits another storm that removes the gravel bar.
The Stewart River experienced a flash flood following 3 inches of rain at the end of May 2004. The thermochron was tumbled down river in a heap of stoney debris. A dent and scatches can be seen on the case of the device. It still works fine!


Snow Rules! main page
State Climatology Office, DNR - Waters, 2004
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