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Author Topic: NW Ontario Lake Freeze-up Using MODIS Satellite Imagery  (Read 3505 times)

Offline HOOP

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NW Ontario Lake Freeze-up Using MODIS Satellite Imagery
« on: December 17, 2007, 12:03:19 am »
This is a look at part of Northwestern Ontario's chronology of lake ice freeze up from December 8-16, 2007, using MODIS satellite imagery.  I posted this as a methodolgy piece which you might find useful for other  jurisdictions.

You can use some freely available satellite imagery to monitor, in a coarse way,  the formation of lake ice and arrival of snow in some parts of southern Canada, and all over the US.  (Unfortunately northern Canada is not covered).   It’s called MODIS Rapid Response System, Real Time Subsets.    They post daily images from two satellites called Aqua and Terra.

Here is the first link:
You should see a keymap like this:

As you can see much of Canada is not covered, but a fair chunk along the south is.

Find the keymap and click in your area.   

You will see 3 images per satellite appear for today’s image.  I prefer the real colour for resolution of open water.    Often the image is covered in cloud, so you have to wait for a cloud free day for your area. 
The date will be at the top.  You can click “prev” to go backwards through the calendar to find a cloud free day.   

If you find a cloud free image in the real colour, click it.  It will appear in 2km resolution.   To increase the rez, click on 1km or 250m.  With the 250m you can see individual lakes.  Below are some examples from Northwestern Ontario around the Thunder Bay area, where I know some of the lakes.  I am going to go backwards in time to get an idea of the freeze up chronology and patterns.

This is the lowest rez image from the Terra satellite for the Thunder Bay area of Northwestern Ontario, on Dec.16, 2007.  This is as far north as the coverage goes in Ontario.  The Midwest States are obscured in cloud.  I will now zoom in and look at some lakes.

Same image, Dec 16, zoomed close to Thunder Bay, with Lake Nipigon at the northeast and Lake Superior at the bottom.  Lake Nipigon’s north end is covered in new ice, and the south of the lake is open.  You can see many lakes covered in white, which is snow covered ice.   I zoomed into the entire zone and saw that almost all the lakes north of the border appeared to be covered in ice.   That’s great, but how long have they been covered?   Go back in time to previous images to see when they were open.

Dec 14, zoomed in east of Lake Nipigon.   Long Lake shown in the black arrow, is only half covered in ice.  It’s a huge, very deep lake, so it takes along time to freeze, and its manipulated by Hydro.  Dog Lake, just north of Thunder Bay shown in the red arrow, is also partially open in the south end.  Its big and deep, and also manipulated for Hydro. 

Going back to Dec. 8, 2007, the red arrows show several lakes that are open.  The open lakes stand out distinctly as black.   Lets zoom in and have a closer look in the next image.

Dec 8, 2007, zoomed in to look closer at some of those open lakes, shows with red arrows.  Dog Lake, wide open, is shows in a blue arrow, which we looked at above.  So going back 8 days from today (Dec 16) we get a chronology of ice formation in some lakes.  We see a general gradient of close up from north to south.  Some of the lakes open in this image are deep lake trout lakes, so they take longer to freeze than the shallower lakes.   


So based on a chronological look from Dec 8 to Dec 16, I can see some lakes freezing up, and some northern lakes fully covered the entire time.   Can I make decisions about safe ice from this?  Nope!   But it certainly helps give me an idea of what’s been going on.

Confounding the assessment is the fact that in this part of the country, we received a big dump of snow in the first week of December.  That’s not good for ice formation.  That deep snow insulated the ice when it was still thin, and will greatly slow its formation.  I have not been out yet, but no doubt most lakes are also covered in slush under the snow, making traveling conditions ugly.  I hope we get lots of extreme cold nights to thicken the ice, but we may have to deal with the slush until the end of February.   :(

As soon as I get out on some trips, I will report back with an update.  Let’s hear your reports!   :)
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Re: NW Ontario Lake Freeze-up Using MODIS Satellite Imagery
« Reply #1 on: December 17, 2007, 06:46:31 pm »
Excellent site Hoop, I book marked it, thanks. I plan on taking my first trip (solo) of 2008 the first weekend of Jan. I"ll post a trip report and pictures after I get back.