April 30, 2022: Satellite Saturday

Well, it’s raining again. We’re setting records for April precipitation as I write this.

That means the last couple of days haven’t been good for satellite photos, but we got an exceptionally good look at the lake on Wednesday. Sentinel 2 is a European Space Agency satellite that takes high resolution pictures. It doesn’t come our way every day, and when it does, it often images only part of the lake because of it’s narrow field of view.

But on Wednesday, everything aligned.

You can click on these pictures to see them at higher resolution!

Sentinel 2 image of Lake of the Woods, in true colour.

Yes, that’s a colour photo. There’s just not a lot of green in our landscape yet.

But if you’d like something a bit more vibrant, Sentinel 2 also offers a short-wave infrared option.

Sentinel 2 image of Lake of the Woods, in short-wave infrared.

Note the scale (5km) in the bottom right corner. But wait, there’s more good news. This satellite can show more detail than this. I can’t upload a picture of the whole lake at the highest resolution; the file is too big. But I can zoom in for a better look at the north part of the lake, and upload that.

Don’t forget to click on these images to see the full-screen version. Click on that to see the picture’s full resolution.

Sentinel 2 image of the northern part of Lake of the Woods in short-wave infrared.

So on this image, I thought I noticed something. In a recent aerial photo from Tom Hutton, taken the same day, you could see rotten ice south of the Keewatin Channel, extending past Town Island towards Scotty.

Let’s zoom in even tighter on that area, to a 1km scale.

Sentinel 2 image of the Wendigo and Bigstone Bay in short-wave infrared.

Now we can clearly see the dark blotches of softening ice, extending from the open water in Keewatin Channel and Second Channel at the upper left, towards Scotty Island near the middle of the frame.

This is the ice that I expect to yield next.

It’s also worth noting that there are multiple tiny patches of water visible in the vicinity of Middle Island, at Eagle Pass at the east end of Hay Island, and near Railroad Island, south of Hay.

Rapidly rising lake levels, and more importantly, the increasing outflows through the Norman Dam* that the rising water necessitates, should help to erode more ice, starting in these areas with significant currents.

*The Lake of the Woods Control Board strives to keep the lake levels within specified limits. A month ago, the lake was pretty low. Multiple Colorado lows have dumped a lot of first snow, and then rain in the lake’s drainage basin. The board reports that the average lake level has been rising by over an inch a day, (25cm in a week) and will continue at close to that rate for several more days. In the meantime, outflow through the dam has gone from 450 cubic metres per second three weeks ago to more than double that, at 925. Fun fact: a cubic metre of fresh water masses one tonne.

So enjoy the rain!

9 thoughts on “April 30, 2022: Satellite Saturday

  1. On that Sentinel browser, take a look at the NDWI layer. This layer greatly highlights differences between hard ice, snow, slush, and open water. Fissures also stand out.

    • Cool! I tried that one earlier, when there was still a thick snow cover, and it didn’t reveal much. I’ll look again.

  2. The good thing about the amount of snow we had, was that it insulated the ice. There definately was not as much ice as some years, so the ice may go fast! We saw about 34″ of ice, and normally it’s well over 40″, some years 48″

    Any thoughts on this???

    • This is an excellent point. I wasn’t sure if the early snow slowed down the formation of ice, and I didn’t get any ice measurements until yours. Thinner ice than expected could make all the difference.

  3. I have pictures of the flow output at the Norman dam , would you like them for the site?

    Sent from my iPhone

    >

    • Yes please. I hike down there and look once in a while, but I don’t always take pictures.

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