April 9, 2022: Satellite Saturday

A few Saturdays have gone by without the regular Satellite Saturday feature. There are a couple of reasons for this. Most worrisome, one of my two favourite satellites is offline at the moment. NASA’s Aqua satellite–which carries one of the MODIS cameras–has gone into Secure Mode. Maybe this has to do with solar activity, or perhaps it’s a technical problem of a different sort. At any rate, it hasn’t delivered any pictures since the end of March. NASA technicians are trying to get it functioning again.

The other reason is cloud cover. We’ve had a ton of it. So poor Terra, working without its twin, has had few chances to image Lake of the Woods. We finally had clear skies for a while yesterday, and Terra was able to capture this.

April 8th MODIS false-colour image from NASA’s Terra satellite.

If you click on this image, it won’t get bigger. But you will see a version with some location tags.

Remember, in the false-colour images, ice is pale blue and open water is black. Aside from the Winnipeg River, flowing towards the top of the picture, the only open water of note is the bit near town, and some at Big Narrows, just left of the center of the frame. There might be something over at Whitefish Bay, to the right of center in this picture. Significantly, there’s no water showing at south end of the lake, not even at the mouth of the Rainy River.

At times like this, I get curious to see how the situation compares to past years.

Here’s a mosaic I made up for today’s presentation at Common Ground. I had fun, by the way.

Common Ground – Volume III was released today. It contains all the stories of the Lake of the Woods Area from the last five Common Ground storytelling events. Copies are available at the Kenora Public Library and the Lake of the Woods Museum.

If you click on this picture you’ll see it full-screen. The resolution of the mosaic is 1920×1200.

Comparable false-colour images from 2012, 2014, 2017, 2018, 2021 and 2022.

These pictures are all from the end of March in recent years.

2012 was one of our earliest melts, as you can clearly see here. 2014 was the year Ice Patrol became a website, and it was dreadful: there’s so much snow in the woods that you can barely distinguish the lake. 2017 shows open water at Rainy River, Big Narrows and the Winnipeg River. There’s bare farmland on the American side, too. 2018 wasn’t ice free until May 14, and it was still very icy in late March. 2021 shows much less snow in the forest, and the thaw was over by April 24^th. This year most closely resembles 2018. We shall see.

Also worth mentioning: there’s been very little change between March 27 and April 8. That’s almost a fortnight without visible progress.

The future of NASA’s Terra and Aqua satellites is limited. They were designed to operate until “the early 2020’s”. Terra is low on fuel, and cannot correct it’s orbit like before. Aqua is having a time-out.

So I am exploring a new portal that offers satellite imagery from the European Space Agency’s Sentinel satellites, as well as Landsat satellites from NASA / USGS* and some others. I haven’t got the full hang of it yet, but I have made a start. I have learned that Sentinel 2 (there are 8 or 9 Sentinel satellites, and they are not identical) offers a Short-wave Infrared view that is similar to the images above. The good news is, the resolution is much higher. The bad news is, quite often the satellite only images narrow strips of Lake of the Woods. It’s a trade-off, you see: because the camera zooms in for good detail, it cannot easily cover huge swathes of ground. Or lake, in our case.

But here’s one recent success. You can click on this image to see a full-screen version. 

Sentinel 2 Short-wave infrared image of Lake of the Woods. March 28, 2022.

You might want to compare this image to the picture at the lower right of the mosaic above. That MODIS picture was taken just one day earlier, so you can get an idea of how the colour scheme compares. It seems clear that open water is black, but I’m not sure about the medium blues. Thin ice, slush, or surface water over ice?

I look forward to getting more familiar with this resource.

*The nine LandSat satellites are a joint project of the National Aeronautics and Space Administration (NASA) and the United States Geological Service (USGS).

The weather: we are having another warm spell, but the forecast is for significant snowfall next week, and cold temperatures into the Easter weekend. We have not yet reached the Inflection Point, because although we’ve had some above-freezing days, we keep sliding back to colder (and below normal) temperatures. An average high for today’s date is 7°C, and an average overnight low is about -4°C. That would put us on the right side of the Inflection Point, but we continue to fall short.

So we’re off to a late start. Other years with late Inflection Dates have run to fairly rapid thaws, because April weather tends to be pretty warm.

Here’s the Pancake Graph so you can see how this spring fits into that pattern.

You can click on this graph to make it larger and clearer.

Inflection to Thaw Calendar for 2003 to 2021.

We had a nasty cold winter, so if we don’t hit Inflection until after Easter, we’re going to need some good warm weather to stay on track for my first guess, which was that we’d be ice-free around May 11-15.

Signs of spring: I saw Mallards today, and the gulls are squawking. I have not yet seen a skunk or a bear. The bear part worries me a bit. We had a lot of bear activity in town last year because the berry crop was poor. That hard winter may have been too much for underfed hibernators. I fear there may have been a significant die-off. The snowdrift on my deck that was once the size of my Tucson is now down to just a couple of meagre* snow-shovels worth. Will it be able to hold on until next week’s reinforcements arrive?

I use mostly Canadian spellings: colour, favourite, meagre, and so on. I once had a short story rejected by an American magazine’s slush reader for “spelling mistakes.” This is my revenge.