Tag Archives: Siberia

Fires near the hottest city in the Arctic

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Something incredible happened in the Arctic a few days ago. Rather than type it out, I will let the World Meteorological Organization (WMO) explain it:

In case you’re wondering where Verkhoyansk is, you can look it up on Google Maps.

If that temperature is verified, it would be the hottest temperature ever recorded north of the Arctic Circle. To put that 38 °C into perspective, that was only 2 °C off from the high temperature in Phoenix, AZ on 20 June 2020 – a place where 40 °C is normal in the summer. It’s also worth reiterating how unusual it is for any location to average 8-10 °C (15-20 °F) above normal for an entire month. Russia as a whole – by far the largest country on Earth – has averaged 8 °C above normal for the entire first half of 2020!

If you clicked that last link, you saw an excerpt of the video above, plus more information on the unusual impacts of this heatwave. The clouds of mosquitoes. The collapsing buildings due to melting permafrost. (One of the largest oil spills ever in the Arctic happened in May, caused by melting permafrost.) And, an even more alarmist impact of the heat: “zombie fires“.

That’s right – if you didn’t have enough with the coronavirus or the murder hornets or the melting Arctic, you can now panic about zombie fires. In all seriousness, the silly name has been applied to the phenomenon of fires in peat bogs never really being fully extinguished, and continuing to smolder deep down below the ice and snow that covered it up all winter. Then, when a heatwave happens the next summer, the smoldering turns to re-ignition of the fire, and it once again appears on the surface.

Fires have been happening on a massive scale throughout Siberia this summer (and they’re probably not all zombie fires). But, we have a tool to observe them from satellite: Polar SLIDER.

I’m sure there may be a few of you who are already familiar with the website. For those who aren’t, here’s a brief synopsis: Polar SLIDER is designed to show the most recent VIIRS imagery available anywhere on Earth in as close to real-time as possible. Images from individual orbits from both Suomi-NPP and NOAA-20 are stitched together to create hemispheric composites that always feature the most recent imagery on top. The way the orbits work, when Suomi-NPP is crossing over into the Southern Hemisphere, NOAA-20 is crossing into the Northern Hemisphere (and vice versa). By combining imagery from both satellites, there is a ~50 minute refresh over the poles, giving a quasi-geostationary satellite view of each pole. Imagery is available at six different zoom levels, separated by factors of 2, so you can zoom in to see full resolution VIIRS imagery anywhere on Earth.

Here’s an example of Polar SLIDER, reduced in size to play well with this blog software, showing our GeoColor product (True Color imagery during the day, blended with the Day/Night Band and a low cloud detection algorithm at night) over Siberia on 23-24 June 2020:

VIIRS GeoColor animation (23-24 June 2020)
VIIRS GeoColor animation (23-24 June 2020)

How much smoke can you see? Did you count the plumes? Did you see the swirl in the smoke at about 70°N, 140°E? (For reference, Verkhoyansk is near 67°N, 133°E.)

That loop covers approximately 30 hours in the Arctic and, since we’re so close to the summer solstice, you can estimate the location of the Arctic Circle, even though it isn’t plotted.

Even those of you who have heard of (or seen) Polar SLIDER before might not be aware of the recent upgrades made in May 2020. For the first 18 months of its existence, Polar SLIDER had all 22 VIIRS channels (DNB, 16 M-bands, 5 I-bands) plus GeoColor (as shown in the loop above) and, occasionally, the I-band Natural Color (aka Day Land Cloud RGB) product. Now, we have added 10 new products, including the most popular RGB composites (the ones that are available from VIIRS, anyway) and two new RGBs for snow monitoring that utilize the 1.24 µm band that are not available on any geostationary satellite. (More information on those is available here.) We’ve also fixed the issues with the Natural Color RGB, making it a permanent fixture, rather than an anomaly.

Among the new products available on Polar SLIDER is what we call Natural Fire Color (and the National Weather Service calls “Day Land Cloud Fire RGB“), made from VIIRS bands I-1 (0.64 µm, blue), I-2 (0.86 µm, green) and I-4 (3.7 µm, red). As it is made from VIIRS I-bands, it is available at 375 m resolution around the globe. Here’s what it shows from 22-23 June 2020 over this part of Siberia:

VIIRS Day Land Cloud Fire RGB animation (22-23 June 2020)
VIIRS Day Land Cloud Fire RGB animation (22-23 June 2020) – click to play

This animation is too large for WordPress. You have to click on it to get it to play. But, I couldn’t resist showing the full resolution imagery. Also, a note about the timestamps on Polar SLIDER: it takes ~50 min for each satellite to cover each hemisphere, and the image times displayed on Polar SLIDER represent the Equator-crossing time as the satellite leaves the hemisphere, which is most likely not the time the satellite was viewing the area you’re looking at.

The Natural Fire Color/Day Land Cloud Fire loop covers a ten hour period from ~ 8:00 AM to 6:00 PM local time (depending on where you are in the scene, it might be 7:00 AM to 5:00 PM), during which time there were 11 consecutive VIIRS overpasses over this region between the two satellites. This is a textbook example of how fires typically die down at night (or, at least, when the sun is hovering over the horizon) and intensify during the heating of the day.

Of course, you can get a better idea of the intensity of the fires by looking at the Fire Temperature RGB, which is also now on Polar SLIDER:

VIIRS Fire Temperature RGB animation (22-23 June 2020)
VIIRS Fire Temperature RGB animation (22-23 June 2020) – click to play

Once again, you have to click on the animation to get it to play.

The Fire Temperature RGB is made with VIIRS M-bands (750 m resolution), so the fires don’t look as crisp when viewed at the 375 m zoom level. But, since it uses more information from fire-sensitive bands in the shortwave IR, it provides a qualitative estimate of fire intensity, not just the locations of the active hot spots. (As fires become more intense, their color changes from red to orange to yellow to white in the Fire Temperature RGB.)

Other differences to note between the two loops are: the Natural Fire Color RGB shows the reddish-brown burn scars more clearly amongst a background of green vegetation; it shows the bluish smoke more clearly; and it shows ice in the Arctic Ocean, which appears nearly black in the Fire Temperature RGB. We’ve covered all of this before, both here and elsewhere. We’ve also covered the importance of VIIRS’ high resolution (compared to geostationary satellites) when it comes to fires before. But, it’s worth looking at again. Compare the loops above with the view from the Advanced Himawari Imager (AHI) on Himawari-8:

AHI Day Land Cloud Fire RGB animation (23 June 2020)
AHI Day Land Cloud Fire RGB animation (23 June 2020) – click to play
AHI Fire Temperature RGB animation (23 June 2020)
AHI Fire Temperature RGB animation (23 June 2020) – click to play

You can find a loop of the AHI GeoColor showing the smoke plumes here.

It’s difficult to identify any fires in the AHI Natural Fire Color/Day Land Cloud Fire RGB, given the resolution of the 3.9 µm channel is 2 km at the Equator (more like 3-6 km in this part of the world) – not 375 m like the VIIRS version. Hot spots show up better in the AHI Fire Temperature RGB this far north, because this combination of channels makes the background surface appear darker relative to the pixels with active fires in them, whereas the background is brighter in the Natural Fire Color RGB.

Lastly, because I mentioned new RGBs for snow on Polar SLIDER, one of them has an interesting artifact when it comes to fires. The Snow RGB originally developed by MétéoFrance utilizes the 2.25 µm band as the blue component, making hot spots appear blue:

VIIRS MeteoFrance Snow RGB composite of channels M-11, M-8 and M-7 (23 June 2020)
VIIRS MétéoFrance Snow RGB composite of channels M-11, M-8 and M-7 (23 June 2020)

Of course, if you’re looking for fires, don’t reach for the Snow RGB. But, someone, somewhere is going to be looking at the Snow RGB when they spot a couple of bright blue pixels and wonder, “What’s going on here?” And, I’m here to say, “Those are moderately intense fires.”

Rivers of Ice

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Oh, Yakutsk! It has been a long time – 2012, to be exact – since we last spoke about you (on our sister blog). It was a different time back then, with me still referring to the EUMETSAT Natural Color RGB as “pseudo-true color”. (Now, most National Weather Service forecasters know it as the “Day Land Cloud RGB”). VIIRS was a only a baby with less than one year on the job. Back then, the area surrounding the “Coldest City on Earth” was on fire. This time, we return to talk about ice.

You see, rivers near the Coldest City on Earth freeze during the winter, as do most rivers at high latitudes. Places like the Northwest Territories, the Yukon, Alaska and Siberia use this to their advantage. Rivers that are frozen solid can make good roads, a fact that has often been overly dramatized for TV. Transporting heavy equipment may be better done on solid ice in the winter than on squishy, swampy tundra in the summer. But, that comes with a cost: ice roads only work during the winter.

In remote places like these, with few roads, rivers are the lifeblood of transportation – acting as roads during the winter and waterways for boats during the summer. But, what about the transition period that happens each spring and fall? Every year there is a period of time where it is too icy for boats and not icy enough for trucks. Monitoring for the autumn ice-up is an important task. And, perhaps it is more important to monitor for the spring break-up of the ice, since the break up period is often associated with ice jams and flooding.

We’ve covered the autumn ice up before on this blog, but VIIRS recently captured a great view of the spring break up near Yakutsk, that will be our focus today.

We will start with the astonishing video captured by VIIRS’ geostationary cousin, the Advanced Himawari Imager (AHI) on Himawari-8 from 18 May 2018:

The big river flowing south to north in the center of the frame is the Lena River. (Yakutsk is on that river just south of the easternmost bend.) The second big river along the right side of the frame is the Aldan River, which turns to the west and flows into the Lena in the center of the frame.

Now that you are oriented, take a look at that video again in full screen mode. If you look closely, you will see a snake-like section of ice flowing from the Aldan into the Lena. This is exactly the kind of thing river forecasters are supposed to be watching for during the spring!

Of course, this is a geostationary satellite, which provides good temporal resolution, but not as good spatial resolution. The video is made from 1-km resolution imagery, but we are looking at high latitudes on an oblique angle, so the resolution is more like 3-4 km here. (Note: the scene in the video above is approximately the same latitude as the Yukon River delta, so this acts as a good preview of what GOES-17 and its Advanced Baseline Imager [ABI] will offer.) So, how does this look from the vantage point of VIIRS, which provides similar imagery, but at 375 m resolution? See for yourself:

(You will have to click on the image to get the animation to play.)

Animation of VIIRS Natural Color RGB composite of channels I-1, I-2 and I-3 (18 May 2018)
Animation of VIIRS Natural Color RGB composite of channels I-1, I-2 and I-3 (18 May 2018)

This animation includes both Suomi NPP and NOAA-20 VIIRS. That gives us ~50 min. temporal resolution to go with the sub-kilometer spatial resolution. Eagle-eyed viewers can see how the resolution changes over the course of the animation, as the rivers start out near the left edge of the VIIRS swath (~750 m resolution), then on subsequent orbits, the rivers are near nadir (~375 m resolution) and then on the right edge of the swath (~750 m resolution again). In any case, this is better spatial resolution than AHI can provide (or ABI will provide) at this latitude.

One thing you can do with this animation is calculate how fast the ice was moving. I estimated the leading edge of the big “ice snake” moved about 59 pixels (22.3 km at 375 m resolution) during the 3 hour, 21 minute duration of the animation. That works out to an average speed of 6.7 km/hr (3.6 knots), which doesn’t seem unreasonable. Counting up pixels also indicates our big “ice snake” is at least 65 km long, and the Aldan River is nearly 3 km wide in its lower reaches when it meets the Lena River. That is in the neighborhood of 200 km2 of ice!

That much ice moving at over 3 knots can do a lot of damage. Just look at what the ice on this much smaller river did to this bridge:

(Make sure you watch it all the way to the end!)