Beginning of Autumn in the Great Lakes

Have you noticed it? The seasons are changing (for the mid- and high latitudes, at least). Days are getting shorter (or longer if you live in the upside-down hemisphere). This time of year, if you live in Alaska or Scandinavia or similar high latitude locations, you lose about 5-10 minutes of available daylight each day. (That’s between a half and one hour per week!) You may have noticed by the fact that your neighbor no longer mows the lawn at 11:00 PM because it’s still bright outside and hey, why not? I wasn’t going to sleep anyway.

Closer to home – in the mid-latitudes – loss of daylight is more like 1-3 minutes per day, which isn’t as noticeable. But, one day, you watch the sun set and look at the clock and realize that it’s only 6:30 PM and you think, didn’t it used to be light out later than this?

That’s not the only way to tell the seasons are changing. For one, there’s the arrival of snow. (Although parts of Montana, Wyoming and South Dakota received snow earlier this year while it was still technically summer.)  And, for two, there’s what VIIRS observed on 27 September 2014:

VIIRS True Color RGB composite of channels M-3, M-4 and M-5, taken 17:57 UTC 27 September 2014

VIIRS True Color RGB composite of channels M-3, M-4 and M-5, taken 17:57 UTC 27 September 2014

In case it’s not obvious, here’s what VIIRS saw earlier in the month (8 September 2014):

VIIRS True Color RGB composite of channels M-3, M-4 and M-5, taken 17:13 UTC 8 September 2014

VIIRS True Color RGB composite of channels M-3, M-4 and M-5, taken 17:13 UTC 8 September 2014

Notice anything different between the two images? (Remember to click on the images, then on the “1735 x 1611″ links below the banner to see the images in full resolution.)

That’s right – the loss of daylight leads to one of the benefits of autumn: fall foliage. VIIRS True Color imagery shows, quite clearly, that the leaves of New England and eastern Canada have changed color. Forests that were green in early September have turned orange, red and brown by the end of the month.

Another thing you may have noticed comparing those two images: the change from green to beige in the area around Montreal, Quebec. This is another sign of autumn: the fall harvest. This is a productive agricultural region in eastern Canada, and what you are seeing is the green vegetation (crops) being harvested, leaving behind bare dirt.

True Color imagery is useful for observing the changing foliage and the harvest because it is designed to reproduce what we humans observe on the ground. The red, green and blue components of the RGB composite are channels in the red (M-5, 0.67 µm), green (M-4, 0.55 µm) and blue (M-3, 0.48 µm) portions of the electromagnetic spectrum. When leaves change from green to red, the True Color RGB detects that.

Now, you’ve probably known since elementary school (or at least middle school) that leaves change color because of chlorophyll. And, unless you became a botanist, that is probably the limit of your knowledge on the subject. But, there’s a lot of interesting chemistry that goes on inside a leaf (and the whole tree) that determines it’s color.

Of course, leaves are green because they contain chlorophyll. Chlorophyll is necessary for plants to convert sunlight into sugar. Chlorophyll, by necessity due to it’s job, is highly absorbing of visible-wavelength radiation, although it is slightly less absorbing of green wavelengths. Green light is therefore preferentially reflected out of the leaves and into your eye, and the leaves appear green.

When the sunlight goes away and the air becomes cold, deciduous trees go into hibernation. They break down the chlorophyll in their leaves, and send the remaining nutrients down into the trunk and roots. This exposes the carotinoids that were in the leaves and these carotinoids have a yellow or orange color – they preferentially reflect yellow and/or orange wavelengths. Red colors come from a pigment called anthocyanin, which was recently discovered to be a sort of “plant sunscreen”.

Now, utilizing sunscreen when you get all your energy from the sun may sound silly but, recent studies have shown that anthocyanin protects the leaves from sun damage once the chlorophyll is gone so that the tree has time to extract all the nutrients out of the leaves before they fall off. Trees in poor soil conditions are more likely to turn red in the fall as a natural defense mechanism – they need to store all the nutrients they can from their leaves, since they aren’t getting them from the soil.

Oak and other leaves turn brown in the fall because of a buildup of tannin (link to PDF file), which is a waste product. Brown leaves are full of plant poo! Think about that the next time you go on a fall color driving tour.

Now, back to the satellite science before the biologists come after me for grossly oversimplifying leaf chemistry. I’ve often talked about the Natural Color RGB composite as being similar to the True Color RGB in many instances (except for the detection of ice and snow). So, what does that look like here?

Here’s the VIIRS Natural Color RGB from 8 September 2014:

VIIRS Natural Color RGB composite of channels M-5, M-7 and M-10, taken 17:13 UTC 8 September 2014

VIIRS Natural Color RGB composite of channels M-5, M-7 and M-10, taken 17:13 UTC 8 September 2014

And here’s the same RGB from 27 September 2014:

VIIRS Natural Color RGB composite of channels M-5, M-7 and M-10, taken 17:57 UTC 27 September 2014

VIIRS Natural Color RGB composite of channels M-5, M-7 and M-10, taken 17:57 UTC 27 September 2014

Why does the vegetation still appear green when the leaves have changed color? Because we’ve made vegetation artificially appear green. The Natural Color RGB uses the red wavelength visible channel (M-5, 0.67 µm) as the blue component. The green component is a near-infrared channel (M-7, 0.87 µm), where plants are their most reflective – leaves and other plant tissues don’t absorb radiation at this wavelength. The red component is a longer wavelength channel (M-10, 1.61 µm) where the water inside the leaves starts to absorb radiation and the reflectance goes down. Cellulose and lignin also weakly absorb at 1.61 µm. The bottom line is, plants are highly reflective at 0.87 µm regardless of how healthy the plant is, or what color the leaves are – so they will always appear green in the Natural Color images.

You might also note the one difference (apart from clouds) that shows up between the two Natural Color images is the lack of green surrounding Montreal in the 27 September image. This is another sign of the fall harvest: the highly reflective plants have been removed and all that’s left is dirt, which is not as reflective. That’s why those areas appear more brown in the later image.

If we look a bit further west in the True Color imagery from 27 September 2014, the fall color really stands out:

VIIRS True Color RGB composite of channels M-3, M-4 and M-5, taken 17:57 UTC 27 September 2014

VIIRS True Color RGB composite of channels M-3, M-4 and M-5, taken 17:57 UTC 27 September 2014

Fall colors are visible from the Adirondacks of Upstate New York and Quebec to the Upper Peninsula of Michigan. The most vivid fall color is in Ontario – both in the area of Sault Ste. Marie and in the area of Algonquin Provincial Park, the oldest provincial park in Canada. Every autumn, the Friends of Algonquin Park post pictures of the fall colors, including this shot from 27 September 2014 showing just what VIIRS was seeing. Amazing colors!

We have sunny days, cool nights and plant survival techniques to thank for that.

 

BONUS:

Here’s a desktop wallpaper that’s zoomed in on the above image and cropped to the most popular screen resolution (1366×768):

VIIRS True Color RGB Composite Desktop Wallpaper (17:57 UTC 27 September 2014)

VIIRS True Color RGB Composite Desktop Wallpaper (17:57 UTC 27 September 2014). This image fits monitors with a 16:9 ratio and is optimized for 1366x768 screen resolutions.

Make sure you click on the image, then on the “1366 x 768″ link below the banner to get the full resolution image. Then you can right-click on the image and choose “Set as desktop background” to save it as your new desktop wallpaper.

Investigating Mysteries of the Deep, Dark Night

Conspiracy theorists will tell you that conspiracies exist everywhere; that they’re part of daily life; and that most people are ignorant of all the attempts by various governments around the world to covertly control every facet of your life. Only they know the truth. But, that’s just what they want you to believe! Conspiracy theorists are simply manipulating you in order to control you and create a New World Order! Wake up!

Full disclosure: I am subsidized by the U.S. government to inform people of the capabilities and uses of the satellite instrument called VIIRS and today I’ll show you how that satellite instrument can help separate fact from fiction when it comes to the latest conspiracy theory. (Of course, working for the government means I could be part of the conspiracy!  Mwa ha ha!)

During the last week of August 2014, I was sent this link to a story from a pilot/photographer who captured “the creepiest thing so far” in his long flying career. I’ll quote his initial post again in its entirety here (for those of you too lazy to click on the links):

Last night [24 August 2014] over the Pacific Ocean, somewhere South of the Russian peninsula Kamchatka I experienced the creepiest thing so far in my flying career. After about 5 hours in flight we left Japan long time behind us and were cruising at a comfortable 34.000ft with about 4,5 hours to go towards Alaska.
We heard via the radio about earthquakes in Iceland, Chile and San Francisco, and since there were a few volcanos on our route that might or might not be going off during our flight, we double checked with dispatch if there was any new activity on our route after we departed from Hongkong.

Then, very far in the distance ahead of us, just over the horizon an intense lightflash shot up from the ground. It looked like a lightning bolt, but way more intense and directed vertically up in the air. I have never seen anything like this, and there were no flashes before or after this single explosion of light.

Since there were no thunderstorms on our route or weather-radar, we kept a close lookout for possible storms that might be hiding from our radar and might cause some problems later on.

I decided to try and take some pictures of the night sky and the strange green glow that was all over the Northern Hemisphere. I think it was sort of a Northern Lights but it was much more dispersed, never seen anything like this before either. About 20 minutes later in flight I noticed a deep red/orange glow appearing ahead of us, and this was a bit strange since there was supposed to be nothing but endless ocean below us for hundreds of miles around us. A distant city or group of typical Asian squid-fishing-boats would not make sense in this area, apart from the fact that the lights we saw were much larger in size and glowed red/orange, instead of the normal yellow and white that cities or ships would produce.

The closer we got, the more intense the glow became, illuminating the clouds and sky below us in a scary orange glow. In a part of the world where there was supposed to be nothing but water.

The only cause of this red glow that we could think of, was the explosion of a huge volcano just underneath the surface of the ocean, about 30 minutes before we overflew that exact position.

Since the nearest possible airport was at least 2 hours flying away, and the idea of flying into a highly dangerous and invisible ash-plume in the middle of the night over the vast Pacific Ocean we felt not exactly happy. Fortunately we did not encounter anything like this, but together with the very creepy unexplainable deep red/orange glow from the ocean’s surface, we felt everything but comfortable. There was also no other traffic near our position or on the same routing to confirm anything of what we saw or confirm any type of ash clouds encountered.

We reported our observations to Air Traffic Control and an investigation into what happened in this remote region of the ocean is now started.

If you go back and click on the link, you’ll see he posted several pictures of the mysterious red lights along with more detailed information about where and when this occurred. To save you some time, here is a representative picture (taken at 11:21 UTC 24 August 2014). And here is the location of the aircraft when they saw the lights.

There are three parts to this story: 1) the bright flash of light that looked like lightning coming up from the surface; 2) the aurora-like features in the sky; and 3) the red and orange lights from the clouds below that appeared to be larger than ordinary ship lights.

Since the story was first posted, people from all over commented on what they thought the lights were and the pilot has been updating his webpage to cover the most common and/or most likely explanations. The media picked up the story and used it to claim the world was coming to an end. Existing theories range from UFOs (unidentified flying objects) and UUSOs (unidentified under-surface objects) operated by space aliens to covert military operations to spontaneously-combusting methane bubbling out of the ocean to “earthquake lights“. The pilot himself initially thought it was an underwater volcanic eruption.

So, can VIIRS shed light on what was going on? Yes – at least, on #2 and #3. VIIRS passed over the area in question at 15:35 UTC on 24 August, which is about 4 hours after the pilot took his pictures. This means VIIRS can’t say anything about the lightning-like flash that was observed. So #1 is unexplained.

As for #2 – the aurora-like features in the sky – those are simply airglow waves. We’ve discussed airglow and airglow waves before here and here.

Now, onto #3 where VIIRS is most informative: the mysterious surface lights. I mentioned the VIIRS overpass at 15:35 UTC on 24 August. Here’s what the Day/Night Band (DNB) saw:

VIIRS Day/Night Band image from 15:35 UTC 24 August 2014.

VIIRS Day/Night Band image from 15:35 UTC 24 August 2014.

Look at 47.5°N latitude and 159°E longitude. (You can click on the image, then on the “4329 x 2342″ link below the banner to see the full resolution image.) Those are the lights the pilot saw! (Note also that this night was near new moon, so any illumination of the clouds in that area comes from airglow. Light in the northeast corner of the image is twilight from the approaching sunrise.)

Now, VIIRS also has bands in the short-, mid- and long-wave infrared (IR). Surely, they must have seen the heat signature put out by a volcanic eruption, right? Not necessarily. The pilot’s photographs clearly show the lights shining through a layer of clouds, and it doesn’t take much cloud cover to obscure heat signatures at these wavelengths. But, for completeness, here are the observed brightness temperatures at 3.7 µm (channel M-12) and 10.7 µm (channel M-15):

VIIRS M-12 image from 15:35 UTC 24 August 2014

VIIRS M-12 image from 15:35 UTC 24 August 2014

VIIRS M-15 image from 15:35 UTC 24 August 2014

VIIRS M-15 image from 15:35 UTC 24 August 2014

I don’t see any hotspots in either of those images near the location of the lights. But, as I said, this doesn’t disprove the presence of flaming methane or volcanic activity because of possible obscuration by clouds. (Note that the clouds are easier to see in the DNB image than either of the IR images because there is no thermal contrast between the clouds and the open ocean for the IR images to take advantage of. There is, however, reflection of airglow light available to provide contrast in the DNB.)

What about the night before? The night after? Were the lights still there?

Here’s the DNB image from 15:54 UTC 23 August 2014 (aka the night before):

VIIRS DNB image from 15:54 UTC 23 August 2014

VIIRS DNB image from 15:54 UTC 23 August 2014

The light is there in pretty much the same place, although it looks like one big circle instead of a number of smaller lights. What is going on? Once again, it’s clouds. This time, the longwave IR shows we have optically thicker and/or an additional layer of high clouds over the lights:

VIIRS M-15 image from 15:54 UTC 23 August 2014

VIIRS M-15 image from 15:54 UTC 23 August 2014

Optically thicker clouds scatter and diffuse the light more, and what you are seeing in the DNB image is the area of clouds surrounding the light source that scatter the light to the satellite. See how clouds scatter the city lights of the U.S. Midwest in this comparison between the DNB and M-15 from 07:42 UTC 2 September 2014:

(You may have to refresh the page if this before/after image trick doesn’t work.)

It’s not that Chicago, Illinois and Gary, Indiana extend that far out into Lake Michigan or that the map is not plotting correctly. It’s that the optically thicker clouds over the southern end of the lake scatter more of the light back to the satellite (and over a larger area than the lights themselves), making it appear that the light is coming from over the lake.

Similarly, scattering in the clouds makes the individual “mystery lights” over the Pacific Ocean appear to be one large area of light, instead of a number of smaller lights.

How do the lights look on 25 August 2014 (aka the night after)? Here’s the DNB image:

VIIRS DNB image from 15:18 UTC 25 August 2014

VIIRS DNB image from 15:18 UTC 25 August 2014

Did you notice that? The lights aren’t in the same place as before. They moved. In fact, I tracked these lights in the DNB for two weeks. And I got this result:

Do volcanoes move around from day to day? I think we can safely say the pilot was not observing a volcanic eruption.

Now, I don’t know much about spontaneously combusting methane bubbles in the ocean, but I doubt they are this frequent. The pilot found another pilot’s report of methane burning over the ocean from 9 April 1984 (which also occurred during a flight from Japan to Alaska) but, that was during the day and it was the resulting cloud that was spotted, not the actual flames. There is no evidence of clouds being produced by these lights over this two week period. There also isn’t much evidence from seismic activity over this period to justify earthquake lights.

Another theory put forth was meteorites but, again, it seems highly improbable that VIIRS would be capturing this many meteorites hitting this localized area of the Pacific Ocean every night for two weeks. Plus, they would have to be pretty large meteors to appear as large as these lights.

Unless you believe in UFOs (or UUSOs), that leaves only one question: why were the pilots of this flight so quick to dismiss ships? The DNB has seen ships on the ocean before, and they look a lot like this. (You can find examples of individual boats observed by the DNB here and an example of larger squid boat operations here.)

It is true that most squid boats use white or greenish light and the pictures clearly show red and orange lights coming up through the clouds. But military ships are known to use red lights at night, at least, according to Yahoo! Answers.

If it looks like a fleet of ships and moves like a fleet of ships, I’m guessing it’s a fleet of ships. Unless, of course, it’s a gam of sharks with freakin’ laser beams attached to their heads.

 

When Canada Looks Like China

No, I’m not talking about Chinatown in Vancouver. Or Chinatown in Toronto. Or any other Chinatown in Canada. I’m talking about this. Or, more exactly, this. Poor air quality is making it difficult to breathe in Canada and elsewhere.

Unlike the situation in China, you can’t really blame the Canadians for their poor air quality. (Unless, of course, some serial arsonist is wreaking havoc unfettered.) You see, it has been an active fire season in western Canada, to put it mildly. Here’s a not-so-mild way to put it. That article, from 3 July 2014, put the number of fires in the Northwest Territories alone at 123, with most of them caused by lightning. But, after a check of the Northwest Territories’ Live Fire Map on 30 July 2014 it looks like there are more than that:

"Live Fire Map" from NWTFire, acquired 17:00 UTC 30 July 2014

"Live Fire Map" from NWTFire, acquired 17:00 UTC 30 July 2014. This is a static image, not an interative map.

I estimated 160-170 fires in that image (assuming I didn’t double count or miss any). How many fires can you count?

At one point earlier in July, it was estimated that battling the fires was costing $1 million per day! The fires have been impacting power plants, causing power outages, impacting cellular and Internet service, closing the few roads that exist that far north, and doubling the number of respiratory illnesses reported in Yellowknife, the territory’s capital.

It’s no secret that this area is sparsely populated. At last count, the territory had roughly 41,000 residents in 1.3 million km2. (Fun fact: the Northwest Territories used to make up 75% of the land area of Canada. It has since been split up among 5 provinces and into two other territories. With the formation of Nunavut in 1999, it was reduced to being only twice the size of Texas.) If so few people live there, why should we care if they have a few fires?

If you are so heartless as to ask that question, you are also short-sighted and selfish. For one, I already explained the damage that the fires are doing. For two, fires like these impact more than just the immediate area and more than just Canada. Let me explain that but, first, let me show you the fires themselves – as seen by VIIRS – over the course of the last month.

Animation of VIIRS Fire Temperature RGB images 24 June - 25 July 2014

Animation of VIIRS Fire Temperature RGB images 24 June - 25 July 2014

You will have to click on the above image, then on the “933×700″ link below the banner to see the animation at full resolution. It is 15 MB, so it may take a while to load if you have limited bandwidth. What you are looking at is the Fire Temperature RGB in the area of Great Slave Lake, the area hardest hit by this fire season. There are a lot of fires visible over the course of the month!

See how the larger fires spread out? They look like the large scale version of an individual flame spreading out on a piece of paper. (Don’t try to replicate it at home. I don’t want you catching your house on fire!) Of course, the spread of the fires is dependent on the winds, humidity, moisture content in the vegetation, and the firefighters – if they’re doing their job.

Now, these weren’t the only fires in Canada during this time. Check out this Fire Temperature RGB image from 15 July 2014 and see how many (rather large) fires there are in British Columbia and Saskatchewan:

VIIRS Fire Temperature RGB composite of channels M-10, M-11 and M-12, taken 21:08 UTC 15 July 2014

VIIRS Fire Temperature RGB composite of channels M-10, M-11 and M-12, taken 21:08 UTC 15 July 2014

Make sure to click through to the full resolution version. I counted 9 large fires in British Columbia, 1 in Alberta (partially obscured by clouds) and 6 in Saskatchewan. If you look closely, you might also spot 3 small fires in Washington plus more small fires in Oregon. (“Small” here is compared to the fires in Canada.)

Now, all these fires means there must be smoke and, because VIIRS has channels in the blue and green portions of the visible spectrum, we can see the smoke clearly. This is one of the benefits of the True Color RGB (in addition to what we discussed last time). If I tried to create another animation, like I did above, showing the extent of the smoke plumes it would be so large it might crash the Internet. Instead, here are some of the highlights (or low-lights, depending on your point of view) from the last month.

On 6 July 2014, the smoke is largely confined to the area around Great Slave Lake:

VIIRS True Color RGB composite of channels M-3, M-4 and M-5, taken 20:35 UTC 6 July 2014

VIIRS True Color RGB composite of channels M-3, M-4 and M-5, taken 20:35 UTC 6 July 2014

The very next day (7 July 2014) the smoke is blown down into Alberta and Saskatchewan (almost as far south as Calgary and Saskatoon):

VIIRS True Color RGB composite of channels M-3, M-4 and M-5, taken 20:16 UTC 7 July 2014

VIIRS True Color RGB composite of channels M-3, M-4 and M-5, taken 20:16 UTC 7 July 2014

One day later (8 July 2014) smoke is visible down into Montana, North Dakota and beyond the edge of the image in South Dakota (a distance of over 2000 km [1200 miles] from the source!):

VIIRS True Color RGB composite of channels M-3, M-4 and M-5, taken 19:57 UTC 8 July 2014

VIIRS True Color RGB composite of channels M-3, M-4 and M-5, taken 19:57 UTC 8 July 2014

 

On the 12th of July, you could see a single smoke plume stretching from Great Slave Lake all the way into southwestern Manitoba (plus smoke over British Columbia from their fires):

VIIRS True Color RGB composite of channels M-3, M-4 and M-5, taken 20:23 UTC 12 July 2014

VIIRS True Color RGB composite of channels M-3, M-4 and M-5, taken 20:23 UTC 12 July 2014

When the fires really get going in British Columbia a few days later, the smoke covers most of western Canada. On 15 July 2014, smoke is visible from the state of Washington to the southern reaches of Nunavut and Hudson Bay:

VIIRS True Color RGB composite of channels M-3, M-4 and M-5, taken 19:27 UTC 15 July 2014

VIIRS True Color RGB composite of channels M-3, M-4 and M-5, taken 19:27 UTC 15 July 2014

One day later (16 July 2014), and it appears that smoke covers 2/3 of Alberta, nearly all of Saskatchewan, all of western Manitoba, southern Nunavut, southeastern Northwest Territories, and most of Montana and North Dakota. There is also smoke over Washington, Oregon and northern Idaho:

VIIRS True Color RGB composite of channels M-3, M-4 and M-5, taken 20:48 UTC 16 July 2014

VIIRS True Color RGB composite of channels M-3, M-4 and M-5, taken 20:48 UTC 16 July 2014

A quick estimate puts the area of smoke in the above image at 2.5 million km2, which is roughly a third the size of the contiguous 48 states!

With renewed activity in the fires in the Northwest Territories last week, the smoke was still going strong over Canada, impacting Churchill, Manitoba (home of polar bears and beluga whales):

VIIRS True Color RGB composite of channels M-4, M-4 and M-5, taken 20:17 UTC 23 July 2014

VIIRS True Color RGB composite of channels M-4, M-4 and M-5, taken 20:17 UTC 23 July 2014

I guess if the melting polar ice caps don’t kill off the polar bears, they can still get cancer from all this smoke. Maybe the “world’s saddest polar bear” will want to stay in Argentina.

I should add that some of my colleagues at CIRA and I have sensitive noses and were able to smell smoke right here in town (Fort Collins, Colorado) earlier this month. Plus, there were a few smoky/hazy sunsets. (Although it should be clarified that we don’t know if it was from the fires in Canada or the fires in Washington and Oregon. There weren’t any fires in Colorado at the time.) Nevertheless, the areal coverage and extent of the smoke from fires like these is immense, and can have impacts thousands of miles away from the source. And, it’s all carbon entering our atmosphere.

 

UPDATE (8/1/2014): Colleagues at CIMSS put together this image combining two orbits of data over North America from yesterday (31 July 2014), where you can see smoke stretching from Nunavut all the way down to Indiana, Ohio and West Virginia. There may even be some smoke over Kentucky and Tennessee. Witnesses at CIMSS reported very hazy skies across southern Wisconsin as a result.

The Rise of the Paraguay Brings Down Paraguay

When was the last time you heard anything about Paraguay? Nope – they weren’t in the World Cup, that was Uruguay. (Paraguay actually finished last out of all South American teams when it came to World Cup qualifying. Sorry to remind you, Paraguayans.) A quick perusal of the web indicates that the country has a history of isolationism, so it may not come as a surprise that news out of Paraguay is few and far between.

For you non-Paraguayans in the audience: How many of you knew that Paraguay was the richest nation in South America in the mid-1800’s? Paraguay held that title right up to the point that they tried to keep Brazilian influence out of a civil war in Uruguay. That kick-started the War of the Triple Alliance, which ultimately killed more than half the population of Paraguay, strengthened Argentina as a nation, and is credited with bringing about the end of slavery in Brazil. Paraguay has never been the same since. It became the poorest country in the region – a title it has held, pretty much, through today. This has caused one reporter to say (in one of the links above) that, to Paraguayans, success is a prelude to danger.

When the national football team scores, “it makes us nervous and we panic.”

But, this isn’t a metaphor for the title of this post. The title refers to Paraguay: the River (Rio Paraguay), which has brought the worst flooding in decades to Paraguay: the Country, and displaced more than 200,000 Paraguayans. Flooding has also occurred on the Rio Paraná – the second longest river in South America – and has impacted hundreds of thousands of people in Brazil and Argentina. (You won’t get me to say that it has impacted a Brazilian people – because that is an awful, overused joke. Oh, wait. Ignore what I said I wasn’t going to say.)

Just look at what the flooding did to Iguazú Falls – one of the wonders of the world you never heard about – on the border between Argentina and Brazil:

There are more pictures of the flooding at the falls here. Iguazú Falls is located at the head of a narrow canyon called the Devil’s Throat, where water levels were reported to be 16 meters (52 feet) above normal! It is said that this is the worst flooding since 1982-1983. (That flood event killed 170 people.)

As shown before, VIIRS is capable of viewing widespread flooding. So, what does VIIRS tell us about this flood? As it turns out, both the “Natural Color” RGB composite and the “True Color” RGB composite provide unique information, so let’s take a closer look.

If you simply want to see where the water is, look no further than the “Natural Color” RGB composite. The “Natural Color” composite uses the high-resolution bands I-01 [0.64 µm; blue], I-02 [0.87 µm; green] and I-03 [1.61 µm; red]. At these wavelengths, water is not very reflective (it absorbs more than it reflects). So, with low reflectivity in all three channels, water appears nearly black. That allows one to identify water easily. Here’s a Natural Color image from a clear day before the worst of the flooding began (2 June 2014):

VIIRS "Natural Color" image, taken 17:28 UTC 2 June 2014

VIIRS "Natural Color" image, taken 17:28 UTC 2 June 2014

That’s Paraguay in the center of the image. Rio Paraguay is the north-south river that cuts Paraguay in half (OK, maybe 60-40). Rio Paraná is the big river that marks the eastern border between Paraguay and Argentina, and turns south after acquiring Rio Paraguay’s water. (Look for the big reservoir in the upper-right, and follow that river down to the bottom of the image, left of center.) Make sure you click on the image, then on the “3298 x 2345″ link below the banner to see the full resolution version. Compare that with a similar image from the only clear day at the end of the month (30 June 2014):

VIIRS "Natural Color" image, taken 17:03 UTC 30 June 2014

VIIRS "Natural Color" image, taken 17:03 UTC 30 June 2014

At first glance, the most obvious flooding occurred along the Paraná in Argentina. But flooding is noticeable along the Rio Paraguay if we zoom in for a closer look. Here’s a “before” (2 June) and “after” (30 June) overlay for the area around Paraguay’s capital city, Asunción:

Drag the vertical bar over the images from left to right to compare the two. (If this “before/after” trick doesn’t work for you, try refreshing the page. It may not work at all if you’re using Google Chrome.) The flooding you see here near Asunción was associated with only a 2 m (6 ft) water rise.

Something interesting happens when we focus in on the Paraná at the Itaipú Reservoir, just upstream from Rio Iguazú:

VIIRS "Natural Color" images of Itaipu Reservoir, June 2014

VIIRS "Natural Color" images of Itaipu Reservoir, June 2014. These images have been brightened to highlight difference in reservoir color.

After the flooding, the reservoir no longer appears black. This is because the flooding washed an awful lot of dirt into the water. And it really shows up in the “True Color” RGB composite:

VIIRS "True Color" images of Itaipu Reservoir, June 2014

VIIRS "True Color" images of Itaipu Reservoir, June 2014.

The water appears more turquoise before the flood, and brown after the flood. This is because the True Color composite represents the true color of the objects in the image. It is made from channels in the blue [0.48 µm; M-3], green [0.55 µm; M-4] and red [0.67 µm; M-5] portions of the visible spectrum. Take a look again at the Iguazú Falls video above and notice how brown the water is. The True Color images capture this. The reason the water appears blue and not black in the Natural Color composite is that there is enough sediment in the water to make it reflective at 0.64 µm (the blue component of the image). The longer wavelengths in the green and red components are not sensitive to the sediment, whereas the shorter wavelengths in the True Color components are very sensitive to sediment. (This is the basis for Ocean Color retrievals.)

If we focus in on the Rio Paraná near where it meets the Rio Paraguay, we can see clearly that the Natural Color highlights where the flood waters are, and the True Color highlights the sediment in that water:

VIIRS Natural Color and True Color images of the Rio Parana, June 2014

VIIRS Natural Color and True Color images of the Rio Parana, June 2014

Unfortunately, floods on the Paraguay and Paraná rivers are not uncommon, as a resident of Asunción explains:

BONUS: The NOAA/STAR JPSS group has put together a website on the flooding in Paraguay that features my Natural Color images along with a number of other VIIRS-based products that are being developed for flood detection. A lot of people from a number of different research groups played a part in this!

Sehr Schweres Unwetter in NRW

Not having full command of the German language, “sehr schweres Unwetter” seems like an understatement. It translates as “very bad thunderstorm,” which in this case is like calling the Titanic a “very big boat”. Of course, if you live in the Great Plains, you probably refer to a supercell thunderstorm as “a little bit of rain and wind” but the storms that hit Nordrhein-Westfalen (NRW) on 9-10 June 2014 rival anything the toughest Oklahoman has experienced (minus the tornadoes). Also, keep in mind that Germany and the Low Countries have nowhere near the wide-open spaces the U.S. Great Plains are known for. Take 5 times the population of Oklahoma and cram them into a land area the size of Maryland. (Or, if you’re from Maryland, multiply your state’s population by three to approximate the population density of the area we’re talking about. Then ponder how anyone in that part of Germany is able to spend less than 18 hours per day stuck in traffic like you would be if you were suddenly surrounded by three times as many people.)

Let me set the scene for you. (If you’ve ever lived in the Midwest, you know the drill.) The air is hot and unbelievably humid. The sky is overcast. There is no wind to speak of, but there is a certain “electricity” in the air that tells you that a violent end to the heatwave is coming. Off in the distance, clouds lower and darken. A gentle rumbling of thunder slowly builds as the storm approaches. Lightning appears and becomes ever more frequent. Right before the storm hits, the winds pick up out of nowhere and… Wait! I don’t need to describe it. I can show it to you:

http://www.youtube.com/watch?v=TFbsubhW5s0

http://www.youtube.com/watch?v=9sLfWkqoIq8

EDIT: I did need to describe it, because the videos are no longer available. If you weren’t able to see the videos before they were removed, they showed scary looking clouds and nearly constant lightning approaching Bochum. In fact, there were an estimated 113,000 lightning strikes across Germany from the storm.

Germany is, apparently, a land of iPhones and GoPros and all sorts of video recording equipment, and there is no shortage of video of the storm. There are videos of the storm approaching from different perspectives (here, here and here), the strong winds and heavy rains that are more reminiscent of a tropical storm (here, here and here), footage of the lightning in slow-motion and, because this is the Internet, a 30 min. montage of storm footage set to salsa music (although one commenter says the first footage is from a storm in 2010).

The aftermath is pretty impressive also – trees and large branches down everywhere blocking roads, crushing cars and stopping the never-late German train system. In fact, 6 people were killed – mostly by falling trees. Winds were observed in the 140-150 km h-1 range (approximately 85-90 miles per hour), which puts it just below a Category 2 hurricane according to the Saffir-Simpson scale. There were even reports of baseball sized hail, something that’s not unusual in Oklahoma, but is very rare in Europe. (Here is some pretty big hail in the town of Zülpich from earlier in the day.)

Now that you’ve used up the last 90 minutes looking at YouTube videos, let’s get down to business. What do satellites tell us about this storm?

EUMETSAT put together this animation of images from the geostationary satellite Meteosat-10:

Watch that video again, preferably in fullscreen mode. First, the white boxes highlight the supercell thunderstorms over Europe between 01:00 UTC 9 June 2014 and 08:15 UTC 10 June 2014. Right before sunset on 9 June, you can see a storm moving north out of France into Belgium that seems to explode as it heads towards the Netherlands and western Germany. This is our “schweres Unwetter”. The second thing to notice is where that storm is at 02:00 UTC on the 10th. That was the time that VIIRS passed overhead.

So, without any more bloviating, here’s the high-resolution infrared (I-5) image from VIIRS:

VIIRS I-5 image from 02:07 UTC 10 June 2014

VIIRS I-5 image of severe thunderstorms over Europe from 02:07 UTC 10 June 2014

The storm that caused all the damage over Nordrhein-Westfalen has weakened and is now over northeastern Germany on its way to Poland. But, a second impressive supercell complex is pounding Belgium and the Netherlands, and taking aim at western Germany once again.

The coldest pixels are 196.5 K (-76.7 °C or -106 °F) in the storm over Benelux and 198.7 K (-74.5 °C or -102.1 °F) in the storm over northeast Germany. Another impressive thing about these storms is their size relative to the size of these countries. That Benelux storm looks like it’s at least five times the size of Luxembourg and as big as Belgium! (And I’m not counting the area of the anvil, which is even larger. I’m only counting the area containing overshooting tops.)

Since it’s nighttime, what did the Day/Night Band see? Well, the answer depends on how you display the data. You see, we’re approaching the Summer Solstice in the Northern Hemisphere, where the days are long and twilight encroaches the nighttime overpasses at these latitudes. If you try to scale the radiances from lowest = black to highest = white, you get something like this:

VIIRS Day/Night Band image, taken 02:07 UTC 10 June 2014

VIIRS Day/Night Band image, taken 02:07 UTC 10 June 2014. Radiance values are displayed and scaled according to text above.

That’s not very helpful because the radiance values vary by 6 orders of magnitude across the scene and we only have 256 colors to work with to relay that information. But, we can take advantage of the fact that the Day/Night Band radiance values are, to the first order, a function of the solar and lunar zenith angles, and use this as the basis for a “dynamic scaling” that compares the observed radiance with an expected maximum and minimum radiance value that is a function of those angles. (In case you’re interested, the dynamic scaling algorithm used here is based around the error function.) This allows you to produce something like this:

VIIRS Day/Night Band image, taken 02:07 UTC 10 June 2014

VIIRS Day/Night Band image, taken 02:07 UTC 10 June 2014. This image uses dynamic scaling as described in the text.

Here, we’ve lost some quantitative information (colors no longer represent specific radiance values) but we’ve gained valuable qualitative information.  Now we can see where the storms are! Notice the shadows in the overshooting tops of our Benelux storm – right where the coldest pixels are in the infrared image. We can see some of the city lights, but not others, because the twilight encroaching from the northeast is brighter than the cities in that part of the image. (It is easy to pick out London and Paris, though.) If you read the previous post, you might be wondering why there are no mesospheric waves with these storms. That’s because there is too much twilight (and moonlight) to see the airglow. (There’s also the possibility that the stratosphere and mesosphere weren’t conducive for vertically propagating waves, but you wouldn’t be able to tell that under these lighting conditions.)

Some people like to combine the infrared with the Day/Night Band into a single image. This is done by changing the opacity of one of the images and overlaying it on the other. Here’s an example of what that looks like using the dynamically scaled Day/Night Band image:

VIIRS combined IR/DNB image from 02:07 UTC 10 June 2014

VIIRS combined IR/DNB image from 02:07 UTC 10 June 2014

The light/shadow effect of the visible information adds a sort-of 3-D effect to the infrared images and, since this is the Day/Night Band, it can show where the storms are in relation to the urban areas. Here, it seems to work better for the Benelux storm than it does for the other one. (Of course, it would be better without the twilight. And, it works best with a full moon, which occurred three days later.)

Of course, if you have access to the Near Constant Contrast imagery, you don’t have to worry about scaling. The imagery is useful as-is:

VIIRS NCC image, taken at 02:07 UTC 10 June 2014

VIIRS NCC image, taken at 02:07 UTC 10 June 2014

And the combined IR/NCC image looks like this:

Combined IR/NCC image from 02:07 UTC 10 June 2014

Combined IR/NCC image from 02:07 UTC 10 June 2014

In case you’re interested, there are additional videos, animations and images of these storms from the Meteosat High Resolution Visible (HRV) channel at the EUMETSAT Image Library.