5/3/2005: Korea at night

[Karenv]

"IOW I don't understand your point."

The difference between the original picture submitted by UT and the pics with some light could be due to time of day and just having dim lighting. Why assume that it is doctored when there are simpler explanations?

[xoxoxoBruce]

Good show, UT. That one shows the islands between SK and the Japs and explains those lights.

[tw]

Originally Posted by Karenv

"IOW I don't understand your point."

The difference between the original picture submitted by UT and the pics with some light could be due to time of day and just having dim lighting. Why assume that it is doctored when there are simpler explanations?

So why are lights in the Korea Straits off in the water adjacent to the island of Tsushima? Why does the ocean have more lights than the adjacent island of Tsushima? Why are there lights as bright as in Seoul located at 36 degrees N, 130 degrees East in the East Sea (Sea of Japan) off the city of Pohang? No land mass (island) exists there. Why are there bright lights in the Yellow Sea off the city of Gimpo and Incheon (west of Seoul)? How does time of day cause bright lights to appear where only ocean should exist? I don't understand your point. What does time of day have to do with lights where no human civilization should exist?

Those lights don't appear in a picture provided by xoxoxoBruce and in a new photo provided by UT. So what created lights where no land masses exist? Time of day?

[russotto]

The lights in the water are boats.

[glatt]

Here's another image and an explanation of the lights in the water.

Take a look at Japan and South Korea, brightly lit up. Contrast the latter to North Korea, the border between the two being clearly demarked where the light stops at the 38th parallel. Do you see the light blue in the waters surrounding Japan and South Korea? This represents large floodlights employed by the fishing fleet at night, to draw squid and other sea creatures to the surface where they can easily be caught. This is the sign of fisheries on the brink of collapse. Similar lights can be seen off the coast of China and in a few other spots in the other images.

[tw]

Originally Posted by glatt

Here's another image and an explanation of the lights in the water.

The fishing fleets create lights greater than or equal to the light output in cities of millions? Look at North Korea where 5 megawatts is a significant electricity. Notice the little amount of light. Look at the South Korean cities where the electric consumption is thousands of megawatts.

What ships are lightning the ocean even with 5 megawatts? If the lit ocean areas were not so large (the size of P'yongyang in N Korea), then I might appreciate that explanation. But the numbers necessary to light up such large areas just cannot be accounted for by a fishing fleet. Its just too much electricity and in multiple ocean areas that are too large. One fishing fleet lights an ocean area the size of Seoul and its suburbs? If the generators on those boats are that large, then where do they store the day's catch?

Remember, I am questioning the validity of the first photo posted by UT. Those other photos don't show all those lights offshore. And those other photos show he islands in the Korea straights properly illuminated only on land- not in the Straits.

[glatt]

I'm not a fisherman, so I don't know.

Perhaps the light in these images is a measure of light and not electricity. Perhaps much of the light from these fishing boats is being reflected up into the sky, and that isn't happening as much on the land, where dark colored pavement, dirt and vegetation absorbs much of the light from street lights.

When you shine a light from a high angle into the water, some penetrates the water, and some bounces off the surface like a mirror. Perhaps these fishing boats are, in effect, aiming their lights down into the ocean at the same time they are aiming them up into the lenses of the cameras in the satellites.

[Undertoad]

Perhaps a high-contrast light, versus the blackness of sea, seems brighter on the image.

[xoxoxoBruce]

I would imagine the floodlights from the boats would be at a low angle, trying to light up as much surface area as they can. Lighting the surface of the water would show up in the pictures better than the equivalent city wattage that would only show incidental light escaping from where it's used.

This gave me a flashback of the search lights on trucks that use to mark supermarket openings and new car years at the dealers. They were gas powered and looking into the unit at a low angle it didn't look like those rows of little flames could produce that powerful beam that flashed the Batsign on the clouds.

[spanishguy]

I have spent probably too much of my time looking at satellite imagery from nasa. One thing that is certain is that the same location can look very different depending on a huge number of variables. This image did look a bit extreme based on other images I have seen. I took this one in to Photoshop and started playing with levels and correction. Here are some results.

<img src="http://home.cwru.edu/~tje2/korea-lights-analysis1.jpg">

I noticed there was a definite difference in the ocean brightness from left to right. pumping up the brightness and contrast brings this out more in the second image. The last image is 'corrected' by myself, eyeballing a line and trying to get the water to the same, consistent brightness. Pyongyang seems to show up much better and this image fits in more with others I have seen. Up in China, however, I think the lighting patterns are not so much cities as they are mountains or geographic features reflecting some sunlight.

<img src="http://home.cwru.edu/~tje2/obvious.jpg">

In the image above, I used the uncorrected version and only played with levels of brightness and contrast in order to really bring out the left-right differences in the image. It plainly shows that the image is not consistent from left to right, regardless of land mass or city lights.

<img src="http://home.cwru.edu/~tje2/contrasty.jpg">

This last image is a left-right corrected version in which I tried to get the lights to show up in a manner used in the other composites people are posting. It still is a bit inconsistent, and very grainy. It is closer to the other images, but quite frankly the image quality is too low and the overall calibration is too inconsistent to really make inferences about North Korea's light levels vs. levels in other parts of the image.

The popular Visible Earth composites are made from thousands of different images laced together. Average brightness for different areas are plotted from multiple observations. A single image is bound to contain inconsistencies, and should not be used directly without context. I'm sure the person who saw this and emailed it around just saw something that helped reinforce a preconceived notion about Korea's situation. Careful analysis shows that while there is a major difference, this image seems to exaggerate the light discrepancy.


There are other factors we haven't even touched - does North Korea use mostly sodium, metal halide, halogen, incandescent, or florescent lighting? At what wavelength is the picture taken? What time was it taken? Were there clouds? Snow? Dust storms? Was this a holiday in North or South Korea? Friday night football games? Tax day? Certainly, some of these are ridiculous questions, but taking a small number of pictures and making broad inferences is always dangerous. You ALWAYS will see things that seem to reinforce preconceived notions. Just ask Colin Powell.

[glatt]

Excellent post. Thanks for your perspective, and welcome to the Cellar.

[Catwoman]

Hola spanish guy.

[spanishguy]

Hi ya'll. A little info about the new guy: Just moved back to PA from Houston, TX. I'm not at all spanish or hispanic (fraternity nickname, long and boring story). I have 5 fingers (thumb inclusive) on my right hand. Many years ago, I was born, and I even have a certificate to prove it. I am not at all sarcastic.

BTW, the fact that the other images are composites is why fishing boats and other moving lights will not show up. The composites are designed to show 'permanent' lights, although degree of permanence is not really explained. Some of teh boats could actually be the islands themselves - don't think the blue coastlines are drawn perfect. South Korea's east coast buildup is probably not several miles inland, despite what the blue line shows. These pictures are often taken at odd oblique angles, and they don't always point north. Matching up a coastline drawing to a photograph is often difficult, and not always accurate. Islands usually don't quite line up - just use the blue lines for a general reference.

I still think much of the light in the Korea Strait is fishing boats, but the islands are not lined up very well.

[tw]

Originally Posted by Undertoad

Perhaps a high-contrast light, versus the blackness of sea, seems brighter on the image.

In IR pictures I had seen raw from the satellite, ground lights and clouds both appear. Those globs of 'light' in the oceans could just as easily been clouds. Notice a shortage of cloud cover in N Korea. Just another reason that the original picture posted by UT leaves me suspicious. Were clouds electronically removed in N Korea but not in S Korea or over the ocean? We have no way of knowing. We can only speculate. But it does look so. Cloud cover would explain those lights in the Korea Strait, Sea of Japan, etc.

Yes, IR from clouds does appear in night time images.

[BrianR]

http://www.fourmilab.ch/earthview/satellite.html

You get to choose which satellite you look from (no, no Keyhole sats) and the lat and long you look at.