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Juno perijove 5, March 27, 2017
Bjorn Jonsson
post Apr 3 2017, 12:10 AM
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QUOTE (Gerald @ Apr 2 2017, 08:51 AM) *
For completeness, here the statistics resulting from the calibration run:

Have you checked how accurate the interframe delay in the metadata is? For the PJ5 images it is 0.371 but I'm starting to suspect that I might get slightly better results by adjusting it slightly. I haven't tried it yet though but I'm pretty sure any adjustment (if needed) is less than 0.001.

QUOTE (Gerald @ Mar 31 2017, 11:45 PM) *
Is it possible to discern any rotation in these large storms within the five and a half minutes between images #109 and #110?
My best candidate is the large white (anticyclonic) oval A6:

Quick back of the envelope calculations seem to suggest this *might* be possible. The elapsed time between the images is ~330 seconds. Assuming a wind speed of ~60 m/s near the A6 spot's periphery (a very crude but probably not bad assumption made by scaling down the speed in the bigger white oval BC in the Voyager era by a factor of ~2 since A6 is smaller) results in a ~20 km movement. This corresponds to roughly 2-3 pixels in the higher-res image which is noticeable if the images are well aligned.

QUOTE (scalbers @ Apr 2 2017, 07:33 PM) *
That has some super detail in it, including what look like convective cloud elements. Do we know what the pixel resolution is? Considering the context, these convective clouds on the right are in a zone, with overall low altitude clouds, so that we see more into a water rich level. The redder clouds on the left are in a higher belt. It seems the bluer nature of the zone would be consistent with looking through some overlying clear air with attendant Rayleigh scattering.

Hmmm... but I have always been under the impression that the whitish zones are higher in the atmosphere than the darker and more reddish/brownish belts and that they are probably ammonia cirrus (the water clouds are much lower in the atmosphere and look darker and more fuzzy). But the possible convective clouds in Roman's image are very interesting. An interesting fact is that these small, whitish clouds are very common and not just in Roman's image. They occur both as isolated features, e.g. at ~(435,740) and in 'clusters', e.g. at ~(980,105) in Roman's image above. And there's a lot of them in the whitish zone. Some of them look like cumulus to me. These clouds seem to occur at various locations although some areas are more likely to have them than others.

There are also small/narrow 'elongated', whitish clouds at various locations, typically above darker clouds. I suspect their altitude is similar to the convective/cumulus clouds. Here is an example, an enhanced crop from an image (PJ5 image 110) I'm working on:

Attached Image
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mcaplinger
post Apr 3 2017, 12:38 AM
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QUOTE (Bjorn Jonsson @ Apr 2 2017, 04:10 PM) *
Have you checked how accurate the interframe delay in the metadata is? For the PJ5 images it is 0.371...

The metadata value is 1 millisecond too small (there was an off-by-one misunderstanding about how the hardware interpreted the commanded interframe value.) Otherwise it's under the control of a fairly stable crystal oscillator but there could be some drift on order of 10-20 PPM over temperature.

The spacecraft spin rate is usually not precisely 2.000 RPM so that's probably a bigger unknown.


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Disclaimer: This post is based on public information only. Any opinions are my own.
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scalbers
post Apr 3 2017, 12:45 AM
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QUOTE (Bjorn Jonsson @ Apr 3 2017, 12:10 AM) *
Hmmm... but I have always been under the impression that the whitish zones are higher in the atmosphere than the darker and more reddish/brownish belts and that they are probably ammonia cirrus (the water clouds are much lower in the atmosphere and look darker and more fuzzy). But the possible convective clouds in Roman's image are very interesting. An interesting fact is that these small, whitish clouds are very common and not just in Roman's image. They occur both as isolated features, e.g. at ~(435,740) and in 'clusters', e.g. at ~(980,105) in Roman's image above. And there's a lot of them in the whitish zone. Some of them look like cumulus to me. These clouds seem to occur at various locations although some areas are more likely to have them than others.

Attached Image

Thanks Bjorn for the correction/clarification. I was somewhat influenced by the appearance of the image where it seemed like some of the belt clouds were running on top of the zone clouds at the border - perhaps an illusion. I will suggest that the zones would have a mix of elevation as I believe IR hot-spots (bluish in visible) tend to occur in the zones and we may be seeing some of these on a small scale in this closeup. These hot-spots are areas with very few (or very low) clouds. It would be interesting to look at closeup IR data or something like that to tell the relative altitude of the convective cloud bottoms and tops relative to the more stratiform white (ammonia) clouds. Maybe stereo images can help on this as well.

Within the belts, are the white spots higher or lower than the surrounding reddish clouds?


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Bjorn Jonsson
post Apr 3 2017, 12:51 AM
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QUOTE (scalbers @ Apr 3 2017, 12:45 AM) *
Maybe stereo images can help on this as well.

I think it might be possible to use images 109 and 110 as a stereo pair. I haven't tried it yet but probably will.
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scalbers
post Apr 3 2017, 01:00 AM
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This is a good learning experience for me. If we look at this hi-res IR/visible pair we can see most of the hot spots are in the brown belts as you suggest. However some bluish areas continue into the zones with "suppressed" IR warmings. This suggests to me the bluish areas in the zones are areas fairly cold in IR with thin high ammonia haze, while also allowing us a partially transparent view with scattered visible light into much lower altitudes.

http://www.dailymail.co.uk/sciencetech/art...approaches.html (scroll down page to see image pair and look just right of center in the images)

Areas that are dark within the belts look to be the hottest of all, perhaps no clouds are present at all in these locations.

Will be interesting if we can see some simultaneous images of the VLT IR data and Juno. The link is showing images from the ESO VLT and ground-based visible light images as a dry run for the Juno observing campaign.

A similar situation occurs with satellite images of Earth with thin cirrus clouds. The IR signature looks cold while in the visible it can be relatively dark (blue in color) with the ground still evident.


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jccwrt
post Apr 3 2017, 03:55 AM
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QUOTE (Bjorn Jonsson @ Apr 2 2017, 06:10 PM) *
Hmmm... but I have always been under the impression that the whitish zones are higher in the atmosphere than the darker and more reddish/brownish belts and that they are probably ammonia cirrus (the water clouds are much lower in the atmosphere and look darker and more fuzzy). But the possible convective clouds in Roman's image are very interesting. An interesting fact is that these small, whitish clouds are very common and not just in Roman's image. They occur both as isolated features, e.g. at ~(435,740) and in 'clusters', e.g. at ~(980,105) in Roman's image above. And there's a lot of them in the whitish zone. Some of them look like cumulus to me. These clouds seem to occur at various locations although some areas are more likely to have them than others.


It's possible that the white spots are a form of pileus in the ammonia cirrus deck or perhaps even overshooting tops of water vapor cumulus. Given some of the Voyager images you found in a similar region last year, I'm inclined to say it's the latter, but I don't know enough about Jovian meteorology to say if a water vapor-driven updraft is capable of rising that high through the cloud deck without collapsing.

QUOTE (scalbers @ Apr 2 2017, 07:00 PM) *
This is a good learning experience for me. If we look at this hi-res IR/visible pair we can see most of the hot spots are in the brown belts as you suggest. However some bluish areas continue into the zones with "suppressed" IR warmings. This suggests to me the bluish areas in the zones are areas fairly cold in IR with thin high ammonia haze, while also allowing us a partially transparent view with visible light into much lower altitudes.


The equatorward side of the equatorial belts is marked by a vertical jet stream oscillation. You get an IR hotspots where the jet stream is descending and warming the air through adiabatic heating. That clears out the upper cloud decks to give us an unobstructed view deep into Jupiter (probably down to the water cloud layer), which correspond with the dark blue areas in the VIS along the edge of the belt. The ascending portion oscillation generates a long-lived convective updraft that encourages the formation of ammonia cirrus muddied with some of the ammonium sulfate cloud layer that's been carried upwards. Most of that cirrus drifts equatorwards, but some of it gets entrained within the belt circulation patterns and is forming an IR-blocking layer that shows up against the bright IR radiation emitted from the belts. The belts are also a region of generally descending air, so you might also be getting variable IR bright spots where the ammonium sulfate clouds are being eroded more deeply by adiabatic heating.
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scalbers
post Apr 3 2017, 04:40 PM
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We can see these variable hot-spots in the belts as I'm here reproducing one of the images from the link in post #35. The IR blocking areas in the belts appear to be where white clouds are mixing with the red ones. However the white clouds in the belts appear different in nature/structure than the white clouds in the zones (in #109), so it's unclear to me whether entrainment from the zones is really going on.

Attached Image


The convective clouds in #109 are mostly in a zone, so I wonder if the visible cumuliform cloud is all an overshooting top, or if we can see (through the cirrus) deeper to the source region of the water vapor. It also seems like the rising motion in the zones would be dynamically forced on the large scale with the convection happening more on the small scales. I would continue to entertain the notion that in the zones we're seeing a combination of thin white high ammonia haze, with more structured denser white clouds at a lower altitude. This possibly explains why we see structure in the visible and not so much in the IR. The convection could be happening between these two levels. Some of the darker areas in the zones (and belts) would be where we are seeing even deeper.

This link is actually suggesting that the zones have large scale descent. Though it's interesting that they say most convective elements are in the belts. Maybe that's true of some larger storms that could be seen in the Cassini flyby in 2000, or the embedded convective elements in the whiter clouds within the belts as in Bjorn's image in post #31. Perhaps looking at Juno's images now is giving some fresh perspectives on all this. Possibly larger convective storms tend to be in the belts and smaller ones in the zones.

On another note I can see rotation in Gerald's oval A6.


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Bjorn Jonsson
post Apr 3 2017, 08:17 PM
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Here's everything from image 110 ("String of Pearls" plus more) processed from the raw framelets. First an approximately true color/contrast version (small scale features have been sharpened a bit, partially simply to compensate for all of the resampling steps during processing):

Attached Image

Attached Image
Attached Image


And then a version of these images where the effects of global illumination have been removed and the contrast, color saturation and sharpness exaggerated:

Attached Image
Attached Image
Attached Image


Most/all of the features here are also visible in image 109 posted earlier by Roman but the resolution of that image is higher. As mentioned earlier it might be possible to use images 109 and 110 as a stereo pair.

Juno's altitude was ~20,000 km when the image 110 framelets were obtained. The processing is more or less identical to what I did when I processed a PJ-4 image some time ago.

These images reveal lots of interesting features, some of which are relevant within the context of the interesting Jovian weather/clouds discussion above. "String of pearls" oval A6 is visible. I find the circular storm SSW of oval A6 particularly interesting. Cloud shadows are visible within it and elongated, elevated clouds within the storm apparently form a spiral.
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Gerald
post Apr 4 2017, 12:00 PM
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Outstanding work, Björn!
I didn't yet include full illumination adjustment into my renditions, but am curious how those results will eventually compare to yours. One to three CPU cores are running almost around the clock. So, it will take another few days, before I've completed all "straightforward" products, and find time to dig a little deeper into the data.

I've tried the 109 / 110 pair as stereo, and am not yet quite sure, whether a 3D effect is perceptible. There is also some risk to confuse cloud motion with parallax.

Here some of my "straightforward" products:
PJ05 Approach Movie (and cropped close-ups), level 1, decompanded stills. All images rendered with the same set of parameters (best for distant images), therefore some of them may not be perfectly rgb aligned.
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stevesliva
post Apr 4 2017, 01:06 PM
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Some quite nice crescent/quarter shots in your stills, Gerald!
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scalbers
post Apr 4 2017, 05:21 PM
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QUOTE (Gerald @ Apr 4 2017, 12:00 PM) *
I've tried the 109 / 110 pair as stereo, and am not yet quite sure, whether a 3D effect is perceptible. There is also some risk to confuse cloud motion with parallax.

The blinking animation Gerald posted earlier was useful to look at in the context of seeing things in 3D (as a complement to an anaglyph or side-by-side pair). I think it could show some parallax if it is registered more closely. I suppose the risks would be mainly the cloud motion in a rotating spot, or some type of vertical wind shear in a jet region. Other more uniform movements could be compensated for.


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Gerald
post Apr 5 2017, 05:24 PM
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Departure sequence, level 1 stills, decompanded, some overlap with approach sequence, but slightly different parameter settings.

Most of PJ05 "straightforward" processing completed. Time to work on enhancements, movies, advanced data reduction software, may be another attempt to create stereo products.
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Jerry
post Apr 14 2017, 03:49 AM
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Attached Image


What is the circular cloud formation in this image? Is it just an artifact of processing, or is it something real?

Thanks.
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Bjorn Jonsson
post Apr 14 2017, 12:20 PM
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This is definitely a real feature, it appears in more than one of the source images (framelets) used to make the final image.
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Jerry
post Apr 14 2017, 09:54 PM
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QUOTE (Bjorn Jonsson @ Apr 14 2017, 07:20 AM) *
This is definitely a real feature, it appears in more than one of the source images (framelets) used to make the final image.


I don't know if it's possible in a gas medium, but it almost looks like a complex crater.
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