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Juno perijove 8, September 1, 2017
scalbers
post Sep 24 2017, 12:00 AM
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Nice to see these realistically processed views. One fine point is that with such high resolution we might be able to resolve a region along the limb where a high clear portion of the atmosphere would produce a thin blue layer due to Rayleigh scattering. Is the limb fully shown in these images?


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Bjorn Jonsson
post Oct 1 2017, 12:43 PM
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The limb is not fully shown. The images are processed by creating a simple cylindrical map and then using the map to render an image. This 'truncates' the limb near the 1 bar level. That said, I suspect the resolution at the limb isn't higher in the JunoCam images than in many of the Voyager images since the resolution at the limb is much lower than at the nadir (I haven't computed the exact resolution at the limb though).

I have experimented a bit with creating JunoCam color composites showing the limb but the results aren't very interesting. The best processed Voyager image I know of showing the limb is this one from Voyager 1 and there is also a Voyager 2 mosaic. These are also probably the highest resolution color images showing blue sky at the limb that can be processed from the Voyager 1 and Voyager 2 data.
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Bjorn Jonsson
post Oct 6 2017, 07:51 PM
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Image PJ8_110, approximately true color/contrast:

Attached Image
Attached Image

Attached Image


And with enhanced color and contrast. The effects of the solar illumination have been removed:

Attached Image

Attached Image
Attached Image


Lots of cloud shadows are visible, especially in the 'central' image (the one where Jupiter's limb isn't visible). Possible vertical relief can also be seen at various locations.

And the relevant metadata:

IMAGE_TIME = 2017-09-01T21:37:50.343
MISSION_PHASE_NAME = PERIJOVE 8
PRODUCT_ID = JNCE_2017244_08C00110_V01
SPACECRAFT_ALTITUDE = 9838.0
SPACECRAFT_NAME = JUNO
SUB_SPACECRAFT_LATITUDE = 41.77
SUB_SPACECRAFT_LONGITUDE = 310.6919
TITLE = POI: AB Territory
Resolution at nadir: ~6.6 km/pixel
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Bjorn Jonsson
post Oct 7 2017, 08:28 PM
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The central image in the above post has some of the best examples of direct imaging of (probable) cloud elevation differences that I have seen in images of Jupiter. Here is an enlarged crop from the image with some annotations:

Attached Image


The sun illuminates the clouds from the west (left) in this image. Keeping this in mind it's looking very much like we are seeing 'topography' at various locations, in particular around the vortex left of center:

A: Clearly defined 'valleys'.
B: More subtle 'valleys' than in A.
C: Elevated and elongated high altitude 'walls' of clouds that are apparently roughly parallel to the wind direction around the vortex.
D: Elevated clouds that have a more irregular shape than the clouds in C.

There are also some some subtle indications that narrower and subtle 'valleys' and 'ridges' may spiral into the vortex toward its center.

It is possible that these features are due to clouds of different color/brightness and not due to altitude differences. However, looking at the image, altitude differences look to me like the obvious (and more likely) explanation.
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Bjorn Jonsson
post Oct 16 2017, 09:52 PM
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Image PJ8_124, true color/contrast version and an enhanced version:

Attached Image
Attached Image


In the enhanced version the effects of global illumination have been removed. This reveals various details in the dimly lit areas near the terminator and near the south pole.

And an orthographic view showing the south pole:

Attached Image


A latitude/longitude grid is included. This reveals the location of Jupiter's south pole. It's remarkable how different Jupiter's polar areas are from Saturn's. They look much more irregular and chaotic, the belt/zone structure breaks down and in particular there is no vortex centered on Jupiter's pole as in Saturn's case.

Another interesting feature is the relatively narrow, curved band of haze (?) not far from the pole.

A subset of the metadata associated with the original data:

IMAGE_TIME = 2017-09-01T22:34:02.788
MISSION_PHASE_NAME = PERIJOVE 8
PRODUCT_ID = JNCE_2017244_08C00124_V01
SPACECRAFT_ALTITUDE = 60546.9 km
SPACECRAFT_NAME = JUNO
SUB_SPACECRAFT_LATITUDE = -71.5392
SUB_SPACECRAFT_LONGITUDE = 355.0833
TITLE = POI: South Polar region
Resolution at nadir: ~40 km/pixel
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