High Altitude Hazes
By Candy on 2017-12-28 UT
Our first PJ1 images showed a high altitude cloud extending above the terminator. Other images show bands of haze.
Our first PJ1 images showed a high altitude cloud extending above the terminator. Other images show bands of haze.
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Attached is a more detailed description of how to find the limb in an image, how to rectify it, and how to get an idea about the structure of the hazes along the limb.
Here is our abstract for my talk given at the EPSC in Berlin in 2018 September, summarising the main patterns of haze bands in both hemispheres:
'Jupiter’s high-latitude hazes as mapped by JunoCam'
The subcomments of this comment will be used for a more complete survey of Jupiter's limb. The rectification algorithm is refined, and uses the mean brightness of the zone of the steepest brightness slope as a definition for limb.
Attached is a PJ12 survey. Considered are only close-up RGB images with the terminator outside the field of view.
Limb surveys for PJ12, PJ13, and PJ14.
Limb surveys for PJ09, PJ10, and PJ11.
Limb surveys for PJ15 and PJ16.
Limb surveys for PJ17 and PJ18.
Limb surveys for PJ01 to PJ08
Limb surveys for PJ19 to PJ23.
Note, that all PJ19 images are south polar outbound.
In PJ12, image #87, there is a section of a limb showing two layers of presumably detached haze. This might hint towards four stacked separate weather systems, three of which forming their own inversion layer. On Earth, inversion layers form when warm air is layered above cold air. For Jupiter, it's usually assumed, that temperature is decreasing with altitude. This assumption would suggest hazes of different chemical composition resublimating for specific temperature and pressure conditions, which gradually change with altitude.
A more complete survey of the Jupiter's limb during PJ14.
And here a survey of the first derivative (difference quotients) of the square-root encoded PJ14 limb profiles.
Here a crop of the brightness gradient, where a detached haze layer occurs.
The attached zip file shows an approach to analyse Jupiter's haze layer by observing the limb.
File
JNCE_2018197_14C00023_V01-raw_proc_hollow_sphere_c_pj_out.BMP_thumbnail_.jpg
is a draft processing of Perijove 14 image #23, JNCE_2018197_14C00023_V01.
The green lines in image file
JNCE_2018197_14C00023_mark_try17.png
show the automatically detected limb.
This limb is used for the limb rectification shown in image file
JNCE_2018197_14C00023_limb_try17.png
Along vertical sections of this rectified view, brightness values can be plotted into diagrams like indicated in file
JNCE_2018197_14C00023_limb_diagram_try17.png
The first derivative of the brightness plot shows the structure of the haze layer more distincly. This is shown in file
JNCE_2018197_14C00023_limb_diagram_derive_try17.png
The same method can be applied for each of the three color channels separately:
JNCE_2018197_14C00023_limb_diagram_deriveColor_try17.png
A large number of sections can be visualized by compiling the diagrams into a movie:
JNCE_2018197_14C00023_limb_diagram_deriveColorMov_try17.mp4
Note especially the time between 00:15 and 0:35, where there is forming a detached haze layer. But also continuous appearing haze can vary in its brightness gradient.
For an account of the hazes at PJ12, including a remarkable map of the northern hemisphere hazes seen at high phase angle, please see Part I of the report I've posted on the PJ12 thread.
--John Rogers.