Some of those cool Sept 21 images are increasing my anticipation of the T72 flyby (due to happen in about 17 hrs)!
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Some T72 Titan flyby raw images have come down! Nice outbound views of Adiri taken by the WAC. An example, W0065713 (blended with the SSS image at same distance) appears below.
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Cool image.

I wonder if the vaguely meteor-looking streak in this image (from here) is just a data dropout or might be something more interesting? Other images have what looks like dropouts, so it probably is...

Cosmic ray hit on the CCD.

Yeah, data dropouts are always aligned horizontally and usually black, not bright.

Ah, thanks.

Outbound WAC view of Adiri (W00065688) maps well onto the SSS Titan view from Cassini at 42K km. (HLS is approx location of Huygen's landing site)

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This seems interesting
http://saturn.jpl.nasa.gov/photos/raw/rawi...?imageID=228405
http://saturn.jpl.nasa.gov/photos/raw/rawi...?imageID=228413
http://saturn.jpl.nasa.gov/photos/raw/rawi...?imageID=228412

That's some weird-looking cloud!

That's putting it mildly!

Stack of 3 CB3 frames:
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Could we be looking at an eruption or even impact event here??? A CB2 frame later shows the formation to pretty much show no evolution, except a slight hint of change in the "upward" cloud tongue, but probably due to raw jpeg compression, lower atmospheric transparency and 1/2 resolution.

Looks like another big equatorial storm cloud over Senkyo!
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As the winds are supposed to be eastwards through most of the troposphere, these cloud streaks seem to be converging, not diverging, which doesn't make much sense to me.

edit- the range of latitudes covered by these streaks is also very abnormal. The two outer streaks are almost (well...) in north-south direction!

The center of the cloud is located over S Senkyo, very near where there is an strangely interesting dark splot in the ISS [-23 S, 335 W].

I'm just sayin'....

Whatever it is, it appears to be well inside the haze as it's only visible in longer wavelength filters. There were other cloud outbursts that were visible in the red filter so from that standpoint it's not entirely unusual. It's the shape of the cloud that has me completely baffled.

Good thing Saturn is entering conjunction now...

A not particularly good RGB combo where it's also detectable:
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Notice the cloud is centered near the global dark band edge. Could the circulation pattern in different "hemispheres" explain for multiple streaks, one carrying stuff to the north and other to the south? Notice also that there are hints (CB3 frames) of two small clouds east of this one, both have the more "normal" E-W streakish appearance.

... but then the flow would have to be westward! Might be some strange instability or something, but I'm a bit surprised by it.

-edit: I guess the higher latitudes could have slower velocities than the equator somehow.

It seems to be tropospheric only indeed. Some faint patch at high latitudes in the stratosphere (MT2 and MT3), but probably unrelated I would think.

?Could this be the early propagation of Rossby waves that may have produced clouds at different latitudes in the April 2008 S. Belet storm imaged by Gemini N by Shaller, Roe and Brown?

mmm perhaps a bit like the v-shaped markings on Venus

The zonal atmospheric flow pattern may be different at this time of the equinox. According to Friedson et al http://www.sciencedirect.com/science?_ob=M...=/sdarticle.pdf atmospheric flow rises at low latitudes, flows towards the poles and descends at higher latitudes. Could we be seeing this pattern in the clouds?

Here's a ratio image of a stack of flatfielded and unsharped CB3 frames and an MT1 frame to roughly remove the effects of illumination.
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Thanks Gordan. I had suspected that there were two small thin clouds near the arrowhead shaped bright terrain at center left. This image seems to confirm that.

Dunno if they are associated with the main "cloud feature" or not.

It would be interesting to see that reprojected to simulate the view from directly above.

It would be incredibly distorted being so close to the edge.

A reprojected view so close to the limb would only be accurate if the cloud feature was very close to the ground. I'm not entirely sure that's a safe assumption to make.

Edit: snap! beat me to the punch.

Agreed, differences in elevation could distort the result. I only proposed the idea because previous posts suggest it's confined to the troposphere, i.e. no higher than 40 km or so, and because it's clearly so large in horizontal extent. Also, if it's the spreading top of a giant convection cell or cluster thereof I think there's a good chance that the upper surface of the cloud is reasonably level. I still hope somebody has a go at the reprojection. It would at least facilitate comparison with Earth-based observations of previous events missed by Cassini.

Some further thoughts - -

All previous cloud patches observed by Cassini have been groupings of latitudinal streaks, but this one at first sight doesn't look like that. It may be that this cloud patch is the same, but the circumstances of viewing make it look different, or it may really be different. Let's suppose the latter. What could account for this?

Perhaps we are seeing different stages of the same phenomenon. The cloud forms in some random and sudden way in which no particular direction is favoured, leaving an 'ink blot' which is then sliced into latidudinal streaks during calmer times. This one is just fresher than the others observed so far. . . .

???

The extent of this cloud and its shape seems unique compared to what we've seen from Cassini's cameras so far. Still it may be very similar to the event of April 2008 where tropical storm clouds were documented via ground based observatories (NASA infrared telescope facility initially). It would be interesting to learn if this event is right now under observation from the Gemini North observatory!!
The animation below depicts the extent of the cloud on the Titan planetary grid.
??? have all the Sept 27 raw images come down ?

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I know a bunch of hard core planetary climate scientists have seen these images and are going wow!!! I think they could post their gut responses without jeopardizing their Science or Nature articles...

Wow!

Craig

Indeed!

Gonna be fascinating to hear the pros' take on this thing. By any chance, were any ground-based observatories taking albedo measurements of Titan shortly before T72? Would be useful to constrain how much time this feature had to develop.

Yup. They noticed. cpcomments e-mail went out 8:30 PM today from Carolyn Porco. From message:

"Just down on the ground today: Images of some of the largest clouds our
cameras on Cassini have yet seen on Titan! And the fact that we see
them in the equatorial region is big news and may signify seasonal
change is underway!"

http://www.ciclops.org/view_event/142/TITA...138_RAW_PREVIEW

We had good views of Senkyo from the 13 of September and there were no obvious clouds at that time.
Still, plenty of time for something to develop after that however.

Mike Brown posted this on twitter:

Zonal (so, west-east) wind speeds tend to be a lot higher than any vertical motion. But the change in circulation is probably the reason why there are now more clouds at the equator (or clouds at all!).

As far as vague predictions go...
http://www.unmannedspaceflight.com/index.p...amp;#entry89833

Umm... yeah.

Let's be honest, we knew from HST that huge equatorial storms form during equinox as far back as well the last equinox in 1995. Not exactly a bold statement to say that weather can change on a seasonal basis...

VP: that's what I thought, but apparently not equatorial
http://www.unmannedspaceflight.com/index.p...st&p=144705

This is frustrating: No matter how hard I try to interpret this, I'm certain that I have it wrong:(

In what direction are the dunes running, relative to the cloud? Aren't the ridges running withn ~10 deg as the same direction as the arrow?

Titan with the spectacular T72 S Senkyo cloud were photographed nearly simultaneously through spectral bandpass filter combinations on Sept 27. The CB3 CL1 filter combo provided striking cloud and surface detail at 938 nm http://saturn.jpl.nasa.gov/photos/raw/rawi...?imageID=228405
whereas photos through the MT3 CL1 filter showed no surface and only a hint of the cloud but emphasized the NS hemispheric asymmetry of the lower stratospheric haze. http://saturn.jpl.nasa.gov/photos/raw/rawi...?imageID=228415
The stratospheric haze, detached haze layer and dark N polar hood were prominent in the CL1 UV3 image http://saturn.jpl.nasa.gov/photos/raw/rawi...?imageID=228408
Difference Blending CL1 CB3 and CL1 MT3 filtered images in Photoshop produced some interesting results however! (see below). This blending mode emphasizes color pixel brightness differences between overlaid images producing a darkening of blended pixel areas where the 2 images differ. Adjusting the opacity of the blend to 50% produces interesting effects in the T72 cloud showing preservation of the central portion (yellow arrow) but disappearence of the N>S arms of the cloud (small white arrows, 3rd image in the animation). This attenuation is most prominent at higher latitudes beginning just to the North of the NS hemisphereic asymmetry. Increasing the opacity of the difference blend to 90% reveals much of the cloud (excepting the central portion) as a dark area (last image in the animated sequence below).
The graphic on the right shows the difference blend of a CB3 and UV3 image compared to the CB3 MT3 image at 50% opacity suggesting the entire cloud is well below the level of stratospheric haze level seen through the UV3 filter but only the NS arms of the cloud are below the deeper atmospheric level reached with the MT3 filter.
Making several assumptions, one layman’s interpretation of these observations suggests the ends of the NS arms of the cloud are descending to a lower height in the troposphere as they move to increasing latitudes away from the center of the cloud and are not a uniform flat cloud top. This effect is more pronounced to the North of the zonal hemispheric asymmetry (as suggested in Ugordan's post #13 as well). Perhaps this pattern supports the theoretical pattern of equinox atmospheric flow mentioned in the article of post #17 in this thread.
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I think that this is largest non-polar cloud photographed by Cassini to date. It's really massive.

That's why they used those badass filter combinations. Oh wait. bandpass

There was also this detection of large equatorial storms one year ago: Storms in the tropics of Titan
full PDF here

Yes a remarkable storm! Actually was 2 yrs ago in April 2008. See also http://www.unmannedspaceflight.com/index.php?showtopic=6146.

Here's a distorted, cartoonish attempt at reprojection of the T72 storm to simulate the view from above. At least it lives up to its nickname of the 'arrow-shaped' storm !
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Thanks for doing that! I never get tired of asking favours here.

T72 storm cloud details using enhancement of the raw images with Photoshop. Originals rotated 205 deg left. The top of cloud appears to have layered structure in (a) CL1 CB3 and a difference blend of that with the CL1 CB1 image shows interesting differences (d) that when magnified (e) look similar to the clusters of cloud tops imaged in 2004 by Cassini (f) see http://ciclops.org/media/sp/2009/5480_12560_0.pdf

While these could be artifacts of processing, clusters of individual storms are predicted in models of Titan methane cloud formations that grow to produce intense precipitation. http://www.nature.com/nature/journal/v442/...ature04933.html

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With the stretched T72 storm image map above and VP’s enhanced ISS basemap and SAR swaths one can approximate where the most intense portion of the storm was located and where evidence of localized flooding might be sought. The mid portion of the T50 swath and just south of SENKYO might be good places to revisit to look for changes either with SAR or the WAC or NAC. With Cassini in safe mode and imaging for T73 not likely this may have to wait for some time.
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More haze, this time it's the south pole



Calibrated PDS data, wide-angle RGB view taken 2010-09-24 from a distance of 23 thousand km and at a phase angle of 120 degrees.

Nice! It's nice to see the haze now also accumulating more at the South.

I don't know if "accumulating" is the right word, but it *definitely* looks different than it used to. Here's a similar view from August 2005, from 27 000 km and 115 deg phase angle:

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Fascinating to watch the slow march of the seasons on Titan.