[X] My Assistant

[ngunn]

Compare the predicted view in the latest 'looking ahead'

http://ciclops.org/view/5825/Rev_118

with the nothern hemisphere polar map:

Attached thumbnail(s)

 

[ngunn]

With reference to the Ciclops view I wonder if we'll be able to see if the four great 'Siberian rivers' at 9 0'clock (7 o'clock on the second image above) continue all the way to the polar seas?

[titanicrivers]

With reference to the Ciclops view I wonder if we'll be able to see if the four great 'Siberian rivers' at 9 0'clock (7 o'clock on the second image above) continue all the way to the polar seas?

Very neat images!!! Those curvilinear forms seem to gather ‘tributaries’ and head north. However they have been imaged (in T 30) at lower resolution SAR and do not appear very river like. (see image sequence below). Perhaps they are older valleys partially filled in with mid latitude atmospheric deposits; maybe some crustal tectonics produced them rather than running methane torrents. The channel of T 30 seemed to end long before the large lake coastline. Agree additional ISS imaging will be interesting nevertheless.

[titanicrivers]

T 21 also crosses some of the 'Siberean channels' and that SAR doesn't seem to give one the impression of fluvial carved channels either.

[ngunn]

Very neat images

Yes, but unlike yourself, Mike and others I don't make them but merely link back to them when relevant.

I agree, it's far too early to say what the 'Siberian rivers' actually are. I only give them that nickname because of their general appearance, scale and geographical location. On the evidence so far I would say they have probably been either formed or modified by liquid flow in a northerly direction, though not necessarily very recently. It will be fascinating to see if the new images confirm or alter this impression. If there is evidence of flow it will also be interesting to compare with the present regional gradient. A global elevation map of Titan was published recently - the one on wich Xanadu surprisingly turned out to be a depression. I'll try to find and post that link if nobody else does first. It would make an interesting additional layer on your excellent composites.

Ah - here's the paper:
https://www.sciencemag.org/cgi/content/abstract/324/5929/921
https://www.sciencemag.org/cgi/content/full/324/5929/921

EDIT :I don't have access to the full paper and can't find the Fig 3 elevation map anywhere, except in this tiny version -

Attached image(s)

 

[Juramike]

I don't think Titan has yet revealed the full diversity of river channels that are on it's surface. There could be a lot of really funky forms that we haven't seen yet.

Picture this: A large channel gets carved out, then becomes covered by insoluble, yet permeable, airfall deposits. A lower rainfall rate could allow subsurface flow the creeps aslong and keeps the channel deposits to remain wet (thus dark), but not be enough to clear out the channel.
(Terrestrial example: a small creek covered by snow. It still flows, it keeps the snow damp, but the channel is partially hidden.) Could this exist on Titan? Maybe.....

Or these could be cycloid cracks, or they could be curvy branching subparallel dark lines painted on just to torment us. (Just like the straight bright lines in Tseghi).

It'll be interesting to watch the story of the Siberian rivers develop as we get more data (ISS, VIMS, more RADAR, topoSAR, etc...)

[titanicrivers]

A global elevation map of Titan was published recently - the one on wich Xanadu surprisingly turned out to be a depression. I'll try to find and post that link if nobody else does first. It would make an interesting additional layer on your excellent composites.

An excellent suggestion! I was able to obtain the entire paper and although the paper tends to downplay correlation of surface features with the calculated regional elevations, (excepting the occurrence of lakes at the lower poles), the Titan ellipsoidal surface map does portray higher and lower regions that are of interest. For the "Siberian Rivers" region the surface suggest a higher to lower gradient concordant with the implied direction of flow of these channels as they roughly follow the course of the T30 SAR swath (see below).

[ngunn]

Looks like support for the possibility of flow at least. The elevation map projection though - doesn't it need 'unwrapping' into rectangular format before being overlaid on the ISS map?

[titanicrivers]

Looks like support for the possibility of flow at least. The elevation map projection though - doesn't it need 'unwrapping' into rectangular format before being overlaid on the ISS map?

Yes, the ellipsoidal map should have been expanded into a similar cylinidrical map as the ISS-SAR swaths map is; thanks for pointing that out.
In reviewing the paper again I found the straight altimetry data of the SAR swaths to be projected onto a cylindrical map format. This makes for neat composite and is a more accurate alignment of the data and is shown below. The elevation gradient support for northern flow of the 'Siberian Rivers' is still evident. Notable too is the Adiri 'high ground' and some higher elevation points in the area of possible VIMS mountains. (thats what I was trying to show with the Senkyo post!).

[ngunn]

Hey - that's brilliant, thanks!!

I see that the Adiri high is nicely placed to fit with catastrophic eastward flow at the Huygens landing site.

[titanicrivers]

I see that the Adiri high is nicely placed to fit with catastrophic eastward flow at the Huygens landing site.
[/quote]

Yes and take a look at the first part of T 39 swath below Adiri. This swath traces south poleward and the altimetry data (actually SAR monopulse radar mode data ) shows a several hundred meter drop. Looking closely at the swath one can spy what appears to be a rough hilly area then marked fluvial erosion and channels and finally a low spot- funky basin. Perhaps I'm reading too much into this but it seems to be there in the data and its kinda fun to do!
EDIT: yes I know that 'basin' at point b may be a plateau! given its radar bright appearance. However it kinda reminded me of that area in T 30 immediately to the east of Kraken that appears to blend with the lake and is also radar bright.

[titanicrivers]

Hey - that's brilliant, thanks!!

I see that the Adiri high is nicely placed to fit with catastrophic eastward flow at the Huygens landing site.

The elevation gain with the Western edge of Adiri and the net higher ground (possibly from the linear chains of hills) seems consistent however the eastern ends of the T8 swath shows greater elevation decrement in the northern most part of the swath. The Huygen's landing site is a bit south of that, where elevation change seems more modest and hill chains more prevalent. For the graphic below I used the SAR monopulse radar mode elevation data from Zebker et al https://www.sciencemag.org/cgi/content/abstract/324/5929/921 and mapped it to a moderately high (128 pixel/deg.) resolution T8 swath obtained from Perry's SAR radar swaths and swath map compilation. Realizing the elevation measurements may have some inherent error for such zoomed in sites, the color scheme nevertheless produces a pleasing end graphic of the HLS (Huygen Landing Site).

[ngunn]

That is nice, indeed, even though the resolution of the altimetry must be comparable with the size of the entire final image! Nevertheless it's not hard to imagine that if a large volume of rain fell suddenly on Adiri a significant portion could end up sliding off down the regional slope in the general direction of the landing site.

(Only a few days now, and we should be able to get back on topic. )

[ngunn]

Looks like Cassini has been lucky with the weather this time:

http://saturn.jpl.nasa.gov/multimedia/imag...3/N00142742.jpg

[volcanopele]

Are you telling me we actually saw clouds, lots of clouds, in an observation titled CLOUD001?!? Balderdash!

EDIT: actually, this was NPLCLD001, still same idea...

[remcook]

Lots of them!
http://saturn.jpl.nasa.gov/photos/raw/rawi...?imageID=202037
Also slightly visible in the MT1 filter.

[volcanopele]

Blar!! Another one!??!

I WANT sleep!

[titanicrivers]

Me too ....
Approximate location below.

[belleraphon1]

How beautiful those clouds look.

I still have to pinch myself on occassion. That I can sit here at a PC and pull up images showing weather on a world more than a billion miles away.

WOW.

Craig

[titanicrivers]

There's not only beauty in those clouds but also some intrigue !
That long streaking cloud at 60 deg N and between 240 and 270 longitude commonly is found southeast of Kraken. One wonders if
Kraken has some influence on the clouds location. However, two 2009 summary papers on this matter one by Rodriguez http://www.nature.com/nature/journal/v459/...ature08014.html and the other by Brown http://www.gps.caltech.edu/~mbrown/papers/...louds_final.pdf suggest the surface has but little influence on cloud appearance in north polar regions; rather the global circulation and subsidence and condensation of ethane enriched air into the colder troposphere control cloud appearance and location. EDIT (I may be wrong but I believe Brown has suggested that there may be some lake-effect cloud formation at times at lower altitudes poleward of 50 deg N. http://lanl.arxiv.org/abs/0809.1841

[ngunn]

One wonders if Kraken has some influence on the clouds location.

One certainly does. Evaporation from Kraken Mare, especially from its southern arms, should be in full swing by now. It's one of those 'obvious' things that it's hard to imagine will never be reconciled with theory. Nevertheless the scientists must proceed from facts and, when necessary, take the long way round.

I'm hoping these observations will yield some good information on cloud movement and atmospheric circulation as intended. Who will be first with the movie?

[remcook]

Titanicrivers- I don't think these are the ethane cloud. I don't think you can see that one with these filters. These will be thicker, lower methane clouds, like Brown's lake-effect clouds.

[titanicrivers]

Titanicrivers- I don't think these are the ethane cloud. I don't think you can see that one with these filters. These will be thicker, lower methane clouds, like Brown's lake-effect clouds.

Agreed. But my understanding (perhaps incorrect) was that they were still influenced by the global circulation and tropospheric flow rather than arising from ground based structures.
The second Brown et al paper on lake-effect clouds (?published) does provide some convincing evidence for an evaporative effect from the North polar lakes and seas with its polar map of these lower streaking clouds abundance on systematic evaluation of Titan images from several sources including VIMS, ISS and ground based observatories. (in the paper EAST rather than WEST longitudes are referenced on their plots differing from the ISS Cassini plots; that the reason for rotating the Brown polar plot 180 deg; clouds located in ISS are green and by VIMS are in red in the figure)
Brown predicts these lower altitude clouds will become increasingly abundant as the northern hemisphere of Titan gets increasing solar insolation over the next decade.

[remcook]

Yes, global circulation models also predict these kind of clouds there. They also predict they will increase with time at the moment.
Interesting paper in this respect:
here
Composition of the seas seem to be important

[ngunn]

I haven't read the paper but the abstract says that the model makes the lakes grow in summer and shrink in winter. It will be interesting to see if this or the opposite happens - or neither. North pole HiSAR is on the way. Islands may appear or disappear.

[ngunn]

I think it's worth comparing the cloud location with the global elevation map. (See posts 5 and 9 above and Mike's nice images today in post 68 of 'cloud hunting') Let's suppose the seas are loading the air with methane at and above 60N and that the air is moving eastward. The highest region along the 60N circle is around longitude 220-230. The longitude range 270-230 where the clouds congregate seems to coincide with the most significant regional upslope for E-W winds at that latitude.

[titanicrivers]

I think it's worth comparing the cloud location with the global elevation map. (See posts 5 and 9 above and Mike's nice images today in post 68 of 'cloud hunting') Let's suppose the seas are loading the air with methane at and above 60N and that the air is moving eastward. The highest region along the 60N circle is around longitude 220-230. The longitude range 270-230 where the clouds congregate seems to coincide with the most significant regional upslope for E-W winds at that latitude.

A polar SARTopo overlying SAR swaths was published (Fig. 11 of Stiles et al paper http://dx.doi.org/10.1016/j.icarus.2009.03.032 There are topographic variations of 500-1000 m in several localized areas near the large lakes and seas and both to the east and west of them. The data is still sparse. The overall polar surface seems fairly flat above 50 deg N. (from Zebker et al Fig. 1) https://www.sciencemag.org/cgi/content/abstract/324/5929/921, although the shape-elevation map (Fig 3 same paper) shows some N polar upslope as one approaches 180W longitude. There is little coverage of SAR along the 180 N longitude however. The T 30 swath and monopulse SARTopo does show some evidence of this upslope. (as mentioned in post #9 in this topic). More upslope occurs in the N to S direction on most swaths. The lakes and seas seem positioned to contribute methane evaporation to the air. I am not sure of the surface winds at 60N as the recent wind map (based on dunes) doesn't have much coverage there. All in all it seems the clouds may have multiple factors contributing to their development. (Cloud map from Brown et al http://lanl.arxiv.org/abs/0809.1841

[ngunn]

OK I've tried to do a graphic (please don't laugh).

Approximate correlation of regional elevation and clouds for 60 N on Titan - elevation colours cropped from the Zebker et al thumbnail, clouds from clip art:

Attached File(s)

 Titan60Nelevationandclouds.doc ( 57K ) Number of downloads: 196

 

[climber]

[ngunn]

Nice to know the link works.

[climber]

[HughFromAlice]

Titan is just such an interesting place! Looking at those North Polar clouds is really exciting - since you've had a few in this thread I thought I would post a few pics I did to try and get a slighter different perspective on those clouds. I would like to process them more but it's getting late.

1 Original..... .....2 BW bump map smoothed etc ....

3 False Colour 1.... .... 4 False Colour 2....

[Juramike]

Lots of them!
http://saturn.jpl.nasa.gov/photos/raw/rawi...?imageID=202037
Also slightly visible in the MT1 filter.

So, if we are seeing a slight brightening in the MT1 filter, does that imply that these are methane clouds and not ethane clouds.

(The MT1 usually seems to show a slight darkening in the polar region, I always assumed this was due to "non-methane" stuff like complex organic products absorbing light)

Or is this just an albedo effect?

-Mike

[remcook]

This mostly means the clouds are pretty high. This is at a wavelength where methane is absorbing more than in the surface windows, so light does not reach the ground, but you're seeing stuff (clouds and haze) reflecting from somewhere in the troposphere. I think methane and ethane reflect very similarly at these wavelength (both are not very absorbing compared to the haze - but I could be wrong, can't find the data for ethane at this wavelength at the moment). A darkening at high latitudes probably means there's more haze or other absorbing stuff.

Everything you see is an albedo effect