Wave pattern

• by angi60

  WOW! Fascinating wave-like patterns! Are these an aeolian feature?

  Posted June 7, 2013 12:07 AM

• by mschwamb scientist, translator

  Those could be dunes.

  Cheers,

  ~Meg

  Posted June 7, 2013 1:09 AM

• by angi60 in response to mschwamb's comment.

  Thanks Meg. Yes I thought they looked like dunes. but it's the first time I've seen an image like this. It looks very artistic!

  The Live Chat was excellent. It's fascinating to find out exactly what you gain from the simple tasks we do, and how it impacts on Planetary Science. Also it's great to know that what we do is so appreciated! So I'll be classifying as usual later, but with a renewed vigour!

  Regards,
  Angi

  Posted June 7, 2013 8:16 PM

• by mschwamb scientist, translator in response to angi60's comment.

  Glad you enjoyed the live chat (and that someone was watching yay 😃 )
  ~Meg

  Posted June 7, 2013 8:41 PM

• by JellyMonster in response to angi60's comment.

  Couldn't resist...

  

  Posted June 7, 2013 8:54 PM

• by Kitharode moderator

  Good find Angi60. Thanks for the rotation JM.

  Dunes must be a possibility Meg, but I'm gonna take a look at the 'bigger picture' before I decide.

  Posted June 7, 2013 9:04 PM

• by mschwamb scientist, translator

  Depending on the scale, could be more like wind ripples on second thought depending on the scale, but definitely sand being blown into ripples

  ~Meg

  Posted June 7, 2013 10:53 PM

• by angi60 in response to mschwamb's comment.

  Haha Meg , I'm sure there were plenty of people watching 😃 It's interesting how the ripples seem to be in all different directions, and how the areas either side appear to be flat (a different depth of sand or different soil, maybe - that's a non-expert's view of course).

  JM: Thanks for taking a turn (literally!) and enlarging the image 😃 It's always helpful.

  Kitharode: Good to see your input. I'll be interested to see what you conclusions you come to.

  Posted June 7, 2013 11:14 PM

• by Kitharode moderator

  Help please. Can anyone confirm the direction of light in angie60's original image? I'm aware that they are generally showing light coming in from lower right, but it's important that I know this for sure for this image.

  Posted June 10, 2013 11:15 PM

• by Kitharode moderator

  PS to the above. I can't place angie60's image into the full HiRise image. Can anyone see where the wavy lines are in the full image? It would be most useful to know. Thanks.

  Posted June 11, 2013 5:00 PM

• by p.titchin in response to Kitharode's comment.

  yes, found it on the RGB col.nonmap. One tenth the way up from the bottom of the strip, in the lighter band just below the start of the very dark area of numerous fans and blotches.

  Posted June 11, 2013 8:18 PM

• by p.titchin in response to Kitharode's comment.

  forgot to say , in addition , wavy lines are pretty much in the centre of the strip.
  Pete.

  Posted June 11, 2013 8:23 PM

• by angi60

  Thanks guys. I'm glad I've sparked some debate. Kitharode, I can't wait to see where your thoughts are going!

  Posted June 11, 2013 10:43 PM

• by wassock moderator

  Most of the nearbye HiRise images are named something liker "Jeans crater dune monitoring".........

  Posted June 11, 2013 11:25 PM

• by angi60 in response to wassock's comment.

  Thanks for that Wassock. I'll have a look at the other images.

  Posted June 11, 2013 11:41 PM

• by JellyMonster

  I think it is one of those images where whichever way it is turned, it will look the same.

  Posted June 12, 2013 9:53 AM

• by Kitharode moderator in response to p.titchin's comment.

  Pete: You're a star. You sent me straight to it first time. Many thanks. The problem was that I'd followed the HiRise link under the image and then clicked on the image at top of that page. This took me to the 'sloping strip' image which is actually the top half of the RGB image you pointed me to. Looks like I've learnt something useful there, so thanks again.

  Angie60: My thoughts have turned to ice !! (woooo deya diya deya diya) * 😛 * (More later, perhaps).

  Posted June 12, 2013 5:31 PM

• by p.titchin in response to Kitharode's comment.

  glad you found it. I am always worried that I my simplistic way of describing what I have seen is not up to the new high tech stuff. I expect you noticed (Angie60, you might be interested as well) there is a similar pattern of dunes just below the image we are discussing .As a naive thought, I notice that these patterns,(ive seen several before when Ive been marking)appear to occur on the windward sides of scarps.I'm sure this can be modeled , my own interest has been in met, and I can see how these might be formed as a prevailing wind against gravity. Glad to be of use.
  Pete

  Posted June 12, 2013 7:43 PM

• by Kitharode moderator

  Hey, that's good stuff Pete. By the way, simplistic is fine by me. 😉

  The "prevailing wind against gravity" idea is interesting indeed and it is not hard to visualise that scenario. Two things I'd like to ask: Are you suggesting that it is windblown sand/dust/grit that is being shaped into these ripples, as suggested by Meg? How do you decide which is the windward side of a scarp/dune? (I agree with your wind direction, but I'm not sure I'm right).

  Posted June 12, 2013 8:08 PM

• by p.titchin in response to Kitharode's comment.

  We would need to know the time scale over which the ripples formed, and have images during the formation to get an idea of the wind . Does not appear to be much wind effect on the nearby vents when this image was taken. Sure do make striking images though!

  Posted June 13, 2013 9:56 AM

• by p.titchin in response to Kitharode's comment.

  I wonder like Meg if these start as wind blown particles, but looking at the other similar areas nearby on the HiRise, and their boundaries, they look as if on slopes they then 'slump', If there was still wind, then I suppose that this would then affect the ridges formed in the 'slumps'

  Posted June 13, 2013 10:16 AM

• by Kitharode moderator

  I've going to stick my neck out and suggest that the wavy lines are not sand dunes or dust ripples. Instead of wind-blown dust I suggest we should think wind-shaped icelayer. The more I look, the more I see ice-ripples.

  Posted June 13, 2013 10:06 PM

• by angi60

  Glad to see the debate's still going on! Just as things started to get interesting I lost my broadband all yesterday. 😦 I don't know enough to know which side of the debate to support but I'll follow it avidly. May the best man win- haha 😃

  Posted June 13, 2013 11:02 PM

• by Kitharode moderator

  With Candice, Anya, and Meg doing their lurking about thingy it'll probably be a woman who sorts this one out Angie60. Fortunately it's not a contest, just a bit of 'science at street level'. 😃

  There's no doubt that there's loads of dust around in the image. On the right of the image a smooth, apparently wind-swept, dune feature is blothed and stained with dust. On the left we see the familiar blotches and linear venting of dust through the icelayer.

  So why are the ripples so clean and shiney? Where's the dust? Could local winds be so thorough in cleaning the ripples, yet so selective in the area that is cleaned?

  I'm aware that I'm not offering any evidence in support of my 'ripples in ice' idea - But I'm working on it 😉

  Posted June 14, 2013 7:17 PM

• by p.titchin in response to Kitharode's comment.

  As this is the chat forum, Can't resist another thought Angie 60 and Kitharode,, If you have seen Cotswald stone tiled roofs, each line of tiles gets smaller as they go up the roof. These lines of n?ice humps start small and each regular row gets bigger as they go up until they end at the top with a much more irregular line of humps of much less regular size, some very large. Like you Kitharode I cant begin to explain, but if you ski, I guess they make great moguls!

  Posted June 14, 2013 7:43 PM

• by Kitharode moderator

  So it's the roof of a martian eco-house and the little green people live underground - Nice idea. 😛

  We do that sort of roof in west yorkshire too. I've got one on my 400yr old barn !! (Probably different stone, but same method).

  Slightly more seriously and back to the ripples: We know from elsewhere in the discussions that slope is important, not only in the shaping of some fans, but also in capturing sunlight during the sublimation season. Let's imagine that, for whatever reason, the seasonal icelayer at this place formed in an undulating wavelike manner. When sunlight returns to the area we might expect the sunlit side of the waves to sublime faster than the shadowed side. This action, coupled with local turbulant wind, might well produce the rippled sculpted effect seen in the image.

  Ripples on the top of the icelayer would not necessarily disturb the underlying dust layer, so it wouldn't show. Maybe, perhaps.

  Posted June 14, 2013 9:08 PM

• by wassock moderator

  Kith, have a look at the nearbye images on HiRise, some are from the autumn and still have the same sort of features. So surface rather than ice sculpture

  Posted June 14, 2013 9:26 PM

• by Kitharode moderator

  That's well noticed wassock. I've got to agree that surface sculpting, rather than ice, would appear to be the case. I'd still argue in favour of an ice layer over the surface ripples (in the image above).

  Remind me please, how do I find 'nearby' images to a HiRise image?

  Posted June 14, 2013 10:36 PM

• by angi60

  I like the idea of Martian roof tiles!! What I still don't understand is, assuming that they're dunes, why is there such a variation in size and direction? And why are they surrounded by blotches rather than fans if there is that amount of wind? Just wondering! And, yes Kitharode it's usually women who sort things out :-X haha. Though I'm not able to sort this out!

  Posted June 14, 2013 11:03 PM

• by wassock moderator in response to Kitharode's comment.

  When you are on the HiRise info page scroll down to below the date and position box and there's a list on the righti

  Posted June 14, 2013 11:40 PM

• by Kitharode moderator

  It's probably safe to assume that the wind does not blow all the time. There may well be a 'season of wind' and a 'season of still' following the seasonal cycle of the icelayer. (I'm guessing). Assuming wind-blown dust dunes on the surface we need available, relatively ice-free dust, with 'dune force' winds blowing, so I'd guess late spring/summer for dune formation. When winter sets in the icelayer forms and, perhaps, the winds subside for the blotchy season.

  Variation in size and direction: There is a vague similarity, to my eye at least, between the wavy line ripples and the 'interference pattern' of waves on a pond as the expanding circles meet and overlap. Might there be a season of wind that blows along the valleys between the larger, smooth dunes, which deflect and interfere to produce turbulence in the wind?

  As I said, I'm guessing. 😉

  Posted June 15, 2013 12:03 AM

• by Kitharode moderator

  PS. Thanks wassock.

  Posted June 15, 2013 12:07 AM

• by wassock moderator

  Not sure if I read this or it was mentioned in the team talk. In the North there are dunes which are good indicators of prevailing wind but often the fans which form on them show a different direction. So prevailing wind varies with season.

  Posted June 15, 2013 12:13 AM

• by angi60 in response to Kitharode's comment.

  Thanks Kitharode and Wassock. Makes more sense now 😃

  Posted June 15, 2013 12:48 AM

• by mschwamb scientist, translator in response to wassock's comment.

  This looks like a good description of some of the processes and types of sand dunes that can form. As wassock pointed out, it's the long term year-long/decade long average wind directions and trends that will drive the dune shape or wind ripple shape, but the wind doesn't have to permanently fixed in those directions all the time.

  Cheers,

  ~Meg

  Posted June 15, 2013 2:26 PM

• by Kitharode moderator in response to mschwamb's comment.

  Good link. Thanks Meg. Looks like sand dunes/ripples wins the days. Sculpted ice is no more. So it seems like we're tracking wind patterns - Sounds like fun.

  Posted June 15, 2013 7:14 PM

• by angi60 in response to mschwamb's comment.

  Meg - Thanks very much for the link. I've found it very useful as I know precious little about sand dunes on Earth, never mind Mars! I've learnt so much since being involved with PlanetFour 😃

  Kitharode- Sorry your 'sculpted ice' theory bit the dust (ahem!) 😦 It was interesting while it lasted though!

  ptitchen - I'm sure you'll find the above link of interest too. Thanks for joining the discussion.

  Posted June 15, 2013 10:51 PM