Terraformed Venus

[acrosome]

Sorry, my bad I meant subpolar. Sorry if that confused you. You have the ( <45 degree) polar currents right it's the subpolar ( > 45 degrees) currents that need work.

Also look at your source image, the really detailed one (2nd one) it only shows up to 60 degrees and doesn't show the full 90 degrees lat, I think this is why your getting a little confused. Your not getting the full picture. The current does go eastwards but it's around the 45 parallel. Also note the antartic subpolar, it is more of what I was getting at.

Well, that more detailed second map I linked show a broad eastward circumpolar current from about 45S to >60S, so that's what I tried to emulate. The first (more simple) map also shows it at 60S. I figured that the westward subpolar currents would be at >60S, and didn't really bother to chart them. So you're basically saying to present the circumpolar current as being at a lower latitude than 60, right?

What messes me up, as I mentioned, is that I have landmasses at 60S in both the north and south and I'm not sure what effect that will have. Thus my question about if I should just model those after the far northern Atlantic, or the small gyre through the Bering Sea, etc. on the more detailed map.

As to why I switched the directions, if you look at the two sources your using you will see that around 45 degrees latatude the currents travel eatward then the current splits at a landform/ice with warm moving north and cold going south. There is a long scientific reason why this happens but suffice it to say it's due to the rotation of the planet. The currents you are mapping are the surface currents wich are created by the prevailing winds caused by Hadley cells. The basic idea is closed loops, with the east/west flowing currents traveling until they are split by land then warm goes towards poles and cold towards equator.

Ah, never mind- I see it now on that detailed map. I had a chart reading failure there for some reason. I'll have to fix that.

With Xartanga and Lada the polar current travels eastward until it encounters land (the southern islands of Lada for simplicities sake) at this point the current splits with warm going towards the pole and cold going towards the equator closing the loops. That split doesn't occure prior encountering an obstical (land). {Not entirely true what you see in real life is a warm current drift north with the greatest concentration along the costs (warm current only) the cold current doesn't doe the same thing.}--> ignore this if it confuses you it's not important.

I went to pretty extraordinary lengths to close loops, actually. (Note the numbers next to the currents.) But, as I said above, I have some reworking to do...

I'm checking your links, now.

EDIT:

That first one is a damned cool chart of arctic currents.

But that third link of yours is what I'm talking about- the circumpolar current looks like it runs as high as >60S for about 3/4 of the way around Antarctica. Still, it clearly does not for 1/4. So I can tweak that, too.

Looking at my poles in orthographic projection on GProjector I'm starting to think that I need to model both of them on the Arctic rather than the Antarctic.

I'm going to go cry into my pillow for a bit, and once I've recovered my composure I'll start over. It may be a while.

[talisid]

First off, I want to say that your project - both the idea and execution - are awesome and inspiring.

Second, since my knowledge is lacking, instead of offering advice, I offer a resource that you are (I assume) unlikely to encounter online, an inset from the 1966 National Geographic Atlas of the World. I'm like 99.5% sure this counts as fair use since it is far less than 5% of the book, is being used for "educational" purposes, and would have to have had its copyright extended to not be in public domain by now. That said, if I should remove it let me know.

It shows warm and cold currents, along with prevailing wind direction. I can take better photos or maybe get an actual scan of it if you want, and I hope that it will at best help out and at worst not ruin anything!

Keep up the awesome work.

[ascanius]

I went to pretty extraordinary lengths to close loops, actually. (Note the numbers next to the currents.) But, as I said above, I have some reworking to do...

I'm checking your links, now.

EDIT:

That first one is a damned cool chart of arctic currents.

But that third link of yours is what I'm talking about- the circumpolar current looks like it runs as high as >60S for about 3/4 of the way around Antarctica. Still, it clearly does not for 1/4. So I can tweak that, too.

Looking at my poles in orthographic projection on GProjector I'm starting to think that I need to model both of them on the Arctic rather than the Antarctic.

I'm going to go cry into my pillow for a bit, and once I've recovered my composure I'll start over. It may be a while.

Lol.. You got this. besides all you need to change is the subpolar currents to the opposite direction, it's an easy fix. I don't think you need to worry so much about the subpolar currents what you have works well once you change the direction. keep it simple first then add complexity. One thing could you add the lines of latatude. Keep up the good work. I'm very interested to see how you do the atmospheric pressure systems and climate, though I don't envy you with all the microclimates your going to have to do.

Also. I think the reason why the antartic map show the current going east until 60 is because there is nothing (landform) to break up the currents flow. The currents don't exactly travel in a east west line but drift polar if they are warm and equatorial if the cold. With antartica the currents more or less run parallel with the continent. However if you look at Talisid's map below you will see that very close to coast of antartica the current is westward. Your map has enough subpolar landmass to change things more towards what I showed you in the paintover.

First off, I want to say that your project - both the idea and execution - are awesome and inspiring.

Second, since my knowledge is lacking, instead of offering advice, I offer a resource that you are (I assume) unlikely to encounter online, an inset from the 1966 National Geographic Atlas of the World. I'm like 99.5% sure this counts as fair use since it is far less than 5% of the book, is being used for "educational" purposes, and would have to have had its copyright extended to not be in public domain by now. That said, if I should remove it let me know.

It shows warm and cold currents, along with prevailing wind direction. I can take better photos or maybe get an actual scan of it if you want, and I hope that it will at best help out and at worst not ruin anything!

Keep up the awesome work.

Nice map. I'm pretty sure that it counts as fair use.

[acrosome]

Lol.. You got this. besides all you need to change is the subpolar currents to the opposite direction, it's an easy fix.

Lol... I never drew subpolar currents. That's what I'm saying. The currents near the poles for which that you switched the direction were my 60-degree circumpolar currents, which it looks like should indeed be going east as I had them. Circumpolar. I think we got messed up on terminology. (See that first map I posted- that's the terminology I'm using.) You seem to be saying that I should make my circumpolar current lower than 60 degrees, which I'll buy- I'm working on new currents, basically starting from scratch.

However if you look at Talisid's map below you will see that very close to coast of antartica the current is westward.

Yes. And those are subpolar currents, not circumpolar currents. I agree- and knew all along- that subpolar currents are westward. You seem to want me to draw maps without circumpolar currents, regarding which:

Your map has enough subpolar landmass to change things more towards what I showed you in the paintover.

The landmasses near but not on the poles (unlike Antarctica which is on the pole) are what I was talking about when I mentioned that maybe I should be making my polar currents look more like the Arctic than the Antarctic. The Earth's crowded northern pole prohibits a circumpolar current since there's land sitting on 60N, and instead you get those odd lobes off of the northern gyres, as in those currents near Alaska and Scandinavia on that second map of mine. Looking at my Cytherian poles in orthographic projection on GProjector I suspect that my southern pole at the very least probably has very Arctic-like currents- similar to those maps of Arctic currents that you posted. Here's the south pole (with my old currents- ignore them):



Another thing this view shows is (I think) your point about my eastward/clockwise circumpolar current. I have it at too high a latitude to allow room to squeeze the westward subpolar currents in.

So now I'm probably just down to puzzling out the northern polar currents. For completeness' sake, here's the north pole:



When I next post currents I think you'll see what I mean. I might just post the major currents first to see what you think of them. But I got sidetracked filling basins in Wilbur for a while...

[johnvanvliet]

mind you the currents will be opposite of the earths
venus rotates backwards and very SLOW

a day is longer than the year
so not much in the way of Coriolis effect from the rotation

a bit od an oldish quote

I also found GTDR data from the Magellan mission, which is topographical data on Venus. I thought I'd run it through some manipulations in Wilbur when I get a chance and see what pops out. Unfortunately, one pixel is 4.6km, so it isn't terribly detailed, and there are a lot of holes and artifacts in the data, but I still think it can help me figure some things out.

Hmm... I guess that I have a Wilbur question... given data like that can Wilbur for instance double the number of pixels (to 2.3km/px) by extrapolating elevations or somesuch? (I have yet to download Wilbur- I have to dual-boot some sort of Windows on my laptop, first.) I wouldn't mind trying to do a nice job with Wilbur on some small area, like Tellus or Eistla, or maybe Beta. (I understand that Wilbur works best on smaller scales.)

if you still need a DEM
here is one i made that is 16384x8192 px
the below link is no longer working
those that need it have it

https://drive.google.com/file/d/0B6Z...ew?usp=sharing

from
http://pds-geosciences.wustl.edu/mgn.../mg_3002/gtdr/
holes filed and upscaled using a SFS algorithm on the radar mird FULL data
http://pds-geosciences.wustl.edu/mgn...r-full-res-v1/

[acrosome]

mind you the currents will be opposite of the earths
venus rotates backwards and very SLOW

a day is longer than the year
so not much in the way of Coriolis effect from the rotation

If you look closely, my maps are rotated 180 degrees. I've flipped them so that "east" is the direction that the sun rises. Yes, this swaps the north and south poles, but it also means that I can more directly model currents and winds on Earth. Or to put it another way, the way that I have these maps oriented means that I can use Geoff's Climate Cookbook and Pixie's method as-is. I discuss this briefly in the second or third post.

Likewise, for terraformation purposes the rotation has been sped up to a 24 hour day and a bit of axial tilt added. (This is both to simplify worldbuilding and also to try to disguise the identity of the planet from RPG players- something that is hard with Mars.) Speeding up rotation will deform the planet into a more oblate spheroid, adding about 40 miles of equatorial circumference, which I'll assume is new rifting. I'll add the rifts where I need them to drain basins and such. This all also gives me an excuse to restart vulcanism in spots. (Though no one really knows if Venus is still volcanically active or not. It doesn't work like Earth- there are no tectonic plates. One theory is just massive resurfacing via volcanic events every few million years.) I haven't decided if Venus has been moved out to a wider orbit, but probably.

That's a DEM of Venus? Well, if it's better than mine (and it almost has to be) I'll definitely be checking it out when I get home. That's huge, though- it might break my MacBook! Thanks! Though on the downside that probably means that I'm back to the drawing board again... My main concern is all the damned streak artifacts and holes in the Magellan data. Did you fix those? That's what consumed most of my time- fixing those and cloning data into the holes (poorly- I'm no artist).

[acrosome]

Wow. Your DEM is much better than mine. I can actually see the texture of ridgelines in the mountain ranges (which I knew were there from looking at USGS radar maps of the planet). And it lacks all of the holes and artifacts that I have in mine.

But your data generate much different coastlines than mine when I play with it in Wilbur! Is this Magellan data, or is it from some other source? Because if it is Magellan I would expect it to match my coastlines.

Nonetheless, this is clearly better than mine, which means starting over again from scratch...

Thanks?




Other old tries:

[johnvanvliet]

Is this Magellan data, or is it from some other source? Because if it is Magellan I would expect it to match my coastlines.

it is
cleanning up the data from here
http://pds-geosciences.wustl.edu/mgn...02/gtdr/sinus/

changed it a bit that sinusoidal projection map is VERY noisy

then it was merged with a data set derived from the RADAR reflectance map using a Shape from shade program to make a" high frequency " layer for the height data

then joined the high freq and low freq information into one image
this also means it is no longer 100% scientific accurate


the map i posted on my G-drive is using this mapping group ( i use ISIS3 gis )

 Group = Mapping
    ProjectionName     = SimpleCylindrical
    CenterLongitude    = 0.0 <degrees>
    TargetName         = Venus
    EquatorialRadius   = 1737400.0 <meters>
    PolarRadius        = 1737400.0 <meters>
    LatitudeType       = Planetocentric
    LongitudeDirection = PositiveEast
    LongitudeDomain    = 180 <degrees>
    MinimumLatitude    = -90.0 <degrees>
    MaximumLatitude    = 90.0 <degrees>
    MinimumLongitude   = -180.0 <degrees>
    MaximumLongitude   = 180.0 <degrees>
   # PixelResolution    = 0.0 <meters/pixel>
    Scale              = 45.5111111111 <pixels/degree>
  End_Group

[acrosome]

it is
cleanning up the data from here
http://pds-geosciences.wustl.edu/mgn...02/gtdr/sinus/

Ah, yes, so it's mostly Magellan data.

Well, it's an f-ing Thing Of Beauty.

changed it a bit that sinusoidal projection map is VERY noisy

Truth.

then it was merged with a data set derived from the RADAR reflectance map using a Shape from shade program to make a" high frequency " layer for the height data

then joined the high freq and low freq information into one image
this also means it is no longer 100% scientific accurate

I had come to suspect that it used a different geoid or something. So if you used radar reflectance then all the surfaces that are radar reflective (viz. rough/young) will look a bit higher than reality in this DEM? Or am I misunderstanding?

the map i posted on my G-drive is using this mapping group ( i use ISIS3 gis )

Code: ...(snip)

Now you're getting a bit beyond me. Actually, for the most part, more than a bit. So you mapped it as a perfect sphere? (Actually, Venus is pretty damned close to a sphere, isn't it?)

So, granted that the nearly Godlike terraforming that I'm invoking here will reshape the world considerably, I'm mostly concerned with my sea level being appropriate. Given your manipulation of this data, if I set a given elevation in your DEM to sea level (in Wilbur e.g.) would that be close to accurate re: water finding it's level, or would it be totally off?

Here's a decent sea level:

[johnvanvliet]

so you are going with NORTH on the bottom of the map

as to your "sealevel" and mine

the image "16kVenusDEM.tiff" the mean average is 8065

however if you add the value "6039999" to the pixels you will get the Radius in Meters but i only scaled it to the min/max values