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acrsome
12-15-2013, 01:22 PM
Howdy, All.

As I mentioned elsewhere (http://www.cartographersguild.com/member-introductions/25461-another-new-guy.html) my pet project is going to be a terraformed Venus. I plan to use it for an ultra-low fantasy (no magic) campaign set a few millennia after a cataclysm. Here's a preview:

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This is a USGS topo map of the planet with a sea mask and 5-degree lat/long lines superimposed, Mercator projection, and it only goes to 57-degrees north and south. (At the equator a 5x5-degree quad is roughly 328 miles square, so almost 108,000 sq miles- just a bit bigger than Colorado.) It also is compressed quite a bit so that I could post it here- the original is over 27000 px across. I'm going to use this to guide my work on smaller regional maps. I'll also use this to figure out climate.

As a bit of a warning- It'll probably take me years to get any work done on this, so don't expect updates often.

Here are the prevailing winds, before I take into account the continents:

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If it looks backwards, remember that Venus rotates the other way- the sun rises in the west.

foremost
12-15-2013, 03:37 PM
Sounds like a very neat idea :)
Excellent detail of all the little islands, looks like back-breaking work.
Are those mountains or swamps?
No pressure on updating quickly, but when you get things done, please do let us know.

FM

acrsome
12-15-2013, 03:57 PM
They are mountains (real planetology). I'm not planning on going with the classic "Venus as a swamp-planet" motif.

And on another forum someone just pointed out that I could rotate the map 180 degrees to disguise the fact that the sun rises in the west, to confound those who might otherwise recognize it. Hmm.

Overview:

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Prevailing Winds:

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I'll presume that the Powers That Be decided to just designate east as "the direction the planet spins," and north is "to your left when facing east," etc. The actual magnetic character of the poles really should have little to do with such things.

gilgamec
12-17-2013, 03:13 PM
As part of the terraforming process, has Venus's rotation been sped up? Otherwise, a single day will last so long (240 Earth days or something) that I'm not sure that you can use Earth-based climatic theory. For example, the "day side" of the planet would be receiving light and heat for (Earth-)months at a time, so pressure zones that would form would be more based on continent/ocean size than axial inclination.

acrsome
12-18-2013, 01:20 AM
Yes, I'm proposing that the rotation is sped up. 116-day solar days are pretty unworkable. Speeding up Venus's rotation will deform it into a more oblate spheroid- it will bulge at the equator, causing new rifting perpendicular to the equator. This will be roughly 40 miles of extra circumference, so I figured I'd add a new 2-mile rift every 20 degrees or so, plus lesser ones where needed. (This actually gives me a way to drain some basins that would otherwise be inland seas.)

I'm also giving it 20-degrees or so of axial tilt, to generate seasons.

What I haven't decided is whether I'll keep Venus in the same orbit with some sort of sunshade or if I'll move it to a new orbit. Keeping it where it is has the advantage that I need not add a moon to have appreciable tides- solar tides would be about as strong as Earth's lunar tides. Not having a moon probably means more perturbation of axial tilt, but that's an issue on scales of tens of thousands of years. And a Venus year would still be only 224.7 days.

OTOH moving it to a new orbit avoids the need for constant station-keeping on the part of a sunshade. And, heck, if my planetary engineers can move Venus then they might as well snag Triton as a moon for it. About 1/3 of Triton's mass could provide volatiles for the terraforming, too (mostly nitrogen and water), leaving a slightly smaller moon to orbit as a satellite. It would also lengthen the year. Options include moving Venus into a binary relationship with Earth (which would require ejecting the Moon to avoid the N-body problem), moving it into a binary relationship with Mars, or slipping it into its own orbit midway between Earth and Mars. (I worry that this would do something terrible to the orbital resonances of these planets, though.) It cannot be placed on the opposite side of the sun from the Earth, as L3 is unstable. So are L4 and L5 unless one body is much larger than the other, which would not be the case here- eventually they would collide or one would be ejected.

I'm tending towards the position that if my engineers can spin Venus and give it an axial tilt, then they are probably capable of moving it to a new orbit if they feel like it. But I'm not sure what I want for my campaign.

Anyway, here are some initial climate maps:

January

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The equator and 30-degree parallels are shown. The north and south map edge are at 57-degrees. The reddish pseudo-equatorial line is the ITCZ. Major landmasses are labeled.

July

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I'd appreciate if you all could point out glaring errors before I start scribbling a few hundred windsock arrows over the maps. :)

I used The Climate Cookbook (http://jc.tech-galaxy.com/bricka/climate_cookbook.html) and PhysicalGeography.net (http://www.physicalgeography.net/fundamentals/7p.html) as guides.

Oddly, I have in some ways recapitulated Earth on these maps- you can see how I have a North and South America, a Eurasia, etc. Thus I leaned on the latter website a lot. The wild card is that my Eurasia sits approximately smack on the equator, so if anyone has any ideas about that I'm listening. Looks like monsoons in Thetis and southwest Ovda?

Also, I can't quite figure out what to do about Alpha and Astkhik. Their land area is probably too low to have a real continental effect, so I think that I perhaps should do the opposite of what I show here, because they are in the equivalent of my Northern Pacific, which looks like it has a honking big low in January and a mellow high in July.

foremost
01-10-2014, 11:55 AM
Again, looks like this was a lot of work, tons
of little islands all over your map. Going to
make for a lot more work when the project
progresses. It's obviously been a few weeks
since you updated, so I hope you are still
going.

My question would be "Why is the heat-band
not directly on the equator?" Maybe this is
as it should be, and I'm interested to know
why.

Water takes a longer time to heat up or cool
down than land does, and it's also going to carry
some wind currents along with it. The temperature
should also fluctuate throughout the seasons. Does
Venus have seasons?

Anyway, the coastal areas will have more balanced
temperature, thanks to proximity to the water. Inland
areas might be bone-dry and wicked hot as well.

I'm no expert on this, and if you have information
from those websites you mentioned, please share!

Neat project, hope you continue.

rgcalsaverini
01-12-2014, 06:11 PM
Great to see a map with such realism! I tend to rush to drawing before settling some necessary things before. I will be following this eagerly!

Nathan
01-17-2014, 06:33 AM
Oh ! I really like that !
Impressive !

Caenwyr
01-17-2014, 08:58 AM
Great to see a map with such realism! I tend to rush to drawing before settling some necessary things before. I will be following this eagerly!
Seconded! No patience whatsoever here... though I really should work on that! My sincerest compliments to your perseverence, acrsome!

acrsome
03-25-2014, 10:17 PM
Yes, I'm still working on it. Exactly two days total since my last post, but I warned you all about that. Careers suck sometimes...

@foremost: Those aren't "heat bands", they are high- and low-pressure zones. And the ITCZ is just sort of a line near the equator with equal pressure north and south of it. I can't explain it in a pithy manner (especially since my own grasp of it is tenuous at best). If you're interested check out those websites I listed.

Venus terraformed the way that I'm proposing will indeed have seasons. It's been given more axial tilt, and its spin has been increased.

Speaking of which I wasn't happy with the previous climate maps, so I re-did them making some different assumptions. I also added winds and currents. I'm ready to start working out Koppen climate zones soon.

So, yellow are high-pressure zones, blue are low-pressure zones, and the green arrows are prevailing winds:

Here is July:

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Here is January:

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Here are currents, hot cold and indifferent:

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Recall that "hot" and "cold" are relative. I.e. a warm polar current can be colder than a cold equatorial current.

EDIT-- Does anyone have a nice 1000m contour map of the world or of North America, so that I have something to compare to while working out climates? My Google-Fu is failing me.

EDIT-- I decided that I don't like my first world-spanning map (the file size is simply too big to work with) so I'm currently working on re-doing it as eight regional maps instead. Luckily, I found a decent set of USGS base maps that includes the poles, so now I can cover the whole planet. Which is nice, because Ishtar Terra is damned interesting. I've also been struggling with Koppen climate zones, and I'm getting frustrated. I need the climate worked out so that I can decide which basins will be endorheic and which will be inland seas or lakes, etc. But some of these basin seas might be big enough to affect climate. Grr. It looks like most of northeast Aphrodite will be a Sahara-equivalent, and there are a few areas with true monsoons in Manatum and in that large bay at the west end of Thetis.

So, more will follow... eventually.

acrsome
04-19-2014, 11:20 PM
Here are some initial thoughts on Koppen Climates. Lines of latitude are in 15-degree increments (this is a Mercator projection that only covers to 57-degrees north and south).

Frankly, a map of biomes like the Hodridge scheme or like this (http://upload.wikimedia.org/wikipedia/commons/e/e4/Vegetation.png) is probably more practical and useful than Koppen climates, but it seems to be traditional to do the Koppen thing. I'll probably make a biome map later, and the Koppen climates will help me on that.

There are a lot of landforms that don't really have perfect analogues on Earth, so I made a lot of stuff up. For example, my huge Himalaya-like mountains are on the equator, so I used the equatorial Andes as a model for them somewhat, and made some SWAGs. (Actually they're not quite Himalaya-scale; the really tall mountains are in Ishtar.) A lot of my continents don't have a large north-south mountain range as in the Americas or Himalayan rainshadow like Asia, so I'm not sure how the east-coast and west-coast climates meet in higher latitudes without one.

My large Amazon-like Af rainforest is in eastern Ovda, since that's the only large chunk of tropical land on an east coast right on the equator. (Equatorial Phoebe is small in comparison.) I made eastern Atla somewhat similar, though.Generally, since so much of my land is in the tropics there is a LOT of Af, Am, and As.

So, I guess I'm making a jungle/desert world...

Ulfrun/Atla is a rough analogue of sub-Saharan Africa. Thus, that enormous BWh desert largely covering Zhibek and Artemis is a Sahara-equivalent. (There are no large mountain ranges to keep that desert from just cutting all the way across the continent.)

Eistla will be an Australia-equivalent. I may change the Umay-ene climate a bit and make it my Madagascar biome.

There is no good Europe-equivalent with an aberrantly high-latitude Cwa climate, unless it's Hathor and western Themis... but I was going to make Themis/Phoebe my South American biome, and make Beta my North American biome. (Ishtar is probably more like a Canada/Scandinavia bastard child.)

The only true India-like monsoon is that bit in western Thetis; the other Am climates technically meet criteria- like most of the the Amazon- but aren't the intense and brief raging torrent of the Indian Ocean monsoon.

This is all just preliminary, to help me make other decisions such as which low spots to fill as lakes and which to leave as endorheic basins, deciding where the big rivers will be, etc. Nonetheless, if anyone has any criticisms, fire away. My eyes were crossing in a lot of spots, so I'm sure that I have some egregious idiocy here, somewhere.

I'm still working on my newer maps that will show the poles as well. This is important, because there is a lot more of Ishtar down there, and that might end up being an important place. (I have to think of new names for these landforms...)

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.)

After sangi39 mentioned this inspired study (http://www.bristol.ac.uk/university/media/press/10013-english.pdf) on his Yantas thread I started looking around to see if there was any way I could run my world through the HadCM3L climate model, but I don't think that there is. Unless, of course, someone here happens to work for the UK Met Office or the Hadley Center... :)

A final point: I was going to name this world Sypherion, that being a fictional cognate of cytherean, which means "of or regarding the planet Venus." But then I found Max's map of the city of Yphyrion, and now I don't feel so clever...

sangi39
05-06-2014, 12:08 PM
So I've been meaning to reply to this for about 16 days now, but luckily it's all praise, since I don't feel like I know enough to point out any errors lol. Looking at your map and the Koppen climate map for Earth, though, has really made it clear to me that my climate map for Yantas was pretty damn wrong :P I mean I don't have tropical rainforests at the poles, but I seem to have been overly simplistic in dealing with certain climate zones :P

acrsome
05-07-2014, 10:28 AM
Oh, I just think that your climate map was a roughing-in, so to speak. As if you made a map with the suggested latitudes taken very rigidly, and painted in as bands, to use as a guide. I thought that's a great idea (and probably sufficient for any fantasy mapping needs). So I stole it :) and did something similar, but then looked at the real-world Koppen maps on Wikipedia and did some fleshing out.

I spent a lot of time obsessing over the descriptions on the Wikipedia page.

sangi39
05-08-2014, 02:40 PM
Oh, I just think that your climate map was a roughing-in, so to speak. As if you made a map with the suggested latitudes taken very rigidly, and painted in as bands, to use as a guide. I thought that's a great idea (and probably sufficient for any fantasy mapping needs). So I stole it :) and did something similar, but then looked at the real-world Koppen maps on Wikipedia and did some fleshing out.

Huh, how very dare you :P I do like the whole idea-sharing thing that goes on here at the Cartographers' Guild :)


I spent a lot of time obsessing over the descriptions on the Wikipedia page.

Yeah, I spend a couple of days on Wikipedia, editing my climate map as I went along, but then I got annoyed and deleted the edits :P

Pixie
05-08-2014, 08:21 PM
That's the problem with keeping the post a WIP when it comes to climate map. You spend so much time looking at it, adjusting and dealing with too many variable (rain, temperature, seasonality, high-low pressures centers, ocean currents, prevailing winds), that you end up unable to

1. explain the reasoning (if it is your map)
2. understand the reasoning and suggest improvements (if you are the lurker)

acrsome
05-13-2014, 05:17 PM
As with, I suspect, most of the larval-stage cartographers who end up here I have discovered Wilbur (all hail Waldronate). I dug up some Magellan data on Venus topography and fed it through, dealt with some annoying artifacts (thanks Redrobes), and then some more artifacts, etc. Here are a few preliminary views.

First, Thetis, Ovda, and Manatum:

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The snow line is set at about 14000 feet, by the way.

Next, here's one that shows that southern continent (Ishtar) and the south pole:

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The pole is obvious because it was missing from the Magellan data and I had to clone some in- very inexpertly- and it shows. It's that first darker ocean basin below the high mountains on the continent.


Since I can use this data to do all sorts of neat stuff with Wilbur, I think I'll use it instead of my hand-traced version from the scanned USGS maps. I'm still trying to figure out how to export images from Wilbur. Obviously, I managed to export these, but every time I try to export an equirectangular image- or actually anything not orthographic - it gets truncated at the edges. This happens even when I set the exported image's size to my map size. Grr.

Once I deal with a bunch more little artifacts I'll start exporting it to GIMP, making sea masks, etc.

acrsome
01-11-2015, 12:56 PM
Well, I've started playing with this project again, mostly puttering around learning Wilbur. I also decided to have a bash at Pixie's climate technique (http://www.cartographersguild.com/showthread.php?t=27118&highlight=climate) to see if my original thoughts jived, so I re-did my sea levels and tried to work out some better and more detailed currents:

70114

Do you have any critiques of the currents?

One problem I have is that Venus really doesn't have continental shelves. Also, I'm particularly interested in opinions on three areas:

1. The gyre from Phoebe-Imdr-Zhibek, with the Gulf Stream hitting Imdr. This is, I suppose, my equivalent of the North Atlantic. South of that is an equatorial countercurrent, and south still more is a small gyre in the southern part of that sea. The way I have them interacting seems contrived, though I looked at the 1943 map (http://en.wikipedia.org/wiki/Ocean_current#mediaviewer/File:Ocean_currents_1943_(borderless)3.png) on the Wikipedia ocean currents page and there seem to be even more dramatic currents crossing the equator in south Asia. I don't have a terrestrial model for the fact that there are a few small straits that would connect the equatorial gyre with the Beta-Ulfrun gyre. Thoughts?

2. I based the large southern-hemisphere gyre around Gula and the islands to the west of it on south Asia with all of its islands and straights, so it looks busy but I think it works. (I didn't try to map every little current in that region, just enough to fun the climate thing.) Thoughts?

3. The gyres north of Ovda and on either side of Ulfrun- am I doing that right? Or should they just be 'lobes" off of the polar currents?

And, of course, any other criticisms are not only welcome but appreciated.

Ignore the thumbnail map below- it's old, and I can't seem to figure out how to remove it.

ascanius
01-12-2015, 10:28 AM
Your map is very interesting so far. There are a few areas I would have done differently but this mostly concerns micro currents among the archapelegos. I however did notic that your polar currents need some work. For example, the ocean east of Telius, that west coast should be a warm current going south, the black current lines ( >45 degrees) for both poles are the wrong direction and should be traveling west not east. One thing that helps is to overlay your hot cold pressure systems over the ocean currents to get a better idea of how things line up, ocean currents follow the high low pressure systems of the atmosphere.

I did a quick paint over to show you what I mean.

70126

Hope that didn't confuse you.

acrsome
01-12-2015, 02:02 PM
Really? I was using this (http://en.wikipedia.org/wiki/Ocean_currents#mediaviewer/File:Corrientes-oceanicas.png) and this (http://upload.wikimedia.org/wikipedia/commons/6/67/Ocean_currents_1943_%28borderless%293.png)as sources for polar currents- they show the Antarctic circumpolar currents as being eastward at 60S, though, yes, I had to try to account for the Ishtar and Lada continents being in the way. (Are you looking at subpolar currents? These are indeed westward.)

I see what you mean about the splitting of currents into a warm poleward and cold equatorward branch, especially on that second map I linked- I'll work on that. I do have something like that around Beta, though I represented it as a very weak southbound current, but you're right I could do a better job around Tellus. Clearly I shouldn't have that northbound cold current there. Mostly, though, I have to be sure that I have the direction of the circumpolar currents correct, since that will affect a lot. Yes, on Earth that splitting occurs in the southern hemisphere and the southern split joins the 60S circumpolar current, but that circumpolar current isn't a westward countercurrent- it is eastward. If I take southern Earth as my model than the currents you changed arounf Tellus should be more like the currents you added south of Beta- eastward. Or am I missing something?

Likewise, regarding the minor gyre between Xartanga and Lada- why did you switch the direction? Are you thinking of Hadley cells?

Or, maybe I should just make both of my poles more like Earth's northern pole, with smaller current "lobes" but no true circumpolar current. Is that what you mean? I'm finding the polar currents rather frustrating. But I want to get this as "good" as I can make it before I proceed further. (Thank God that since I'm working from real data I don't have to mess around with tectonics. I might have an apoplexy.)

I'll play around in GIMP when I get home.

ascanius
01-12-2015, 06:05 PM
Really? I was using this (http://en.wikipedia.org/wiki/Ocean_currents#mediaviewer/File:Corrientes-oceanicas.png) and this (http://upload.wikimedia.org/wikipedia/commons/6/67/Ocean_currents_1943_%28borderless%293.png)as sources for polar currents- they show the Antarctic circumpolar currents as being eastward at 60S, though, yes, I had to try to account for the Ishtar and Lada continents being in the way. (Are you looking at subpolar currents? These are indeed westward.)

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.


I see what you mean about the splitting of currents into a warm poleward and cold equatorward branch, especially on that second map I linked- I'll work on that. I do have something like that around Beta, though I represented it as a very weak southbound current, but you're right I could do a better job around Tellus. Clearly I shouldn't have that northbound cold current there. Mostly, though, I have to be sure that I have the direction of the circumpolar currents correct, since that will affect a lot. Yes, on Earth that splitting occurs in the southern hemisphere and the southern split joins the 60S circumpolar current, but that circumpolar current isn't a westward countercurrent- it is eastward. If I take southern Earth as my model than the currents you changed arounf Tellus should be more like the currents you added south of Beta- eastward. Or am I missing something?

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.


Likewise, regarding the minor gyre between Xartanga and Lada- why did you switch the direction? Are you thinking of Hadley cells?

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.

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.


Or, maybe I should just make both of my poles more like Earth's northern pole, with smaller current "lobes" but no true circumpolar current. Is that what you mean? I'm finding the polar currents rather frustrating. But I want to get this as "good" as I can make it before I proceed further. (Thank God that since I'm working from real data I don't have to mess around with tectonics. I might have an apoplexy.)

check these out they might help you out . http://www.divediscover.whoi.edu/arctic/circulation.html
http://beyondpenguins.ehe.osu.edu/files/2011/07/web_arctic_currents.jpg
http://polardiscovery.whoi.edu/antarctica/images/antarctica-circulation-en.jpg


good luck

acrsome
01-12-2015, 10:07 PM
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
01-13-2015, 04:51 AM
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.

70130

ascanius
01-13-2015, 01:47 PM
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.

70130

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

acrsome
01-14-2015, 12:13 AM
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 (http://en.wikipedia.org/wiki/Ocean_current#mediaviewer/File:Corrientes-oceanicas.png)- 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 (http://upload.wikimedia.org/wikipedia/commons/6/67/Ocean_currents_1943_%28borderless%293.png). 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):

70141

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:

70142

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
01-14-2015, 01:36 AM
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
https://drive.google.com/file/d/0B6ZYAd08tZL-R3ZqQmtVbE5wSlk/view?usp=sharing

from
http://pds-geosciences.wustl.edu/mgn/mgn-v-gxdr-v1/mg_3002/gtdr/
holes filed and upscaled using a SFS algorithm on the radar mird FULL data
http://pds-geosciences.wustl.edu/mgn/mgn-v-rdrs-5-midr-full-res-v1/

acrsome
01-14-2015, 11:25 AM
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).

acrsome
01-17-2015, 11:29 AM
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? :)

70210


Other old tries:

johnvanvliet
01-17-2015, 03:03 PM
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/mgn-v-gxdr-v1/mg_3002/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

acrsome
01-17-2015, 04:04 PM
it is
cleanning up the data from here
http://pds-geosciences.wustl.edu/mgn/mgn-v-gxdr-v1/mg_3002/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:

70222

johnvanvliet
01-18-2015, 05:37 AM
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

acrsome
01-18-2015, 10:28 AM
so you are going with NORTH on the bottom of the map

Yes, so that the sun rises in the east. Mind you, I'm still going to call the top of the map "north" and the bottom "south." As I mentioned before, this is to keep to familiar conventions for any notional RPG players (http://forums.sjgames.com/showthread.php?t=121252) that may eventually have characters inhabiting this world.


as to your "sealevel" and mine

Oh, so you're doing the same project? I'd be interested to see what you've got. I'm planning to fill a lot of those more dramatic inland depressions as lakes (i't a bit of a project to figure out their elevations) but I'm going to fill some of the more shallow ones. And a few will just be depressions in desert areas, though it looks like when I use your data that the desert in Artemis won't be quite as huge.


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

Yes, I think I grok that.

I did elevations the easy way: in Wilbur I did Filter>Mathematical>Span and set it from -19250 to +25683. This sets elevations in feet with the sea level as in my map above. (I'm generally a metric guy, but from all of the North American hiking I do I'm used to thinking in feet for elevations.) This is derived by the lowest point (1.8 miles below the mean radius) and the highest point (6.71 miles above the mean radius).

acrsome
01-25-2015, 11:44 AM
Still slowly working. Here's some (very minimalist) labeling:

70356

jkat718
01-25-2015, 08:33 PM
Looks good, acr! I particularly like the coloring, both for the labels and for the terrain itself.

acrsome
01-26-2015, 10:55 AM
Looks good, acr! I particularly like the coloring, both for the labels and for the terrain itself.

The terrain is all Wilbur at this point, I'll pass the praise on to Waldronate. Well, except for the below-sea-level basins, which I have temporarily filled with that psychedelic green tint. I'm no artist. This is more an exercise in worldbuilding for me. As I slowly figure out GIMP I'll keep trying to makle it prettier, but that's after I've done the worlbuilding. I need know where it rains, for instance, before I can tint the vegetation, decide if a basin is a lake or a salt flat, etc.

Regarding the labels- I finally sat down and figured out how to text-to-path in GIMP, so I'm playing around with it a bit. For that matter, I think that I finally understand layer masks. Woop!