Chord - Yet Another tectonics/winds/climate/etc World Map Project

[AzureWings]

So I've been fiddling with more temperature-generation-script ideas when I've been up to map-related things recently, but I wanted to resume trying to get Chord right enough to continue with. I set up simulation in GPlates up to 140mya from the present state, and although I'll admit I modeled some things rather roughly (I'm a bit embarrassed, but I started running out of patience with the plate movements ) it gave me a clearer idea of an overall tectonic history/sequence of events to base the current state on.

At ~140mya the major landmasses of Chord are in two supercontinents, one roughly centered on the south pole consisting of what are now F, O, E, V, and A and one roughly on the northern pole consisting of S, M, and C (although F+O+E and V+A are already starting to rift apart). At about this point F+O+E also breaks off a big chunk of oceanic crust from the plate also containing the landmass S - the end result of M+C and F+O+E pulling it in opposite directions. M got the continental crust along with oceanic on the other side (hence now S+M+C).

By 100mya F+O+E and V+A are definitely separate, and F+O continues to be pulled towards M+C+S. E breaks off at this point, although it is moving very slowly compared to F+O (or indeed most of the other landmasses - the plate E is on doesn't really get going too quickly at any point) and it would be probably more accurate to say F+O are broken off of E, even though they have more land area to them. Oceanic crust attached to C+S also starts to get pulled under V+A, and the former will start rifting from M soon as a result. Not too long after this point oceanic crust off the A side of V+A gets broken off by M as well (the 'B' oceanic plate in the image below).

Close to 60mya S rifts away from C under the influence of M; it has a lot of oceanic crust attached to it relative to continental crust which is getting tugged back under M.

Around 40-30mya, F breaks off of O, being subducted under M while O, the slab pull that was causing the F+O versus V+A rifting now only acting on F, begins to have all that oceanic crust that was formed during that long period start to get pulled under V+A again. This is also close to the point where that subduction virus spreads into the M/C ocean and M starts to get pulled back towards C. The very most recent major tectonic event I modeled around ~25mya was the V-A rift, with V getting subducted under E. A doesn't seem to be undergoing any subduction at the moment is is probably moving slower (although at least one plate (O) is being pulled under it).

Realizing I hadn't really modeled oceanic plates all that specifically though, I thought it might be beneficial to throw out a lot of the plate boundaries I'd drawn originally and just mark down what I was more sure about given that history. The result is below (I changed the color scheme to be more along the lines of what you used Charerg - red is divergent, blue is convergent, green is transform and yellow is "I have no clue"). I didn't even draw in some of the boundaries, where I felt really vague about where they should be. Also, where there are convergent boundaries in water I haven't drawn in any formed land, but I will when I draw in more finalized coastlines and islands and so on (such as the tails of V and A where O is pulled under them, like you pointed out Charerg earlier).



There are probably numerous issues in this version too that I haven't even noticed, but there are a few specific points I wanted to ask about:

- What makes sense for plate 'B' (oceanic crust originally attached to A broken off by M)? My thinking was that it was more heavily under the influence of O since M fell under C's influence and O broke from F, but I don't know if this is reasonable. I also don't know how it would be likely to interact with plate A which is now separate from V and also isn't being influenced strongly by M currently. At first I thought it would be pulled back under A, but had the thought that it seemed like that pattern was coming up a lot - oceanic crust formed by rifting, broken off by subduction with other landmass, then pulled back under the original landmass as soon as the situation changes.
- It seems to make sense that that central ocean would be a big oceanic plate, but with the old S-attached oceanic crust involved it looks like a much different situation, and I'm not sure 1) what its border with S would be likely to look like and 2) what its border with the oceanic plate 'T' formerly attached to S (a long time ago) would be doing. It being pulled under the M+F+S group on that side will probably add more livable land area to the present-day S vicinity which is a conceit I found neat all along, though.

[AzureWings]

Decided to get back on this project after some time procrastinating on putting together elevations and finalizing what felt like a decent landmass layout. I think I'm somewhat satisfied with the tectonics I have now myself, even if they're not quite spot on, so I'm moving on to further steps.

These are the elevations and currents - the lower elevation categories are defined in somewhat rough, broad strokes though. I tried to base the distribution of most of the elevations off of Earth - one might even be able to tell what specific regions I referenced for relative elevations for different parts of Chord . It also displays the landmasses in the shapes I finally ended up settling on; I took a result based on all the tectonic discussion but realized it was somewhat not-quite-right looking on a gut level - I'd been following outlines a bit too closely for the actual coastlines, so I perturbed things a bit and added some smaller land protrusions in various places to make it feel better to my eye.

Either way, the map also shows the currents, of which the part I was most unsure about was the polar regions near and above ±60°. I noticed that the polar easterlies don't seem to make a big impact on the most-southerly coasts of Antarctica on Earth, but since the oceans near Chord's north-polar continent do run up around 75° in some places it looked like the east-to-west polar currents made sense in some areas of it.



I also went on to lay out something that I think might make sense for the pressures. I kind of assumed that barring an intervening landmass the polar low-pressure region would encompass the whole pole and drew it like so in the south.

January/Northern-hemisphere cold season:


July/Northern-hemisphere hot season:

[AzureWings]

All right, back where I started this thread, with winds! (Which I still feel really uncertain about overall).

January:


July:


When drawing the winds I keep feeling the ITCZ low zones look like they should be tugging the equatorial tradewinds north/south of the equator a bit. Is it because I left too much of those lows over the ocean, something else, or does it actually make sense for that to happen?

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Bonus: I'm still going to go through this by hand but here's what my current attempt at automated temperature generation makes for Chord from just the elevation map:

January:


July:


Obviously still has some issues but I think it's improving (although the generator took about 30 minutes to run for this...)! I'm especially disappointed it didn't seem to catch the temperature inversion that I'd imagine would occur in that low spot in the western part of north-polar continent though.

[AzureWings]

Here are my hand-done temperature layouts for Chord (although I occasionally took a suggestion or two from my generated version):

January


July


Overall I'm feeling relatively good about these. I wasn't sure if any single landmasses were really substantial enough to be likely to result in the darkest-red temperature category, and even with just the red I wasn't 100% sure on my placement, so if anyone has observations that would suggest changes for those especially it'd be appreciated. Working on this I realized my mental intuitions for what parts of what continents were going to have what sort of temperatures was a bit off in some areas, such as the northern and southern coastlines of the southern continents (the northern coasts were warmer than I'd been assuming while the southern were colder). Illustrative of some geographic biases, I guess .

[AzureWings]

So, about half a year later I've finally dragged my way to getting through a draft of the precipitations. Definitely I need to rethink my approach for the future, as this ended up becoming quite tedious - probably was a big mistake to try to lay down one "color"/category of precipitation at a time for the whole world, then the next, etc. I'd probably have been a lot more engaged if I'd focused on one region at a time for all the categories and then moved on to the next.

Not feeling quite as solid on these as the temperatures, although I've got names to refer to the continents by now.

"July" precipitations


"January" precipitations


I'm not so sure how good my notion was in the "July" map was that the ITCZ might be partially deflected by the gigantic mountain range in SE Myrichor, as I drew the tropical rainfall zone swerving a bit more south than normal for the northern-hemisphere summer where it runs into them. I tried to reference Earth often but often fell into the trap of comparing specific regions of Chord to specific regions of Earth that they had superficial similarities to but might have been at significantly different latitudes because my perceptions were often a bit off.

Some feedback on anything that seems to be a glaring error would be appreciated.