[WIP] Building a world from tectonics onward

[MrBragg]

Congratz on finishing the topograhy, MrBragg! I think you must be the first one to have finished a planetary-scale elevation map built with this kind of technique and detail (makes me think I should get off my lazy arse and get some progress done on my own project).

Thanks, Charerg! I guess being stubborn does actually have some advantages Would also love to see your latest map since it was one of the big inspirations for me.

1, I've done some tests lately with exoplasim runs starting with 1 meter of initial global glacial cover; it takes a bit longer for the climate to settle out, at least 50 years whereas they usually are mostly settled within 20 years otherwise, but the resulting glacial cover is a lot more accurate, as well as the global average temperature. it does make some mid-latitude areas even colder than they should be, though.

So I tried this at T42 and starting with glaciers did converge to a marginally cooler overall temperature at 300 ppm CO2 (22.4 C vs 22.9 C). Starting with <=200 ppm CO2 resulted in a snowball, though, so the hysteresis caused by starting with glaciers may constrain the accessible final temperatures somewhat.

On a somewhat related note, @worldbuilding pasta, do you have any experience running resolutions >T85? For giggles I tried everything larger and each and every one immediately crashed before the model even got going, even when using an identical input from T85 (only resolution and sra inputs changed) that worked fine.

[worldbuilding pasta]

So I tried this at T42 and starting with glaciers did converge to a marginally cooler overall temperature at 300 ppm CO2 (22.4 C vs 22.9 C). Starting with <=200 ppm CO2 resulted in a snowball, though, so the hysteresis caused by starting with glaciers may constrain the accessible final temperatures somewhat.

You might try running it first at 300 ppm for 10-20 years and then reduce co2

On a somewhat related note, @worldbuilding pasta, do you have any experience running resolutions >T85? For giggles I tried everything larger and each and every one immediately crashed before the model even got going, even when using an identical input from T85 (only resolution and sra inputs changed) that worked fine.

I haven't even done a proper T85 run yet, I wanna test it more but I've sort of paused my exoplasim work for the winter because of the energy costs here. It might be a ram limitation or something, it might need more layers, or it might be the same bug people have been having with t63 that I still have yet to investigate.

[MrBragg]

You might try running it first at 300 ppm for 10-20 years and then reduce co2

Yeah, if I were super ambitious I could try that, though my results at ~120 ppm CO2 I think are already decent enough to move forward. I've already baked my ice caps into the terrain anyway, so as long as the EPS output gets close I'm happy.

It might be a ram limitation or something, it might need more layers, or it might be the same bug people have been having with t63 that I still have yet to investigate.

Ok cool, those were my first thoughts as well. Going to 15 layers didn't affect it and the error I got was different than when I tried T63, which very clearly told me that that resolution wasn't supported. For memory, EPS at T42 doesn't seem to use all that much RAM (I have 64 GB) and I can run a T85 and a T42 simultaneously, so assuming memory usage scaled ~linearly then I'm imagine at least T106 should be able to run. Next time I run a T85 I'll pay closer attention to the memory usage during the cycles and make sure it never spikes higher than I'd expect.

I haven't even done a proper T85 run yet, I wanna test it more but I've sort of paused my exoplasim work for the winter because of the energy costs here.

If it's at all helpful, I could run some calculations for you when my computer is open, so just let me know.


EDIT: OK so I did some more digging and for T106 and T127 it looks like EPS is missing files it needs for those resolutions. For T106 for example, it starts out with the message "/home/users/.local/lib/python3.6/site-packages/exoplasim/plasim/run/most_plasim_t106_l10_p16.x...." and then crashes; for T85 and T42 this step passes almost instantly and then the model begins. It turns out that the t106_l10_p16 (resolution_levels_processors I'm guessing is the nomenclature) file isn't present in the requested directory and neither are any files associated with T127. So, unsure if this is an issue on my end or with EPS, but figured I'd post it here in case it's useful.

[Naima]

Yeah, if I were super ambitious I could try that, though my results at ~120 ppm CO2 I think are already decent enough to move forward. I've already baked my ice caps into the terrain anyway, so as long as the EPS output gets close I'm happy.





Ok cool, those were my first thoughts as well. Going to 15 layers didn't affect it and the error I got was different than when I tried T63, which very clearly told me that that resolution wasn't supported. For memory, EPS at T42 doesn't seem to use all that much RAM (I have 64 GB) and I can run a T85 and a T42 simultaneously, so assuming memory usage scaled ~linearly then I'm imagine at least T106 should be able to run. Next time I run a T85 I'll pay closer attention to the memory usage during the cycles and make sure it never spikes higher than I'd expect.




If it's at all helpful, I could run some calculations for you when my computer is open, so just let me know.


EDIT: OK so I did some more digging and for T106 and T127 it looks like EPS is missing files it needs for those resolutions. For T106 for example, it starts out with the message "/home/users/.local/lib/python3.6/site-packages/exoplasim/plasim/run/most_plasim_t106_l10_p16.x...." and then crashes; for T85 and T42 this step passes almost instantly and then the model begins. It turns out that the t106_l10_p16 (resolution_levels_processors I'm guessing is the nomenclature) file isn't present in the requested directory and neither are any files associated with T127. So, unsure if this is an issue on my end or with EPS, but figured I'd post it here in case it's useful.

What pc specs do you have?

[worldbuilding pasta]

I think it compiles the "most" files on demand for each configuration the first time you attempt to run it, so it's not that they're missing but failing to compile (or something fails before it even gets that far). I can shoot the dev a message that these resolutions still aren't working, but I think they've just been too busy to work on exoplasim for a while because there are fixes I know they've wanted to do for a while that they haven't implemented.

[worldbuilding pasta]

If it's at all helpful, I could run some calculations for you when my computer is open, so just let me know.

If you really wanted to, I'd be interested to see what happened with Earth topography (max elevation 6300 m on this file) and standard settings (300 ppm etc) at t85 with 1 m initial glacial cover run for 50-100 years, to see if it fixes some of the issues at t42

[MrBragg]

I can shoot the dev a message that these resolutions still aren't working, but I think they've just been too busy to work on exoplasim for a while because there are fixes I know they've wanted to do for a while that they haven't implemented.

Thanks!

If you really wanted to, I'd be interested to see what happened with Earth topography (max elevation 6300 m on this file) and standard settings (300 ppm etc) at t85 with 1 m initial glacial cover run for 50-100 years, to see if it fixes some of the issues at t42

Yeah sure, can start that in a few days. Quick question though: for the Image2sra script, is the max elevation the script asks for the value corresponding to fully white (255) or the highest elevation in the image, regardless of its color value? I've been assuming the former, but if it's the latter I'll make that adjustment.

[worldbuilding pasta]

You know, I think you might be right, so to be sure here's the map rescaled so the max elevation is white

[Tiluchi]

Just jumping in to say that that topography looks amazing! As Charerg said I think it's the first 100% complete planet I've seen done with Wilbur, so for that alone it's very impressive. Not sure to what extent you messed with GPlates, but you can input your finished map into GPlates by linking your continent polygons to the raster file, which might help in confirming that the geology makes sense from a tectonics perspective.

My only *tiny* nitpick is that the coastlines in general look a little more irregular than we generally see on Earth- not sure if that's just an artifact of the Wilbur processing. I always have to look at the coastlines of Africa and Australia to remind myself that very smooth coastlines are actually quite common in many areas!

[MrBragg]

Not sure to what extent you messed with GPlates, but you can input your finished map into GPlates by linking your continent polygons to the raster file, which might help in confirming that the geology makes sense from a tectonics perspective.

Thanks Tiluchi! I used gplates to work things out starting from the previous supercontinent, so features older than that were added via artistic license Even doing that much was a bear, so going back any further gives me terrible flashbacks to agonizing over plate interactions.

My only *tiny* nitpick is that the coastlines in general look a little more irregular than we generally see on Earth- not sure if that's just an artifact of the Wilbur processing. I always have to look at the coastlines of Africa and Australia to remind myself that very smooth coastlines are actually quite common in many areas!

Appreciate your feedback here. You know, I actually went back and smoothed some areas during my pass on topography, though now that I look at things again I think you might be right... Something for the to-do list, I suppose.


In any case, I've kept playing around with ExoPlaSim a bit and managed to get a T85 model with completed topography and more reasonable temperatures to complete. Since that worked, I've been trying to work on how to import the EPS outputs into the Azelor et al tutorial here so that I can correct some of the systematic errors from EPS. By 1) manually adjusting the temperature to "undo" EPS's low resolution elevation cooling and then readjusting using a high resolution heightmap and Azelor's guide and 2) a little hand-waving on the precipitation maps, I managed to convert the EPS Jan / July temperature and precipitation maps into the right color format for the tutorial; other than still being a bit warm and perhaps a bit too wet, IMO they look reasonable:

Jan / July Temperatures


Jan / July Precipitation


From there, I can run AzureWings script to generate a Koppen map which matches up quite well with the raw and interpolated / altitude corrected results from Nikolai's script. The agreement isn't perfect, but it's certainly good enough IMO to indicate that this process captures the main features. Interestingly, the AzureWings result doesn't have the same extensive regions of mid-latitude Med climates and (too) high latitude hot deserts as the results reading directly from the EPS data; not entirely sure how the Pasta scripts use the EPS data but it's interesting to see that not reproduced here.

AzureWings


Raw EPS


Interpolated / Altitude Corrected EPS (only a single year as the script doesn't like my averaged nc files)


Now that I've gotten this working, I should be able to manually alter the EPS temp / precip outputs to correct some of the systematic errors and get to a reasonable compromise climate map. Overall, not too painful, either


P.S. I haven't forgotten about doing your T85 earth calculations, worldbuildingpasta. This last T85 for me took a bit longer than I'd planned as I needed to reduce the timestep to 15 minutes to prevent crashes, so I'm just a bit behind. Yours is next on my queue though, so hopefully not too much longer!