Nikolai Lofving Hersfeldt
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Earth with mirrored hemispheres
🕑 Added 2023-12-06 22:43:21 +0000 UTCSo I decided to put aside my somewhat troublesome runs with varying stars or insolation for the moment and instead do some runs with both obliquity and eccentricity. Trouble is, this might have different effects on each hemisphere--enhancing summer and winter in one and damping them in the other--and that might be hard to pick out on the regular earth map where the hemispheres have quite different topography. My somewhat hacky and cursed solution is to just flip the northern hemisphere to give equivalent topography across hemispheres. This is just a test run of that map run to balance with all the same parameters as baseline (23.5 degrees obliquity, zero eccentricity, 300 ppm CO2) to check if it made any big differences. The greater land area did end up cooling the planet by about 3 C, but otherwise it doesn't seem to have made too big a change from the baseline hemisphere; there is perhaps a stronger monsoon pattern around the now encircled Indian ocean, but if anything that's just bringing it closer to real Earth. The hemisphere climate maps aren't perfectly mirrored if you look closely, but that's probably just down to a bit of random noise the 10-year sample I make these maps from wasn't big enough to filter out and possibly something about the way the model calendar is set up and monthly averages are sampled slightly biasing the results; it's still close enough I think any differences induced by the obliquity+eccentricity combo should be obvious.
Anyway, the plan right now is to run all combinations of 23.5, 45, and 90 degrees obliquity with 0.1, 0.3, and 0.5 eccentricity. For now, I'll do them all with periapsis coinciding with a solstice (can't remember if I set it right for north or south summer solstice, I'll be able to tell from the outputs pretty easily).
Comments
Nikolai Lofving Hersfeldt
Northern Europe is already too cold in the regular baseline because it's one of the areas with the strongest heating by ocean currents, which ExoPlaSim doesn't properly model, so the extra cooling here isn't actually that big a shift.
Thanasis Kinias
There are some quite interesting effects here. Just that small amount of cooling is affecting places like Europe pretty dramatically—my eyes are drawn to the British tundra and the Dsb (dry-summer subarctic) Netherlands.
