Rough draft of my world's ocean currents.

(Excuse the mess, as this is just a rough draft I drew up in CC3+. If it needs to be tidied up, just let me know. Bright red and dark blue arrows indicate wind direction.) I was marking the ocean currents for my fantasy world and ran into some troublesome areas. The areas that gave me the most trouble are circled in yellow. I'm not entirely sure they're behaving accurately.

(Yellow circle on the right): There's very little water above 30 degrees N, so how would these currents behave? What I have marked is the best way I could get it to work, but I'm not entirely sure if that's at all accurate.

For the right, how would the colder current behave given the landmasses? Would it flow south along the coast, or would it flow eastward along the coast until it encountered the polar cell?

Are there any other mistakes I made or other factors I failed to consider? This is my first time trying my hand at scientifically accurate worldbuilding, so any and all constructive criticism is welcomed and desired. This is also my first post on here, so if I goofed at all, please be merciful lol. Thanks!

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    $\begingroup$ We need some more detail, if you don't mind. Currents are horrifically complex and depend on a ton of variables. Could you tell us about your world's moons (tidal effects) and its sun and/or seasons (temperature variation)? And can you tell us the rotational speed of the planet and its size? Could you also provide a second map roughly showing ocean depths? As you can imagine, the Sea is a huge pump driven by tidal motion, temperature variation, planetary rotation, wind/weather, an a lot of other nasty effects. But if you get us the basics, we can help you out. $\endgroup$
    – JBH
    Jun 22, 2020 at 5:14
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    $\begingroup$ Everything is pretty much earthlike, from tidal effects to seasons to rotation to axial tilt, etc. As for the depth, I'm mainly concerned with surface currents. I'm not looking to get too in-depth - just enough to get an idea for climate zones. $\endgroup$ Jun 22, 2020 at 5:21
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    $\begingroup$ P.S. There are currents caused by density-and-temperature gradients; currents caused by consistent wind direction, currents caused by tidal motion, and currents caused by drainage from precipitation. $\endgroup$ Jun 22, 2020 at 10:48
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    $\begingroup$ Lol. Surface cold currents would still originate in the polar regions and warm up by the time they reach the equator. Especially if you take into account any shallow bathymetry. If you look at any google image result for surface ocean currents you will see examples of what I mean. See here $\endgroup$ Jun 23, 2020 at 13:41
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    $\begingroup$ Generally in the S. Hemisphere, EarthLike rotation means that, warm surface currents flow south from the equator on the eastern side of the continents and cold currents flow north on the western side. Generally in the N. Hemisphere, warm surface currents flow north on the eastern side and cold currents flow south in the western side. N. Hemisphere is a bit tricky to generalise as Earth is mostly landmass in the N, and complicated bathymetry and coastal shape allows for exceptions. $\endgroup$ Jun 23, 2020 at 13:42

2 Answers 2


Assuming that the straight red and blue lines are your 30 degree markers... I've made some notes. Please take with pinch of salt and don't hesitate to point out any inaccuracies.

Think of your southern region of interest as India and the far east, your northern area of interest as Europe and Scandinavia (with some adjustments).

You have a strong circumpolar antarctic current in the south. Cold water currents flowing without hitting landmass. This is similar to real-life so you can use, South America, South Africa, Australia and New Zealand as examples of how cureents will flow.

Your southern right hand yellow area in question has no real connection to cold water sources. So your cold currents in it make no real sense, regardless of "rule" that they should...they still need a cold source. I believe it will be a slowish warm current gyre, circulating the water trapped in the area by the landmasses. The main entry/exit point for fresh water will be in the southwest, where water from the cold current hitting the western edge of your southern continent with flow northwards (similar to the Peru and w. Australian currents). Some water may escape through the eastern straits. Think warm waters interchanging through the Malacca Strait, Sunda Strait and Timor Sea etc.

Your northern left hand yellow area in question is trickier. You should also have a circumpolar current in the north (earth doesnt have this so it's not directly relatable). Cold water will be flowing east to west, reflecting off landmasses on the eastern edges, it doesn't have as much space to spread out so will probably not be as established and strong as the southern current. You should also have a warm current flowing northwards from your right hand side of the map (far east equavilant) towards your left hand side of the map. This warm current doesn't look to be very strong so it won't act in a similar manner to the Kuroshio or Gulf stream currents.

The Kuroshio, I'm not too familiar with, but it has a long fetch and carries alot of moisture that hits the cold n. american landmass bringing snow and lots of rain. The gulf stream brings warm water and air alot further north than would be expected bringing more temperate climates to Europe than would otherwise be expected.

Depending on the strength of your equavilent warm north current, you can either have something similar to what I drawn below (I'm not confident about it being so cold), or you can have a stronger warm current that hits the western edge of your northern islands and flows back south, similar to the gulf stream dynamics although not as strong. This would probably still have some input from the cold current. And would still be fairly cool when flowing south just below your circled area.

enter image description here

Orange are warm surface currents and green are cold surface currents.

  • $\begingroup$ Thank you! That makes a lot of sense. Certainly works better than what I had modeled. For the eastern regions, what would you say the climatological consequence would be? Would the climate be analogous to the regions you mentioned? $\endgroup$ Jun 24, 2020 at 4:59
  • $\begingroup$ @NathanielLeinart it's hard to say regarding climate. The earth equivalent of your SE region of interest is dominated by the monsoons and typhoons. Monsoons in turn are largely driven by large scale topography changes and the atmospheric circulation system. I.e. the Himalaya's would play a large part in that regions climate. Typhoons originate in the warm Pacific ocean and migrate roughly westwards toward the land. I suggest you investigate these two features(monsoons and typhoons) for more detail on how your world be effected. $\endgroup$ Jun 24, 2020 at 20:53

There are other factors that affect ocean currents Salinity, ocean depth, the rate of depth change that causes upwellings.


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