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I've been working on a constructed world which started out as the home of an alien race from a sci-fi story I'm writing but just became a pure world building project.

As you can see from the map it has one major continent, one minor continent, and several islands. The poles are nothing but water and ice caps.

I was using artifexian's video as a guide to mapping out ocean currents but eventually, I got confused. Here you can see how far I got before giving up as well as a blank map. Thanks for the help.a map of the planet with lines illustrating the ocean currents

Could someone explain what would be a realistic pattern of surface ocean currents and upwelling for this continental configuration? Thanks!

A blank map of the planet.

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    $\begingroup$ Welcome to worldbuilding. If you want to have help from us to clear your confusion, you should also explain what confuses you. Else it looks like you are just dropping a map and ask us to do all the work for you. Please take the tour and visit the help center to understand how to ask a good question. $\endgroup$ – L.Dutch - Reinstate Monica Dec 7 '18 at 11:28
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    $\begingroup$ I am confused by your question. Ehat is the specific problem you are trying to solve there? $\endgroup$ – Renan Dec 7 '18 at 11:53
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    $\begingroup$ OP wants to know some realistic ocean currents for a world of given continental configuration? Seems like a fairly well-bounded question? There are tricky hypothetical aspects as we don't have great reasons why Earth has 3 hadley cells rather than 2 or 4 (thus knock on effects on plausible ocean currents). Plus the actual details of ocean currents are strongly controlled by ocean ridges and seafloor topography which we can't see here... $\endgroup$ – Mark_Anderson Dec 7 '18 at 15:45
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    $\begingroup$ Basically I'm saying I have a relevant PhD and the question has a interesting answers. More info from OP would be helpful, but I could answer as-is. $\endgroup$ – Mark_Anderson Dec 7 '18 at 15:48
  • $\begingroup$ @Mark_Anderson since you understand the question better than some of us, is there any edit you can make to clarify it? I'll go ahead and reopen so you can answer, but I'm really hoping you can help us improve the question too. Thanks. $\endgroup$ – Monica Cellio Dec 9 '18 at 4:12
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Currents are complicated - start from the basics

It looks like you've already got the basics down. Assuming your world has similar prevailing wind currents (i.e. three circulation cells in each atmosphere, spins the same direction, and has a similar temperature gradient), you're wise to start with the equatorial currents. These transport large amounts of water along the equator. In the middle of the deep and powerful equatorial current, there's the shallower and weaker equatorial countercurrent that flows backwards along the equator. So far, so good - although it looks like the turnaround for the south equatorial countercurrent has the arrow on the wrong end.

When this equatorial current collides with landmasses, it splits and travels to the north and the south - you've also got this covered pretty well. However, because the warm water is moving toward the west, the boundary currents running along the east coast of continents will be warm, while the boundary currents running along the west coast of continents will be cool. Check out the map of Earth below to get a sense of this:

Earth's global currents, courtesy of Wikipedia, Shadowxfox, and Popadius

Note that the blue currents (the cold ones) are generally off the west coasts of continents (which is, confusingly, the east side of the ocean) and the red currents (the warm ones) are off the east coasts of the continents. Also note that red currents always point away from the equator, and blue currents always point towards it. This also answers your question about upwelling - upwelling happens largely in cold-water currents on the west coast of continents (think Peru and West Australia).

With that, you should be able to fill in the warm and cool currents on your map. There will be a cold current traveling toward the equator the left side of your main, middle continent and (probably) the left side of your smaller Australia-looking continent.

This looks like the step where you got confused - your red arrow traveling down the southwest corner of the main continent should be blue, and pointed in the other direction (towards the equator). Remember that the main water flow at the equator is to the west, so we'd be drawing water up from the south pole to keep it going.

Now that we've got three sides to our gyres, go ahead and fill in the fourth one by connecting the head of the red current to the tail of the blue one. Now we can see another point that may have been causing some confusion - the south circumpolar current is going the wrong way! It's not impossible that this would occur, but you'd have some crazy waves and some very stormy seas where they collide, and you'd need another massive energy source (giant, angry penguin?) to explain why it's going the opposite direction.

It looks like we can expect four major gyres on your planet. Downwelling will happen in the center of these gyres, as Ekman transport moves water slowly toward the center, and water will upwell on the west coasts of the continents as detailed above.

Other recommendations

Spend some (read: a lot of, because they're beautiful) time looking at currents on Earth and how they react when running into landmasses. There's a fantastic interactive map at earth.nullschool.com which you can explore, and NASA's Ocean Eddies provides some high-resolution detail for more specific things.

I'd also recommend rotating your map projection - while it'll probably be useful for the rest of your story to have a continent-centric map, designing ocean currents will be easier if you center it on your ocean. Consider something like the Heezen-Tharp map, by brilliant oceanographer Marie Tharp:

Heezen-Tharp map, showing seafloor

Or better yet, something like the Spilhaus projection:

The Spilhaus projection, showing the connectedness of the world ocean

Actually, I went ahead and mocked up what it would look like for you because it helped me figure out the rest of the question above:

Mockup of rotated map projection

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    $\begingroup$ This answer, gives a really good, not too technical explanation of how this all works. It focuses on world design and not proving how smart he is and finally, it really helps the op. This is super excellent. $\endgroup$ – James Dec 19 '18 at 15:36
  • $\begingroup$ This covers most of it. Only things I would add is that nutrient rich upwelling normally occurs in deeper water near continental shelf edges and provide excellent fishing spots. Oceans located on continental shelfs tend to be warmer and silt laden. If you want to direct a current in a particular direction that might not be in the predictable manner, use underwater topography (bathymetry) to your benefit eg The somewhat "diagonal" Gulf Current in the Atlantic that brings warmer conditions to Europe is affected by the islands around Barbados and Florida etc. $\endgroup$ – EveryBitHelps Dec 21 '18 at 13:49
  • $\begingroup$ Think of it like directing water from a hosepipe by using your finger. More/less coverage of the pipe results in a different angled spray. Faster/weaker current conditions when passing through this florida region results in slight variations in overall current direction/speed in the end current, affecting Europe's climate. $\endgroup$ – EveryBitHelps Dec 21 '18 at 13:50

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