Earth Ocean Currents
When choosing world map projections from the customary library of available layouts, the problem reduces to picking the least worst alternative. But, at least when our interest is in ocean currents, the customary library works pretty well.
Here’s why: Earth’s rotation in space — spinning on the polar axis — drives the ocean currents. So a world map that centers up a pole shows the rotational axis as a point (a line seen on end appears as a point) and shows the currents with the same (or similar) clarity of understanding as an axial view of motor.
The projection we want is an “equal azimuth,” and it looks like a circle which we may imagine to be spinning like a wheel. One pole is the point at map center, the other pole is the circle the makes the map’s edge. This is a little confusing, because now what used to be a point (the opposite pole from the one we put at map center) is now a circle within which is shown the whole surface of the earth. But that’s just the trick of equal azimuth– it gives a point (something of zero dimension) a size. The scale at map edge is infinite, but let’s not bog down. Besides, we may reverse our choice of pole for map-center and only think halfway out, then switch maps. Of course that defeats the purpose of using a world map, getting to see it all at once.
So give it a try. Work up to that outer circle slowly. Remember, it’s the patterns made by the ocean’s currents that we are contemplating, and earth’s rotation is the ocean’s motor.
Here we see SURFACE, MID-LEVEL, and BASEMENT CURRENTS in Red, Green and Blue respectively. Thanks National Geographic, for showing us how they go. (NG used an elliptical map centered on the Equator, and mislabeled 10 degrees south latitude as Equator, but hey, mistakes happen. Forgive.) I merely put them in equal azimuth projection, 10 degree graticles.
SEASONAL REVERSABLE CURRENTS (culled from several sources) are in Yellow.
LAND is Grey, with land and ICE 10,000 feet and more above sea level in White.
Earth's Ocean Currents with South Pole at Center
My, how Antarctica’s two great gulfs play with the currents! There the mid-level flow drops to basement level, but let’s look at things from the opposite side of the solar system:
Earth's Ocean Currents with North Pole at Center
What’s that you say? A little hard to follow things — especially the play of Antarctica’s gulfs — at map edge? And what, around the periphery, are those trails of white dots?
Here’s what’s going on: On world maps, we traditionally want our continental shapes fair and regular, and let the smeary parts be the water. The top map’s edge is the North Pole, which is water, so it’s a little easier to spot the landmarks. The bottom map’s edge is the South Pole, so Antarctica gets smeared. But Antarctica has topographic structure; it, as all continents (islands too) is made up of watersheds, valleys separated by ridges. The White Dots are Antarctica’s RIDGES. nd with constant-scale natural boundary mapping, we can use these ridges to form the edge of another map that, even though it cannot present Antarctica as a unified, conformal shape, it can present Antarctica’s constituent watersheds as unified, conformal shapes:
A Constant-Scale Natural Boundary Map of Earth edged by Antarctic Valleys
Allright so far, you perhaps say. But what are the several shades of Grey? And, since Antarctica is covered with ice, what valleys do we see on this map, rock valleys or ice valleys?
Answers: Shades of grey are various categories of rock (in relation to sea level), and the valleys shown are rock. And, though you didn’t ask — yes, the map does fold up, to highly condensed globular object. Here’s a little poster with specifics.
Earth, from Antarctic Valleys' Point of View
Sorry for the low resolution on these images.
May 13, 2009 at 2:13 pm
Wow, this is a most interesting article. These currents will be there for many years to come. It just makes me realize how far we have come since the middle ages. We now know that if we are a water molecule off the coast of florida, there are a multitude of currents we can follow to get to the North Pole to meet Santa!
Thanks. ~Peter Luu
May 13, 2009 at 2:24 pm
Merry Christmas Mr. Luu.
December 16, 2009 at 11:26 am
These world ocean current maps are fantastically informative. The South Pole map reminds me of the map of the clipper route from Australia to Britain around Antarctica provided by Geoffrey Blainey in his book The Tyranny of Distance. I’m hoping to float large polymer bags of fresh water through the currents of the ocean, as Dr Ian Edmonds has suggested in his article Northern River Water for Australian Cities? and as Terry Spragg describes at waterbag.com. We eventually want transport routes that can be fuelled by ocean currents rather than fossil fuels.
December 16, 2009 at 1:29 pm
Robert, I’m happy to be of help. If you use any of the current maps please don’t neglect to credit my website. Your project is fascinating. Please keep me informed. I’m presently working on an animated overlay (for one of the current maps) of cloud movements during a six-week-period of the 2009 hurricane season. Regards.
December 17, 2009 at 9:08 am
Thanks Chuck. Here is what I have posted at http://www.oceanclimate.org/forum/new-forum-topic-ocean-currents
Re: New forum topic for ocean currents!
Wed, 12/16/2009 – 6:16am — Robert Tulip
The currents of the world ocean are like the arteries and veins of our body, circulating nutrient to keep the whole organism healthy. The ocean is 361 million square kilometres in size, 71% of the earth surface. As we consider the crowding of our planet, people will naturally look more to how we can live on the ocean in a sustainable way.
A fine map of the world ocean currents centred on Antarctica, giving an extremely different perspective on our planet from usual views, is at http://rightbasicbuilding.files.wordpress.com/2009/03/north-edged-equal-...
One day, we will manage the world’s climate, food and fuel security by understanding and using the ocean as the driver of a single integrated system of planetary ecology.
Robert Tulip
rtulip.net
December 17, 2009 at 9:13 am
Link actually works in the original post! it is
http://rightbasicbuilding.files.wordpress.com/2009/03/north-edged-equal-azimuth.png?w=450&h=465
December 17, 2009 at 9:21 am
Hi Chuck
I would be interested if you could say what the depth, speed, nutrient load and temperature are of the red, green and blue circumpolar currents around Antarctica.
Hope this is not too much trouble.
Thanks
Robert
(Please feel free to combine the two previous posts to correct the link in the first post)
December 17, 2009 at 10:44 am
Robert, Those would indeed be interesting things to know, but I am merely a mapmaker, with elaborate skill only in how the surface of the object is unfolded. All the info, like these current lines, I put on the maps is just stuff I’ve gathered from other sources. You’ll have to hunt down the oceanography experts for that sort of detail. Sorry.
January 7, 2010 at 5:39 pm
These are very interesting and useful views of the ocean currents, as they help to show that we have one ocean with currents that flow through several ocean basins. However, it is incorrect to say that Earth’s rotation drives these currents. The ocean surface currents are primarily wind driven, while deeper currents flow in response to density differences. Additionally, there are oscillating tidal currents which vary in strength around the globe. Earth’s rotation *modifies* these currents by causing apparent deflections to the right in the northern hemisphere, and to the left in the southern hemisphere. Regarding the surface currents, there really ought to be a branch northward along the coast of Japan, and then eastward into the central Pacific to depict the Kuroshio Current, one of the major western boundary currents. See http://oceanmotion.org/html/background/wind-driven-surface.htm
January 7, 2010 at 7:28 pm
The mapmaker stands corrected by a professor of oceanography.
As for the Kuroshio Current, I’ve another version of these maps showing many more surface “boundary” currents (including Kuroshio). These maps (with my addition of seasonally reversing currents shown in yellow) depict the major currents as National Geographic had them. I presume because they were seeking to present global patterns amongst three levels of currents, and used that rationale to exclude major surface currents that had only localized sway. NG might have over-simplified things in order not to overwhelm a general audience. See my comment under Watersheds “M” here
January 7, 2010 at 8:50 pm
Hello, thank you Emil for your comment. I agree Chuck has provided very interesting and useful views, especially by placing Antarctica at the centre of the world ocean. Another apparent discrepancy between the map at your linked site and Chuck’s map is that Chuck presents a north moving surface current in the Pacific Ocean to the east of New Zealand, but this is not apparent in your map, unless the difference is simply an artifact caused by the different projections.
January 7, 2010 at 9:01 pm
Robert, the north-moving surface current to the east of New Zealand, not apparent on the Emil-link map, is taken from the National Geo map. It is not an artifact of the projection, so a discrepancy. Any experts out there who’ll straighten this out?
January 8, 2010 at 1:11 pm
There is a surface current which flows northward along the east coast of New Zealand (see http://www.teara.govt.nz/en/ocean-currents-and-tides/1/1 ). It does not appear on the map which NASA adapted from the American Meteorological Society, probably because that map is simply an attempt to show the major ocean currents and the gyres in the ocean basins. The flow along New Zealand could be viewed as contributing to the southern portion of the gyre which flows around the southern Pacific Ocean.
January 27, 2010 at 9:55 pm
hi, just wondering, if there is more earthquakes in indonisia and the the plate rises more and restricts the warm flow through there, will all the currents stop, and cause a worldwide drought. like what happened to the egyptians.
January 27, 2010 at 11:42 pm
Well, I’m no expert on anything but mapping, but I doubt anything like what happened to the Egyptians (surely you mean the ancient Egyptians?) is in the cards for the whole world. There’ll be more earthquakes in Indonesia, as well as everywhere else, I think everyone but nutjobs will agree with that, but in my opinion you really don’t have to worry about “the plate rising more and restricting . . . [ocean current] flow through there.” My most informed sources tell me (they’re a minority view, but that’s usually the case with the arrow of knowledge) that the disposition of continents is pretty much the same now and into the future as it’s been for a good long time, say the last billion years or so. Best steer I can give you is to look beyond the plate tectonics paradigm for some more overarching theory — see what you can come up with. Sea-floor spreading is really happening, but the other end of the cycle — trench subduction and the so-called Wilson Cycle — are being contradicted by experiment. Drop in here http://www.ncgt.org/ and look around.
And in any event the currents ain’t gonna stop. If they get blocked up somewhere they’ll just reorganize. Me, I’m a lot more worried about the antarctic ice sheet suffering a nudge toward the coast. If it ever gets started moving, it’s not stopping ’til it’s in the sea.