Oceanic Segment IV: Upwelling

To round out the whole ‘the ocean moves in orderly ways’ thing, I thought I would post something about upwelling. After this, we’ll have to put it all together (plus some!) to synegise everything into the Thermohaline Circulation System (AKA the Global Oceanic Conveyor Belt) next week.
But for now, upwelling.
And this ain’t just a verb applying to your tears whenever somebody accosts your intelligence with the ‘trickle down’ theory!
So the ocean is not just a big puddle. It has surface waters, bottom waters, warm water, cold water, dense water, un dense (???) water. The ocean is like us spoiled western children of the age of indulgence and ease- as apparently EB White said “everything in life is somewhere else, and you get there in a car.” To bottom waters, somewhere else is up, and the car is upwelling.
Bottom waters tend to be dense, cold, low in oxygen, high in nutrients. Imagine what would happen if something made these waters reach the surface: nutrients and light equals algal blooms!!
But how does dense, cold water (both factors make this water sink below the warmer, less-dense surface waters) get to the surface? It is like Cinderella under the weight of all those stepsisters- she gots so much to give but no way to gives it!

Schematic Diagram: Poor bottom waters (front) want to go to the ball but the evil stepmother Physical Laws (center), distant sunlight (in yellow, left) and conniving density gradients (right) have conspired to keep her in dim servitude below the stairs.

Ecco upwelling, as Nietzsche would say (exclaim, really)! And ecco physical processes such as the Eckman Spiral.
I like the Eckman Spiral so very much that I think we might just go so far as to pretend that all upwelling is a result of its awesomeness, although this is not true!

Remember that in the Eckman Spiral wind makes the bulk mass of water it flows over move at right angles to its direction of travel (right angles to the right and left in the Northern and Southern Hemispheres, respectively). So a wind from the north along the coast of California makes the water move away from the shore. When this happens, and really it only happens to the ‘pretty shallow’ waters, water must come from somewhere to replace it. It comes from deep water offshore, water deep enough that the wind does not direct it. So a north wind (cold enough for my liking by itself) makes all the warm (a very relative term here!) surface water go out to sea, and cold new water upwell to the shallows off the beach (making life super cold!).

Is this a good thing?

It is good if you are an algal cell. All of a sudden you have wonderful nutrients from those nutrient rich deep waters. You got sunshine, nutrients, and not a care in the world. Especially if this happens in spring, algaes fall in love (a deeply promiscuous love to be sure) and blooms occur. You might have been diving in the spring pea soup of algal blooms in the kelp forests off California?

But pretty soon, the worries start knocking. Sometimes it is a whale or microscopic grazers, sometimes lack of oxygen.

Upwelling is one of the fundamental processes that sustains the blooms of algal productivity of the Southern Oceans during spring, making whales (who have come a long ass way to eat) happy as they eat the microscopic grazers (krill) that are eating the algae. Without this the whales would be looking even worse than they are.

Blooms can mean bad things though, which is sad.

When algae bloom in the presence of light and nutrients, they comport themselves like Republicans during a bull market. Tomorrow is an abstract, and therefore non-binding, concept that only exists as something to trade in for greater profits today. Think Reagan. Think Clinton. Think Bushes. Think Algae.

They might go forth and multiply until the resources are all used up and then die. Or they might get hit by disease first, as high density populations are prone to epidemics. Or they might just suffocate themselves- life in some ways is exactly the same in water as on land; metabolism generally requires oxygen, and oxygen can be in very finite supply. One of the problems with all of this is that one way or another (through direct depletion of oxygen, or indirectly through depletion of oxygen while the dead bloom decomposes), oxygen dissolved in the water can drop. Which means that nobody living in the nearby water can breathe, so they die. Which is a major bust.

So upwelling can be bad too, but only indirectly, and who would judge it for that?


~ by maoctopus on December 7, 2010.

One Response to “Oceanic Segment IV: Upwelling”

  1. That explains why wind in the Fall also happens around really freakin’ cold water that also happens to crazy gross red tide all at the same time… Nice nice. A little difficult to follow (perhaps another draft may have smoothed out the edges) but still super cool.

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