The Pacemaker of the Chandler Wobble

Abstract: The Chandler Wobble is one of the largest circumannual periodic or quasi-periodic variations in the earth's orientation.  After over a century of searching for its forcing, it was found to be caused by atmospheric circulation and induced ocean circulation and pressure.  The question of why there should be such forcing from the atmosphere has remained open. I suggest that variations in earth-sun distance cause this forcing to the atmosphere and thence the ocean.  Analysis of earth-sun distance, earth's orientation, and atmospheric winds shows a coherent relationship between the atmosphere and earth orientation at just those periods expected from earth-sun distance variation.  As this is a general mechanism, it can be used in examining regular climatic variations on a wide range of periods and for climate parameters other than the earth's orientation.

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That is the abstract for the paper I link to below.  It's not a peer-reviewed paper in the sense of being in a peer-reviewed journal.   But it has been reviewed by an expert in the field (William P. O'Connor), who was quite favorable.

I am posting the idea and paper here.  Long past time for the ideas to be discussed.  If they're shredded in the blogosphere, so be it.  I have quite a bit more than what I've put in the document. Over the next few days and weeks, I'll post more of those additional materials as well.

The Pacemaker of the Chandler Wobble, Grumbine 2014

AABW in the news!

It only took 25 years, but my thesis topic is now becoming newsworthy!  Gluttons for punishment can see at least the abstract at A model of the formation of high-salinity shelf water on polar continental shelves.  Which is aimed at one of the important ingredients for AABW (Antarctic Bottom Water).

I've been reluctant to blog about the topic because it is, after all, my baby and I'm sorely tempted to post at excruciating length and detail.  (Not that there aren't other people who have studied the topic before or since, but I'm one of the people who has.)

I'll take this note as opportunity to get in to some detail about the weirdness that is sea water, and come to the climate change, carbon dioxide burial, and heat burial, aspects later.  The story of AABW turns on some odd facts about how sea water behaves in Antarctic conditions.  Not least, it can go below freezing.

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Building a climate model

Last Friday I mentioned a model, and will be getting to how it connects to Saturn's hurricane.  But some interesting to you, I hope, byways occurred to me. 

Let's start with the notion of a model.  Sometimes people quote sarcastically George Box's observation "All models are wrong.  Some models are useful."  Often they omit the second half.  And often they ignore the fact, well-known to any observationalist, that the same applies to observations. 

Models are idealizations of the real thing.  As an idealization, they don't represent reality fully.  This is mandatory for my kind of models.  Suppose you want to model ice ages, which span 100,000s of years.  A complete, non-idealized, model would be exactly an entire duplicate Earth, in a duplicate solar system, that we could control for our experiments.  Which might be fine as far as that goes, but would also mean we'd have to wait 100,000 years to see the result of 1 ice age experiment.  'Real time' modeling doesn't cut it for climate.  Or for weather -- if it takes 24 hours to make a 24 hour forecast of the weather, you really can't get much use from the model.

Being able to get an approximate answer much faster than real time is crucial to weather and climate modeling.  I backed in to this by way of some computer sciency experimentation I was doing.  Consider the important element being how much faster that you can get an answer than in real time -- how much 'lead' you can get.  One figure of merit, for instance, is to get a 24 hour model forecast or 'run' in only 1 hour.  This gives you 23 hours to make use of the model before the weather hits.  Obviously the more powerful the computer, the more computing you can do in 1 hour.  But this runs in to some other issues.

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Why is the ocean cold?

Folks reading headlines about record warm oceans might be surprised by this question. But it's a real question, if perhaps from a different viewpoint than you might think.

If we look at the surface of the ocean, we see that most of the ocean is warm. The presentation at the link over-emphasizes the polar regions -- they're actually much less of the earth's area. Even so, over half the ocean -- surface -- is warmer than 20 C.

So you might figure that the volume of the ocean would also be some moderately warm figure, maybe a bit colder since cold water sinks, but still fairly warm. Surely over 10? In fact, the volume of the ocean -- average up every blob of water there is -- averages 3.5 C. Go back to the surface map and take a look at how much of the ocean is that cold. Answer: Not much. Even less when you allow for the fact that the map is exaggerating how big the polar regions are (I get about 14% of the ocean surface was at least that cold on February 26th). The importance of those small areas of cold water is that there is no refrigerator in the ocean. Once water leaves the surface of the ocean (except for one even smaller exception I'll get to), there's no way to make the water any colder. So if you see water that's -1.0 C in the ocean, you know it came from somewhere that had water at least as cold as -1.0 C. It could have been even colder -- the original cold blob might have mixed with a warmer blob of water.

Some of you might have objected up there when I mentioned that the average ocean temperature is 3.5. There's a fairly popular error that says the deep ocean has to be 4 C. It runs this way: Water is densest at 4 C, so as you cool a body of water, once it reaches 4 C all this cold water sinks to the deeps. As you cool the surface further, the water is less dense, so it quits sinking. That leaves you with 4 C water in the deep.

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Oceanography as a job

While it's true that I sometimes whine about parts of my job (mostly, not being able to go do it because I have to do something else instead ... still ...), there's no way I agree with what Popular Science apparently said:
http://rabett.blogspot.com/2009/01/how-did-we-miss-this-from-popular.html
making oceanography one of the worst jobs in science. I did respond over there, and this isn't entirely different from my comments there. But, it's perhaps more germane than a number of things I've commented on lately. So, onward.

I think science is one of the best fields of all to enter for a career. It happens that my main science is oceanography, particularly physical oceanography. But if someone told me that I had to be an astrophysicist instead, I'd be quite happy still. (Ditto quite a number of other fields.) Getting a job can be quite difficult. But if you do get one ... well, here's what I look at in going to work each day:

I get to work with a bunch of very bright people (easy to talk with, whether about the oncoming weather (which isn't as casual for my crowd as for most), or about the Cubs (ok, not so many here are Cubs fans)).

I get paid a comfortable salary. I'm no threat to a pro sports player, particularly not a star. But I can afford to live ok (by my standards) in the Washington DC area.

I don't have to do any heavy lifting or work with obnoxious chemicals. Some scientists do, and those aren't my fields. (But, for those who like it, hey, there's a field of sixteen where it'll be needed.)

I get to find out about what happening in the world before almost anybody. At least for the sorts of the things that I work with. And that means almost anybody. For the sorts of things I work on, we're down to an easily counted number of places. Probably won't need to take off your shoes to do the counting.

When I'm doing science at my work (which isn't always, but does happen) it means that I help make a contribution to what it is that anybody in the world knows about the universe. How cool is that?! Nobody understood or thought that idea before me.

When I'm doing engineering at my job (which is more common), it means that I've succeeded in taking some of our understanding of the universe (anybody, anywhere, any time) and managed, for the first time, to make it possible for someone else to get a practical benefit from it. In my area, 'practical benefit' has included "They Don't Die."

I'll probably add to this list, and invite other scientists to do so. The main thing is, science is a wonderful area to work in. At base, and not already listed: You get paid to do something that you like to be doing.

Introduction to the Oceans

Just a quick look at who they are and what they're made of. The fact that I do polar work leads to me taking a somewhat different accounting of the 'who' side than low and mid-latitude oceanographers tend to. So, for me, the oceans are: Pacific, Atlantic, Indian, Southern, Arctic. The Southern and Arctic oceans are not infrequently neglected. The Arctic can reasonably be called a sea rather than an ocean; that is, it is a body of water that has limited inflow and outflow (the Bering Strait on the Pacific side and Fram Strait on the Atlantic side).

The Southern ocean truly is oceanic rather than sea-like. We polar types consider it separate from the other oceans because of the Antarctic Circumpolar Current. South of this, the Southern Ocean waters are mixed pretty well with each other and are not much like the waters to the north. North of there, the other oceans have greatly limited transport with the Southern Ocean. Currents tend to flow from one of the other three to another of the others, rather than in to the Southern Ocean. Since the Antarctic Circumpolar Current, like all currents, is a dynamic feature, it moves. This means that the boundary location and size of the Southern Ocean (and, conversely, the Pacific, Atlantic, and Indian) fluctuates somewhat in time.

The elements in the ocean, as for most geophysical systems, are mostly a fairly select subset of the periodic table. Although there are over 110 elements known now, only 8 account for most of the ocean. If we take a kilogram of sea water (1000 grams, remember), then there are about:
858 grams Oxygen (O)
107 grams Hydrogen (H)
10.3 g Sodium (Na)
19.5 g Chlorine (Cl)
1.3 g Magnesium (Mg)
0.9 g Sulphur (S)
0.4 g Potassium (K)
0.4 g Calcium (Ca)

Aside: Sodium and Potassium's chemical symbol comes from their Latin names 'Natrium', and 'Kalium', respectively. Their symbols do make sense, at least if you know the right second language.

So, 8 elements, 8 symbols to remember out of the 110+, and you've got well over 99% of the ocean's content. Even better is that the composition of the ocean varies by very little throughout, at least for the major elements. Very scarce elements, like Iron (Fe -- Ferrum) do vary substantially, but they're so rare this doesn't affect the ocean's dynamics.

If we think instead of molecules, the main components are water (H2O), table salt (NaCl), additional salts (KCl, CaCl), and Magnesium Sulphate (MgSO4, epsom salts). Of these, water is the overwhelming majority. Table salt is most of the rest. Viewed in terms of its bulk composition, the ocean is fairly simple. But if we think about living things in the sea, it gets complicated very quickly. Living things depend on elements and chemicals which are very scarce.

The oceans, all together (and however we name them), occupy about 70% of the surface of the earth. This is one reason oceanographers take an interest -- it is most of the surface of our planet. (Calling it 'Earth' is poor naming, we feel. It should be 'Water', or 'Oceania' or something like that.) The average depth of the ocean is about 3730 meters (about 12,200 feet), farther below sea level than almost all land areas are above sea level (land averages about 800 meters, 2600 feet, above sea level; by the time you get to 12,000 feet above sea level, you're on the side of a good mountain).

Later, we'll get more detailed about the ocean. But here's a start on names.