The Chandler Wobble

I just heard a story on NPR this morning on the Chandler wobble, a phenomenon that causes the Earth to wobble slightly as it spins. A while back, Cecil had a column on the very same wobble, in which he says,

Well, looks like someone’s ready to collect. In a nutshell, the theory is that wind-driven water is redistributed around the globe, loading the crust in different places and “ringing the Earth like a bell.”

The research is to be published in an upcoming journal article (Geophysical Reviews? I can’t remember; sorry.)

(I think a synopsis of the story will be posted on NPR’s website at this address, but as of this writing, nothing’s there.)

A few more details are available at

Thanks, Balance. Just to clarify, the article in question will be published in the August 1 edition of Geophysical Research Letters, published by the American Geophysical Union. Their explanation of the Chandler wobble, copied from the press release quoted in part at the site Balance mentions, is,

Which sounds more scientific than my paraphrase.

As an added bonus, the link I gave to NPR is now up; I believe they will subsequently link in a Real Audio file of the radio story. If you download it, be sure to listen for the part where the reporter says something like, “Gross used computer simulations, called models, to [blah blah].” I just thought the gratuitous synonym was funny.

I haven’t seen Dr. Gross’s article yet. GRL is a letters journal, which publishes short descriptions of recent advances.

Previously, the difficulty of finding the Chandler wobble in meteorological data was that the Chandler wobble has a period of 14 months and the meteorological data has a strong (!) 12 month component. Over the course of seven years, the 12 month signal goes from in phase to out of phase and back, and the net result is no overall excitation of the wobble. On the other hand, a noisy signal, or Gaussian noise, has power at all frequencies and so could pump up the wobble–but it could just as easily damp it out. There, I didn’t use “dampen.”

Just wanted to mention that a recent CNN article on this subject, “Scientists no longer waver on Earth’s wobble”, mentions the Straight Dope!

I don’t know how long CNN links remain valid, so I disclaim any responsibility when the link goes dead.

Notice that they use my word “dampen” instead of “damp.”

If Cecil would answer afca’s question about cabbits, the Straight Dope could become the online equivalent of CNN. For everybody, I mean.

I’m just crushed, RM. I thought you were gonna be the one to solve that wobble thing.

The race is not always to the swiftest, my dear.