This is what happens with the Earth's excess angular velocity (momentum) over time

![aam](http://imageshack.com/a/img673/2352/9VxGW8.gif)

Note the strong hiccup ~1983 where it appeared the earth's rotation slowed down temporarily.

That coincides with the point that the SOI model also loses coherence with the underling data.

This is a prior analysis:
http://www.earth.sinica.edu.tw/~bfchao/publication/eng/1995%20Wavelet%20Analysis%20Provides%20a%20New%20Tool%20for%20Studying%20Earth's%20Rotation.pdf
Chao, Benjamin Fong, and Isao Naito. "Wavelet analysis provides a new tool for studying Earth's rotation." Eos, Transactions American Geophysical Union 76.16 (1995): 161-165.

![chao](http://imageshack.com/a/img537/369/TrpjEu.gif)

Like they say, what is confusing is the QBO has the opposite polarity when comparing the two events.