Correction for Olson, Gravitational dynamos and the low-frequency geomagnetic secular variation

INAUGURAL ARTICLE, GEOPHYSICS. For the article “Gravitational dynamos and the low-frequency geomagnetic secular variation,” by P. Olson, which appeared in issue 51, December 18, 2007, of Proc Natl Acad Sci USA (104:20159–20166; first published November 29, 2007; 10.1073/pnas.0709081104), the author notes that on page 20160, left column, last paragraph, line 9, “then ε = −1 in Eq. 3” should instead read: “use in Eq. 3.” This error does not affect the conclusions of the article.