Abstract
Two prominent interannual atmospheric fluctuations, the El Niño-Southern Oscillation in the troposphere-ocean system and the Quasi-Biennial Oscillation in the equatorial stratosphere, account for most of the observed interannual length-of-day (LOD) variation from 1964 through 1987, with a relative contribution of about 2 to 1. Thus the atmosphere-LOD connection extends from seasonal and shorter periods to interannual periods up to about 10 years.