THE EFFECT OF THE EL-NINO SOUTHERN OSCILLATION ON THE EXCITATION OF THE CHANDLER MOTION OF THE EARTHS POLE

The redistribution of air and water masses between the Pacific and Ind ian oceans during the El Nine Southern oscillation (ENSO) changes the components of the Earth's inertia tensor and shifts the position of th e pole of the Earth's rotation. The spectrum of the ENSO has component s with periods of about 6, 3.6, 2.8, and 2.4 years. Except for 2.8 yr, these periods are all multiples of the Chandler period T = 1.2 yr. A nonlinear model for the Chandler polar motion (CPM) has been construct ed based on this empirical fact. In this model, the ENSO excites the C PM by acting on the Earth at the frequencies of combination resonances . At the same time, the CPM induces a polar tide in the atmosphere and the World ocean, which orders the ENSO. As a result, the dominant com ponents in the noise spectrum of the ENSO are those with the periods i ndicated above.