The relationship between the interannual variation of earth's rotation and El Nino events

We analyzed the relationship between the earth's rotational variation and sea-surface temperature anomaly. By means of using Fast Fourier Transform (FFT) bandpass filter on the change of length-of-day (Delta LOD) data, the interannual variation series having time periods greater than 1.5-year and less than 8-year was obtained. Time series analyses of the interannual variation, which corresponds to the El Nino period, reveal a close linkage between the earth's rotation and El Nino. A detailed comparison suggests, that six of seven El Nino events are nearly synchronous with the interannual variation of the earth's rotation, and all Delta LOD peak are in El Nino years except 1991-92, which means the interannual variation of the earth's rotation in these years is relatively slow. The correlation between Delta LOD and sea-surface temperature is about 0.517 (1 month-lag), which far exceeds the 99% significance level.