The two El-Nino types and the Length-of-day changes

At the interannual to decadal timescale, the changes in the Earth rotation rate are linked with the El-Nino Southern Oscillation phenomena. As climatic studies demonstrate that two types of El Nino events exists; namely, Cold-Tongue and Warm Pool events. We investigate how each of them affects the Earth rotation rate variations; in particular, we show that Cold-tongue events are associated with stronger variation of the Atmospheric Angular Momentum. We explain this difference by noting that a stronger low pressure occurs on the West coast of the North and South America during those events, which generates stronger mountain torques over the Andes and Rocky Mountains.