Weather and climate modelers understand pretty well how seasonal winds and ocean currents affect El Niño patterns in the eastern equatorial Pacific Ocean, impacting weather across the United States and sometimes worldwide.
Weather and climate modelers understand pretty well how seasonal winds and ocean currents affect El Niño patterns in the eastern equatorial Pacific Ocean, impacting weather across the United States and sometimes worldwide.
But new computer simulations show that one driver of annual weather cycles in that region — in particular, a cold tongue of surface waters stretching westward along the equator from the coast of South America — has gone unrecognized: the changing distance between Earth and the sun.
The cold tongue, in turn, influences the El Niño-Southern Oscillation (ENSO), which impacts weather in California, much of North America, and often globally.
The Earth-sun distance slowly varies over the course of the year because Earth’s orbit is slightly elliptical. Currently, at its closest approach — perihelion — Earth is about 3 million miles closer to the sun than at its farthest point, or aphelion. As a result, sunlight is about 7% more intense at perihelion than at aphelion.
Read more at University of California - Berkeley
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