This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Every few years, an unusual warming of surface waters across the central and eastern tropical Pacific—known as El Niño—reorganizes atmospheric circulation worldwide, bringing severe droughts to some continents and torrential rainfall to others. For decades, oceanographers and meteorologists have mapped the intricate internal machinery behind the El Niño–Southern Oscillation (ENSO), from shifting trade winds to subsurface ocean waves.
Yet one fundamental question has always intrigued me: Why does ENSO recur on the specific timescales that it does? In my recent study, published in Frontiers in Earth Science, I explored whether subtle astronomical rhythms in Earth's orbit provide an underlying background tempo for this climate cycle. I approached this question through the lens of astroclimatology, an interdisciplinary bridge connecting celestial mechanics, statistical signal processing and climate dynamics.
When most people hear about astronomy influencing Earth's climate, they think of Milankovitch cycles—vast orbital variations unfolding over tens of thousands of years that pace ice ages. However, Earth's path around the sun also undergoes far subtler, continuous geometric shifts from year to year. As I examined these shorter astronomical variations, I focused on the evolving asymmetry between the March and September equinoxes, combining solar declination and Earth–sun distance.
From this geometry, I isolated two physical descriptors: a geometric measure of Earth's lateral projection asymmetry (ΔLP) and a gravitational descriptor derived from Newton's inverse-square law (1/d², Fi). To test whether these orbital descriptors share any temporal organization with climate variability, I analyzed 78 years of historical ENSO records from 1948 to 2025. Rather than relying on a single statistical tool, I applied three independent mathematical methods: information theory, singular spectrum analysis (SSA) and wavelet coherence.
Across all three approaches, the same recurring timescales emerged: a quasi-biennial rhythm around 2.5–3 years, an interannual band near four years and a broader decadal structure spanning 11–13 years. Seeing three distinct analytical frameworks converge on the exact same temporal bands points to a clear conclusion: the recurrence of El Niño is not simply random noise. At the same time, scientific rigor requires being transparent about what these patterns mean—and what they do not.
My findings do not claim that orbital geometry acts as a simple, direct switch triggering individual El Niño events. Instead, I propose a conceptual working framework centered on energetic preconditioning. Consider how ocean tides operate: relatively small astronomical gradients do not act in isolation, but interact with basin geometry, resonance and fluid dynamics to organize massive movements of water.
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