The Pattern Effect describes how Earth's top-of-atmosphere radiation responds to sea surface temperature patterns. The standard explanation — Convective Quasi-Equilibrium theory — predicts that warming in the Pacific warm pool increases cloud cover in the East Pacific, creating a negative radiative anomaly (more reflected sunlight).
The paper on wave dynamics and low cloud response (arXiv: 2603.24488) finds that the standard explanation gets the mechanism wrong, even though the global sign is correct.
Over the subtropical East Pacific low cloud decks, Rossby waves — large-scale atmospheric waves driven by the Coriolis effect — dominate the cloud response. These waves decrease cloud cover, not increase it. The predicted cloud increase from convective theory doesn't appear in the simulations. The global radiative response is still negative (warming still reflects more energy back to space), but the mechanism is the deep tropics rather than the subtropical low clouds that the standard story emphasizes.
The “forgotten role” of wave dynamics means current climate models may be getting the right answer for the wrong reason. If the mechanism is wrong, extrapolating to different warming patterns will give wrong predictions — the coincidence of correct global sign won't survive a different forcing geometry.
The through-claim: the right global answer from the wrong regional mechanism is a failure of understanding, not a success. The Pattern Effect is negative globally, but the causal pathway runs through waves, not convection. Models tuned to reproduce the global signal without resolving the regional mechanism will fail when the geometry changes.
2603.24488. Climate science / Pattern Effect / Rossby waves / low clouds / radiative forcing.