Remote Influences of Land Surface Temperature and their Implications for Sea Surface Temperature Patterns

TL;DR

This study investigates how regional land surface temperature changes influence sea surface temperature patterns, revealing land warming's role in modulating Pacific climate variability through dynamical atmospheric pathways.

Contribution

It demonstrates the dynamical mechanisms linking regional land warming to SST pattern changes using coupled climate model simulations.

Findings

LST warming over South America enhances La Niña-like SST patterns.

Land warming over North America and Africa affects Pacific and Atlantic SSTs.

Warming over the Maritime Continent or Tibetan Plateau has minimal SST impact.

Abstract

The spatial pattern of sea surface temperature (SST) plays a central role in shaping the climate system, yet the influence of land surface temperature (LST) remains poorly understood. Using a state-of-the-art coupled ocean--land--atmosphere model, we examine the model's response to regional LST perturbations imposed through LST nudging and idealized time-dependent ramp warming simulations. We find that LST warming over South America strengthens the tropical Pacific zonal SST gradient, yielding a more La Ni\~na--like mean state. Enhanced LST increases the zonal contrast in diabatic heating and excites stationary Rossby wave responses, which reinforce alongshore winds and coastal upwelling in the eastern Pacific. This provides a dynamical pathway linking regional land warming to changes in the equatorial Pacific mean state. Similar responses are found for warming over North America, accompanied by North Pacific cooling, and for warming over Central Africa, coupled with tropical Atlantic cooling. In contrast, warming over the Maritime Continent or the Tibetan Plateau does not induce significant SST pattern changes. Historical simulations nudged toward observed LST exhibit cooling in the tropical southeast Pacific, with the tentative implication that uncertainty in LST may contribute to model-simulated SST biases during the historical period.