In a groundbreaking study published in Nature Geoscience, researchers reveal a subtle yet critical dynamic in the processes governing tropical cyclones (TCs) amid the contexts of rapidly warming seas. Their findings challenge prevailing assumptions about the self-regulating cooling effect induced by tropical cyclones as they traverse the ocean surface, unveiling a weaker-than-anticipated SST (sea surface temperature) cooling mechanism even in the face of accelerating ocean warming. This nuanced interplay between tropical cyclone intensity and the warming ocean surface introduces profound implications for future weather forecasting and climate modeling.
Tropical cyclones are among the most devastating natural phenomena, primarily exerting their destructive force through intense winds and associated storm surges. Central to the dynamics of TCs is the interaction with ocean surface temperatures, which not only supply energy but also modulate the cyclone’s potential intensity through feedback mechanisms. The study utilizes global TC best-track data spanning three decades (1992 to 2021), meticulously extracted from the International Best Track Archive for Climate Stewardship (IBTrACS), and enriched by the Advanced Dvorak Technique Hurricane Satellite (ADT-HURSAT) dataset. These datasets collectively provide comprehensive, robust information on cyclone location, intensity, and progression.
To focus on the TCs contributing the most to global damage and mortality, the research narrows its scope to storms that achieve Category 1 or higher on the Saffir–Simpson Hurricane Scale. Moreover, to ensure consistency and minimize confounding effects from coastal and polar ocean dynamics, data points poleward of 40° latitude and within shallow coastal ocean areas (depth less than 1,000 meters) are excluded. This rigorous data curation yields 1,324 TC cases, encompassing over 17,000 track points, establishing a substantial foundation for robust analyses.
A pivotal innovation in this study is the deployment of drifter-observed SST data, which measure sea temperatures approximately 10–20 centimeters below the surface, providing a ‘foundation’ SST devoid of diurnal warming artifacts. The influence of tropical cyclones on upper ocean temperatures is characterized using paired observational strategies comparing storm-time SST with pre-storm baseline SST, carefully controlled for spatial and temporal proximity to isolate cyclone-induced cooling. Over 32,000 storm-local SST observations meeting strict criteria of temporal and spatial pairing ensure a high fidelity examination of the thermodynamic impact induced by TCs.
Additionally, the team explores the temporal evolution of TC-induced SST cooling by analyzing data averaging within 100 km of cyclone centers over periods spanning five days before and after cyclone passage. Their analyses incorporate sensitivity assessments using varying spatial buffers and include Lagrangian tracking approaches to account for mesoscale oceanic variability, such as eddies and current velocity anomalies. These rigorous controls and cross-validations conclude that mesoscale ocean features exert minimal bias on the observed average cooling signals, strengthening confidence in their findings.
Impressively, the analyses demonstrate an estimated daily average SST cooling of approximately −0.67°C attributed to tropical cyclones, consistent across 6-hourly and daily averaging schemes. Notably, this uniformity suggests that temporal misalignments between satellite and in situ observations are negligible when aggregated over extensive datasets. A comprehensive comparison between drifter data and satellite microwave SST measurements validates the reliability of satellite estimates, offsetting prior concerns about measurement depth discrepancies affecting TC cooling analysis.
Further, the study investigates the sea surface temperature trends in tropical cyclone-active regions, defined as climatological SST zones above 27°C during peak TC seasons. By excluding regions with minimal TC activity and employing a suite of SST reanalysis and reconstruction datasets—such as ORAS5, ERA5, ERSST, and HadISST—the researchers rigorously establish warming trends unconfounded by regional variability. The observed rapid warming in these active regions portends important implications for the strength and distribution of future cyclone activity.
Central to the study’s theoretical framework is the concept of potential intensity (PI), a parameter embodying the maximal achievable intensity of a tropical cyclone given prevailing atmospheric and oceanic conditions. Elaborated through Emanuel’s PI formulation, this study integrates observed storm-local SST and detailed atmospheric sounding data to compute spatially and temporally resolved PI fields. Critical coefficients such as the enthalpy transfer ratio and the drag coefficient are carefully calibrated to capture the complexity of heat and moisture exchanges between ocean surface and atmosphere in the TC context.
Leveraging an autoregressive statistical model, the team simulates synthetic TC intensity time series grounded in observed PI trends. This analytical framework posits that TC intensity varies stochastically between established intensity thresholds, aligning with empirical data of cyclone behavior. Through this, they forecast the trajectory of mean cyclone intensity improvements linked to SST warming, evidencing a complex interplay moderated by this weakened self-induced cooling mechanism.
One of the study’s most striking outcomes lies in the model-based evaluation of TC-induced SST cooling within high-resolution climate simulations. An ensemble of five state-of-the-art outputs from the HighResMIP initiative—covering multifarious atmospheric and oceanic coupled climate projections—unanimously demonstrate a recurrent overestimation of inner-core SST cooling, compared to observational benchmarks. This overcooling effect persists despite underestimations of the actual TC intensity in these models, indicating a systemic bias that could skew future climate projections for tropical cyclone behavior and impacts.
To further isolate the mechanisms underpinning SST cooling and its representation in numerical models, the authors employ the coupled COAWST modeling system, integrating atmospheric (WRF) and oceanic (ROMS) components. With high spatial resolution (down to 9 km grids) and sophisticated physical parameterizations, the model simulates 22 TC events in the western North Pacific. Control versus experimental runs with reduced vertical mixing elucidate the critical role of ocean mixing processes in generating SST cooling and, consequently, their influence on TC intensity forecasts.
Enthalpy flux, representing the combined sensible and latent heat fluxes from ocean to atmosphere, is meticulously computed to assess the energy budget dynamics governing tropical cyclones. Using robust bulk aerodynamic formulas, these fluxes depend on measured SST, air temperature, mixing ratios, and wind speeds, integrating crucial thermodynamic drivers of TC intensity and sustainability. Comparisons between fluxes based on satellite versus in situ SST suggest that prior estimations might be biased, influencing cyclogenesis assessments in climate models.
This research significantly advances understanding of the self-regulating mechanisms of tropical cyclones as they interact with a warming ocean surface. The finding that TC-induced SST cooling is weaker than previously hypothesized challenges established feedback concepts, carrying ramifications for the frequency, strength, and lifecycles of tropical cyclones under climate change scenarios. Moreover, identifying systemic biases in state-of-the-art climate model simulations alerts the research community to critical deficiencies in simulating cyclone-ocean feedbacks, emphasizing the need for model improvement to accurately project future cyclone risks.
Given that intense tropical cyclones are disproportionately responsible for human and economic losses, insights into their intensity modulation through ocean-atmosphere interactions hold substantial societal relevance. This study’s comprehensive integration of observational datasets, theoretical modeling, and climate simulation underscores the complex, evolving dynamics shaping tropical cyclone behavior in a warming world, setting a new benchmark for future research directions.
The significance of this study is further underscored by its meticulous approach to data quality and methodological rigor. By excluding confounding geographic zones, twins analyses of in situ and satellite data, and testing sensitivity across multiple spatial and temporal scales, the authors demonstrate an exceptional commitment to ensuring robustness and reliability. This approach not only breaks new ground in tropical meteorology but also serves as a methodological exemplar for multidisciplinary climate science.
Future research, as catalyzed by these findings, will likely pivot towards enhancing realism in coupled ocean-atmosphere models, especially focusing on resolving ocean vertical mixing processes and their feedback on sea surface temperatures. Such improvements are crucial to realistically simulating the evolving intensity and frequency distributions of tropical cyclones amid accelerating climate warming—an urgent endeavor given the existential threats posed by these storms globally.
In conclusion, this seminal work elucidates an unexpected facet of tropical cyclone thermodynamics: their capacity to induce sea surface cooling is less robust in an era of rapid ocean warming than previously assumed. This weak self-induced cooling effect not only affects the intensity and evolution of TCs but also challenges current paradigms in climate projection models. As rising sea surface temperatures are a key driver of cyclone strength, this nuanced feedback mechanism warrants deep consideration in future climate resilience planning and atmospheric science research.
Subject of Research: Tropical cyclones, sea surface temperature cooling, climate change impacts, potential intensity, observational data, climate model evaluation.
Article Title: Weak self-induced cooling of tropical cyclones amid fast sea surface warming.
Article References:
Guan, S., Huang, M., Cai, W. et al. Weak self-induced cooling of tropical cyclones amid fast sea surface warming. Nat. Geosci. (2026). https://doi.org/10.1038/s41561-025-01879-x
Image Credits: AI Generated
DOI: https://doi.org/10.1038/s41561-025-01879-x
Keywords: tropical cyclones, sea surface temperature, ocean-atmosphere interaction, potential intensity, climate models, high-resolution climate simulations, enthalpy flux, vertical ocean mixing
