2026/06/19 by Jinning Tong, Xiangzhou Song
Earth and Planetary Sciences · Environmental Science · #Oceanographic and Atmospheric Processes #Climate variability and models #Meteorological Phenomena and Simulations
paper · doi:10.1175/jpo-d-26-0050.1
Abstract The response of air–sea turbulent heat flux (THF) anomalies to sea surface temperature (SST) anomalies is represented by the SST–heat flux feedback parameter. The magnitude of parameter alpha is typically estimated as 30 W m −2 K −1 at midlatitudes. However, the robust quantification of alpha is restricted by substantial uncertainties in THF products, which impedes an accurate understanding of air–sea interactions. Here, we estimate the uncertainty in alpha by combining theoretical sensitivity experiments, Monte Carlo experiments, and constraints from multiproduct and in situ buoy observations. The results of the theoretical experiments indicate that prescribed THF perturbations of 20–30 W m −2 can cause systematic biases of ∼7–15 W m −2 K −1 in magnitude. Analysis based on Monte Carlo experiments reveals that the air–sea specific humidity difference dominates the variance in alpha, with the upper bound of the ensemble standard deviation under identical perturbations reaching ∼12 W m −2 K −1 , whereas the contributions from the wind speed and air–sea temperature difference are relatively small. These results are confirmed by the multiproduct and in situ buoy observations. Moreover, differences among bulk flux algorithms can result in additional algorithm-induced uncertainties ranging from ∼6 to 9 W m −2 K −1 in alpha estimates. Our findings demonstrate that uncertainties in the THF can substantially propagate into SST–heat flux feedback estimates, thus highlighting the need to better constrain near-surface humidity and THF parameterizations to improve representations of air–sea coupling and climate variability. Significance Statement Air–sea turbulent heat flux (THF) feedback reflects the sensitivity of ocean–atmosphere heat exchange to sea surface temperature (SST) changes, but its commonly cited strength at midlatitudes remains difficult to constrain because of high uncertainties in THF estimates. This study investigated how uncertainty in the THF affects our ability to estimate this feedback. The results indicate that 20–30 W m −2 THF uncertainties can induce ∼7–15 W m −2 K −1 feedback biases, with the air–sea specific humidity difference serving as the dominant source. Moreover, differences among bulk flux algorithms introduce additional uncertainties of ∼6–9 W m −2 K −1 . Our results emphasize the importance of improving observations and models of near-surface humidity for understanding and predicting climate variability.