Global maps of the influence of the SST diurnal cycle on intraseasonal SST variability

Abstract

Abstract The diurnal cycle of SST (DSST) has a significant influence on the intraseasonal SST variability (SST–ISV), as do the associated air–sea fluxes and atmospheric variability. However, current climate models often fail to accurately represent the DSST and its role in the ocean–atmosphere system. Here, we present the first global assessment of the DSST influence on the SST–ISV and its seasonality. Our analysis reveals that the DSST predominantly amplifies the SST–ISV across most regions, with peak contributions exceeding 25% in the equatorial eastern Indian Ocean. Conversely, in areas dominated by strong ocean mesoscale and frontal-scale processes, the DSST exerts a dampening effect on the SST–ISV. The global distribution and seasonality of the DSST contribution are determined mainly by the intraseasonal air–sea interaction processes. These findings highlight the importance of DSST in the ocean–atmosphere system and indicate that incorporating realistic DSST parameterization can enhance the accuracy of climate simulations and predictions.

Keywords

• The diurnal cycle of SST
• Intraseasonal SST variability
• Intraseasonal air–sea interaction