To quantify the impact of SST feedback periodicity on atmospheric intraseasonal variability in the tropical regions

Abstract. This study couples a high-resolution 1-D TKE ocean model (the SIT model) with the Community Atmosphere Model 5.3 (CAM5.3; hereafter CAM5–SIT) configuration, to highlight significant experiments that investigate the influence of different periods of sea surface temperature (SST) feedback, such as 30 minutes, 1, 3, 6, 12, 18, and 30 days, on the Madden-Julian Oscillation (MJO). It substantially breaks through the limitations of flux coupler through air–sea coupling. The aim is to assess the scientific reproducibility and consistency of the findings across different SST feedback cycles in the field of modeling science. Comparing the results to the fifth generation ECMWF reanalysis (ERA5), the high-frequency experiments (C– CTL, C–1day, and C–3days) and low-frequency experiments (C–6days, C–12days, and C–18days) exhibit higher fidelity in capturing various aspects of MJO, except for the C–30days experiment. These aspects in characterizing the basic features of the MJO such as encompass intraseasonal periodicity, eastward propagation, coherence in the MJO band, tilting vertical structure, the lead–lag relationship between MJO- related atmosphere and SST variation, phase 2 column-integrated moisture static energy (MSE) tendency, and the projection of all MSE terms onto the MSE tendency of ERA5 across the Maritime Continent (MC). The MJO simulation performance of this study can be assessed in two ways. Firstly, the high-frequency experiments generally capture MJO characteristics, albeit with slightly lower results compared to ERA5 and NOAA data. Secondly, the low-frequency experiments show robust MJO simulations, which can be attributed to the accumulation of energy (temperature) in the upper ocean. This leads to the accumulation of shortwave and longwave radiations, as well as surface heat fluxes from the atmosphere.