Magnitude and Phase of Diurnal SST Variations in the ACCESS‐S1 Model During the Suppressed Phase of the MJOs. Issue 12 (26th December 2019)

• Record Type: Journal Article
• Authors: Hsu, Je‐Yuan; Hendon, Harry; Feng, Ming; Zhou, Xiaobing
• Is Part Of: Journal of geophysical research. Volume 124:Issue 12(2019)
• Page Start: 9553
• Page End: 9571
• Publication Date: 2019-12-26
• Subjects: Oceanography -- Periodicals; 551.4605
• DOI: 10.1029/2019JC015458
• Languages: English
• ISSNs: 2169-9275

Abstract

Abstract: Diurnal variations of sea surface temperature (DV SST) can affect the heat and moisture fluxes at the air‐sea interface during the suppressed phase of the MJO, thereby conditioning a favorable atmosphere environment for the subsequent MJO active phase. In order to better understand the causes and impacts of DV SST, and the modeling requirements for faithfully simulating these processes, we explore the DV SST and their influences on the air‐sea fluxes during the suppressed phases of three MJO events using a global coupled model, ACCESS‐S1, which has a 1‐m vertical resolution near the ocean surface and coupling frequency of 1 hr. Compared with the MTSAT‐1R satellite SST measurements, ACCESS‐S1 is able to simulate the magnitude of the DV SST reliably but has a phase delay in simulated peak SST of ~3 hr. Imposing an instant vertical mixing in the upper 10 m in ACCESS‐S1 would suppress the DV SST by >1°K and decrease the peak (>30 W m −2 ) and daily averaged latent heat flux. On the other hand, changing the atmosphere‐ocean coupling frequency within several hours mostly affects the DV SST phase instead of magnitude. Extreme DV SST (>1°K) occurs only when ocean mixing layer depth = 1 m. It implies that vertical resolution of ≤1 m near the sea surface is important for the coupled models to simulate both the magnitude and phase of DV SST accurately and thereby the air‐sea heat fluxes in future model forecast of the MJO. Key Points: Using the vertical resolution of 1 m near the ocean surface affects DV SST more than using high coupling frequency, e.g., 1 hr Global coupled model ACCESS‐S1 can predict the DV SST magnitude reliably but with the phase shift of 3 hr Effects of DV SST magnitude on the air‐sea heat fluxes are more significant than the DV SST phase