Rectification of the Intraseasonal SST Variability by the Diurnal Cycle of SST Revealed by the Global Tropical Moored Buoy Array. Issue 1 (11th January 2021)

• Record Type: Journal Article
• Authors: Yan, Yunwei; Zhang, Lei; Yu, Yi; Chen, Changlin; Xi, Jingyuan; Chai, Fei
• Is Part Of: Geophysical research letters. Volume 48:Issue 1(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-01-11
• Subjects: diurnal cycle of SST -- intraseasonal SST variability -- tropical oceans; Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1029/2020GL090913
• Languages: English
• ISSNs: 0094-8276

Abstract

Abstract: It has been suggested that the intraseasonal sea surface temperature (SST) variability in the tropical oceans can be amplified by the diurnal cycle of SST (dSST). Here, by analyzing the global tropical moored buoy array for the first time, we find that the intraseasonal SST variability is indeed amplified by the dSST in most of the tropical oceans, especially in the Indo‐Pacific warm pool, but weakened in the equatorial cold tongues of the Pacific and Atlantic Oceans. Such a divergent response is associated with the difference in atmosphere‐ocean interaction processes over these two regions. In the warm pool region, SST responds to the intraseasonal atmospheric variability, resulting in in‐phase intraseasonal fluctuations between SST and dSST that amplify the intraseasonal SST variability. However, in the cold tongue region, SST drives the atmospheric changes, which leads to out‐of‐phase intraseasonal fluctuations between SST and dSST and thus the inhibition of the intraseasonal SST variability. Plain Language Summary: The diurnal cycle is a fundamental timescale in the climate system, which has important nonlinear impacts on the variability on longer timescales. Previous studies have suggested that the diurnal cycle of sea surface temperature (SST) amplifies the SST variability on intraseasonal timescales of 20–90 days in the tropical region. By analyzing ocean temperature measurements from moored buoys located in the global tropical oceans, we find that the aforementioned amplification effect does exist in most of the tropical oceans, however, the diurnal cycle of SST weakens the intraseasonal SST variability in the equatorial eastern Pacific and Atlantic Oceans. Such contrasting results are associated with the different interaction processes between the atmosphere and the ocean over these regions. This is the first report of the inhibition effect, adding a new insight into the impact of the diurnal cycle of SST on intraseasonal SST variability. Key Points: The rectification of the intraseasonal sea surface temperature (SST) variability by the SST diurnal cycle is revealed by the global tropical moored buoy array The intraseasonal SST variability is enhanced by the diurnal cycle in the Indo‐Pacific warm pool but weakened in the equatorial cold tongues These divergent responses are associated with the difference in atmosphere‐ocean interaction processes over these two regions