Yunwei Yan, Lei Zhang, Yi Yu, Changlin Chen, Jingyuan Xi, Fei Chai

Published in Geophysical Research Letters, DEC 2020

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.

Fig. (a) Intraseasonal (20–90 days bandpass filtered) STD of SST (°C), (b) difference of the intraseasonal STD between SST (with the diurnal cycle) and the foundation SST (without the diurnal cycle) (°C), and (c) ratio of the intraseasonal STD difference to the intraseasonal STD of SST (%) in the tropics. Filled circles (triangles) denote positive (negative) values. Gray contours denote annual mean SST. STD, standard derivation; SST, sea surface temperature.

Yan, Y., Zhang, L., Yu, Y., Chen, C., Xi, J., & Chai, F. (2021). Rectification of the intraseasonal SST variability by the diurnal cycle of SST revealed by the global tropical moored buoy array. Geophysical Research Letters, 48, e2020GL090913. https://doi.org/10.1029/2020GL090913.