Seasonal Variability of Global Intraseasonal SST Perturbations from 1982 to 2021

Abstract The seasonal variability of the intraseasonal SST perturbations is analysed based on the high spatial-temporal resolution and long-time series (1982-2021) OISST data. There are two bands of high intraseasonal variability (ISV, 20-90 days), one band is along the equatorial eastern Indian and western Pacific Oceans, the other is along the axis of the Antarctic Circumpolar Current (ACC). For large-scale perturbations, during boreal winter, the ISV of SST is large south of the equator, especially south of 30°S. During boreal summer, the situation is opposite and the ISV is more concentrated north of 30°N. During boreal spring, the ISV is increasing north of equator. During boreal autumn, the ISV is increasing south of equator while decreasing north of equator. For small-scale perturbations, the ISV of SST is large all the time over the Southern Ocean and western boundary currents. In the tropical ocean, the small-scale ISV in the eastern Pacific Ocean is apparent in summer and autumn. Compared to large-scale ISV, the distribution areas of the small-scale ISV are apparently narrower.