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Abstract

The excess heat due to the global warming has already penetrated and stored to the mid- and deep ocean, based on a huge amount of recent Argo and other observational data (IPCC, 2021). An upward trend of ocean heat content (OHC) has also been shown from various data sets with error bars. However, the mechanisms of the warming slowdown called the hiatus period have not yet been fully understood, although oceanic influences are presumably considered to be a strong factor, based on studies using climate models and observational data. In order to elucidate the theme, capturing actual state of oceanic variability is crucial. In this study, we utilized Argo temperature data which has been accumulated for more than 20 years to make gridded data and attempted to statistically describe the characteristics of OHC variability during and after the hiatus period. The slowdown and subsequent increase in temperature rise noted in previous studies is also evident in the observed OHC variability, which is particularly similar in the tropics, North Pacific, and North Atlantic regions. In the Southern Hemisphere, on the other hand, the hiatus period seems to stop earlier, and warming begins.A similar trend is hardly seen at depths below 300 m. These characteristics indicate that the events occur mainly above the main thermocline and follows the temperature fluctuations more closely in the Northern Hemisphere. The detailed spatial distribution of OHC variability and seasonal variability will be presented in the session.