Shigeru Aoki

Repeat summer hydrographic observations along 140°E are used to document significant changes in the properties of the Adélie Land Bottom Water (ALBW) between the mid‐1990s and 2002–2003. Water on the 28.35 kg·m −3 neutral density surface cooled by 0.2°C and freshened by 0.03 psu between 1994 and 2002. By re‐occupying the same stations in the same season, the effects of seasonal variability and spatial variability were minimised allowing the signal of water mass changes to be clearly identified.

Interdecadal water mass changes in the Indian ‐ Western Pacific sectors of the Southern Ocean were investigated using the Japanese Antarctic Research Expeditions and historical hydrographic observations from the 1950s to 1990s. Freshening and cooling occurred on the neutral density surfaces of 27.0 kg·m −3 equatorward of Sub‐Antarctic Front. Results for the area south of the Polar Front show warm and saline anomalies and oxygen decreases on the surfaces around 27.9 kg·m −3 , which correspond to

Long‐term variations of subsurface layer temperature were examined for 32 years (1966–1998) of continuous observations in the Indian sector of the Southern Ocean. The data analyzed consist of observations from Japanese Antarctic Research Expeditions and also from other countries. Significant warming trends of about 0.004°C × yr −1 were observed at all depths from 200 to 900 m to the north of the southern Antarctic Circumpolar Current (ACC) front [ Orsi et al. , 1995 ]. The rates of warming incre

Large‐scale sea level variations around Antarctica were studied and their relationship with atmospheric variations was investigated. Tide gauge data at five coastal stations were used. Coherent sea level variations were clearly detected for all stations on intraseasonal time scales. The coherent variations had significant negative correlations with an index of the atmospheric annular mode variation (Antarctic Oscillation). Coherence was significant for periods from 10 to 100 days with negligible

Abstract A large land‐fast sea ice breakup occurred in 2016 in Lützow‐Holm Bay, East Antarctica. The breakup caused calving from the Shirase Glacier Tongue. Although similar breakups and calving have been observed in the past, the timing and magnitudes are not well‐constrained. The ice's breakup latitude during 1997–2016 was analyzed to investigate the variables controlling breakup and examine correlation with local calving for a longer period. The breakup latitude in April had a persistently hi

The Antarctic continental margin supplies the densest bottom water to the global abyss. From the late twentieth century, an acceleration in the long-term freshening of Antarctic Bottom Waters (AABW) has been detected in the Australian-Antarctic Basin. Our latest hydrographic observations reveal that, in the late 2010s, the freshening trend has reversed broadly over the continental slope. Near-bottom salinities in 2018-2019 were higher than during 2011-2015. Along 170° E, the salinity increase be

The Geosat radar altimeter data during the first year of its exact repeat mission are analyzed to investigate the behavior of individual anomalies of sea surface dynamic topography (SSDT) and their statistical properties in the Kuroshio Extension region. The SSDT anomalies are compared with mesoscale anomalies of sea surface temperature (SST) derived from satellite radiometer data. Remarkable baroclinic anomalies are detected in the time series of both SSDT and SST, and their westward propagatio