Spin‐up of South Pacific subtropical gyre freshens and cools the upper layer of the eastern South Pacific Ocean

Abstract

Temperature and salinity from the upper 200 m of the water column in the South Pacific Ocean were compared basin‐wide along 32°30′S between 1992 and 2003, based on two vertically and horizontally high‐resolution hydrographic repeat‐sections involving 227 station pairs. Additionally, the seasonal cycles of the upper water column temperature and salinity between 90–140°W and 30.5–34.5°S were established utilizing 1540 ARGO profiles from 2003 to 2007; these were related to the hydrographic sections. Furthermore, South Pacific sea surface temperature trends from 1992 to 2003 were addressed. The surface waters (0–200 m) of the eastern South Pacific Ocean, on average and seasonally adjusted, were clearly fresher by 0.1 in 2003. The seasonally adjusted, depth‐integrated temperature was 0.25°C colder in the same region. We relate the observed temperature and salinity changes to a spin‐up of the subtropical gyre circulation caused by intensified wind stress.