Warming and circulation change in the eastern South Pacific Ocean

Deep-ocean temperature, salinity and dissolved oxygen observations in the e astern South Pacific Ocean collected during the late austral fall in 1995 a re compared with observations made there 28 years earlier during the same s eason and similar El Nino-Southern Oscillation phase. Warming observed abov e 800 m at 43 degrees S reflects the production of warmer Subantarctic Mode Water in recent decades. Warming observed above 1600 m at 28 degrees S is due to downward isotherm displacement and southward movement of water masse s by 100-200 km, as revealed by joint analysis of temperature and oxygen da ta. Such changes would be expected for a weaker subtropical gyre in the Sou th Pacific. An observed oxygen decrease between about 1800 m and 2900 m at 28 degrees S may indicate enhanced southward, boundary current flow at mid- depths off Chile.