Variability of Salinity and Temperature Anomalies in South Pacific Tropical Water

Developing a new understanding of the variability of temperature and salinity anomalies in South Pacific Tropical Water (SPTW) and their downstream impacts may possibly provide a mechanism for ENSO modulations. The anomalies of SPTW are examined using Argo data. We use quality controlled gridded monthly data for the period 2005 to 2014 from Asian-Pacific Data Research Center of the IPRC, trying to investigate density-compensated spiciness anomalies. Annual mean salinity anomalies, temperature anomalies and potential density anomalies averaged over 24 < σ_θ< 25 kg m^-3 isopycnals are plotted, where the anomalies are deviations from the mean field of 2005 to 2014 monthly climatology and each depth at each gridded point has its own mean. Two salinity/temperature anomalies are found during the studied period. A warm/salty anomaly appears in the region of 130°W-110°W at about 15°S in 2005, propagates to the west and ends in 2009. In 2011 a cool/fresh anomaly is found at the subduction region of SPTW at about 18°S and 120°W, which migrates northwestward to 170°W-150°W and 10°S in 2014. Downstream, the potential density anomaly appears to be slightly negative for the warm/salty anomaly and slightly positive for the cold/fresh anomaly, showing temperature anomalies are having a stronger influence on density than the salinity anomalies for SPTW. We are investigating the possible connections that these salinity/temperature anomalies could have to Rossby waves and atmospheric forcing.