Sea Surface Salinity and Temperature Seasonal Changes in the Western Solomon and Bismarck Seas
[26-Feb-2014] Delcroix, T., Radenac, M.H., Cravatte, S., Gourdeau, L., and Alory, G.
Presented at the 2014 Ocean Sciences Meeting
Small SST and SSS (an indicator of iron-rich PNG river outflows) changes in the Solomon and Bismarck Seas may be transported to the equatorial Pacific and have strong climatic and biological impacts. We analyze mean and seasonal changes in SSS and SST, using 1977-2012 in situ data collected from Voluntary Observing Ships. Co-variability of these two variables with surface wind, altimeter-derived coastal current anomalies, precipitation, and Sepik river discharge is examined. SSS and SST show large annual oscillations in the Solomon Sea, with the saltiest and coldest waters occurring in austral winter due to horizontal advection. In contrast, they show large semi-annual oscillations in the Bismarck Sea. Here, SSS is minimum in April/May following the maximum Sepik river discharge, and in November/December. SST is minimum in January/February, when the northwest monsoon winds drive coastal upwelling, and in July/August, when cold waters from the Solomon Sea are imported through Vitiaz Strait by the New Guinea Coastal Current. A high resolution model partly corroborates the conclusions we derive from observations. The impacts of ENSO on SSS and SST are also discussed.