Formation and variability of the South Pacific Sea Surface Salinity maximum in recent decades. Issue 10 (8th October 2013)

• Record Type: Journal Article
• Authors: Hasson, Audrey; Delcroix, Thierry; Boutin, Jacqueline
• Is Part Of: Journal of geophysical research. Volume 118:Issue 10(2013:Oct.)
• Page Start: 5109
• Page End: 5116
• Publication Date: 2013-10-08
• Subjects: maximum sea surface salinity -- SPCZ -- mixed layer salinity budget -- ENSO -- tropical South Pacific Ocean; Oceanography -- Periodicals; 551.4605
• DOI: 10.1002/jgrc.20367
• Languages: English
• ISSNs: 2169-9275

Abstract

Abstract : [1] This study investigates causes for the formation and variability of the Sea Surface Salinity maximum (SSS > 36) centered near 18°S–124°W in the South Pacific Ocean over the 1990–2011 period at the seasonal time scale and above. We use two monthly gridded products of SSS based on in situ measurements, high‐resolution along‐track Voluntary Observing Ships thermo‐salinograph data, new SMOS satellite data, and a validated ocean general circulation model with no direct SSS relaxation. All products reveal a seasonal cycle of the location of the 36‐isohaline barycenter of about ±400 km in longitude in response to changes in the South Pacific Convergence Zone location and Easterly winds intensity. They also show a low frequency westward shift of the barycenter of 1400 km from the mid 1990s to the early 2010s that could not be linked to the El Nino Southern Oscillation phenomena. In the model, the processes maintaining the 22 year equilibrium of the high salinity in the mixed layer are the surface forcing (∼+0.73 pss/yr), the horizontal salinity advection (∼−0.37 pss/yr), and processes occurring at the mixed layer base (∼−0.35 pss/yr). Key Points: Study of high SSS core useful to understand climatic and hydrological changes Seasonal variability of the max SSS position linked to the SPCZ and Easterlies. We discuss the 2-decade 1400 km westward shift of the core barycentre