Surface temperature and salinity characteristics of the california current system

Temperature and salinity (TS) conditions are a framework to characterize water masses that allow us to describe and understand dynamic processes like currents and how they change. While commonly used at depth, TS conditions at the ocean's surface and in coastal areas are not normally analyzed because of the concurrence of multiple processes that impact TS values in small scales. However, TS characteristics at the surface can give us information about regional changes in air-sea-land interactions and processes. Multiple platforms monitor salinity at all times, but it is expensive and mostly done at specific locations. The spatial coverage achieved with satellite data is still unsurpassed despite the shallow-depth and coastal limitations. Furthermore, for remote areas, satellite data might be the only available or continuous data. In this study, we investigate the use of remotely sensed sea surface temperature (SST) and sea surface salinity (SSS) data to identify regions with unique water characteristics along the California Current System (CCS), and assess their accuracy in comparison with data from 13 Saildrone cruises. We found that a cluster analysis of in situ data identifies six distinct TS regions, and that co-located and gridded satellite data did well at reproducing those areas at seasonal scales, despite biases. The only area that shows difference is the northern California coastal upwelling region, which can be due to coastal biases and/or the episodic nature of deep-water upwelling in this area during the summer.