On the Seasonal Cycle of Sea Surface Salinity In the Gulf Stream from Aquarius/SAC-D: A Data Comparison
[12-Nov-2014] Vazquez, J., Tang, W., Hayashi, A., and Tsontos, V.
Presented at the 2014 Aquarius/SAC-D Science Team Meeting
Three different sea surface salinity (SSS) data sets were used for comparing the annual signal of salinity in the Gulf Stream. These were both the Project version 3.0 SST-adjusted and non-adjusted data sets as well as SSS based on the v3.0 Combined Active-Passive (CAP) algorithm. A simple empirical orthogonal function (EOF) analysis was applied to all three data sets to resolve and attribute key components of the observed variability. All three data sets showed that the first mode accounted for more than 90% of the variability and was associated with the Gulf Stream. All three data sets indicated a magnitude for the annual signal of around 0.5 PSU, with a high in the late winter-early spring time frame. The phase of the annual cycle was compared with SST gradients, OSCAR current speeds, and Wind Speed from CAP to determine if the annual cycle was being driven by advection or air-sea coupling. Maxima in wind speed, SST gradients, and SSS all occurred in the winter to spring period. This indicates that variation in SSS within the Gulf Stream is most likely being driven by changes in evaporation and not advection from the South. An EOF analysis of the covariance between the SSS and wind speed yielded correlations of 0.70, indicative of the coupling between wind speed and salinity. Future work will compare directly with evaporation and precipitation data.