Diurnal Sea Surface Salinity Variation Detection in Aquarius Data
[26-Feb-2014] Fine, E.C., Bryan, F.O., and Large, W.G.
Presented at the 2014 Ocean Sciences Meeting
Small, but measurable, diurnal variations in sea surface salinity (SSS) have been observed at select locations with adequate in situ instrumentation. These variations result primarily from imbalances between surface freshwater fluxes and vertical mixing of deeper water to the surface. The diurnal variations should be reflected as differences between ascending and descending pass SSS retrievals from the Aquarius satellite. However, the diurnal signal can be masked by errors in the geophysical corrections used in processing the Aquarius measurements and in other spurious sources such as radio frequency interference. In this study we quantify the expected range of diurnal salinity variations using a model developed for predicting diurnal sea surface temperature variations and search for regions where Aquarius may detect a true diurnal SSS signal. We also use an independent approach based on the near surface salinity balance and observed precipitation by isolating regions where the surface buoyancy input suppresses vertical mixing. This study should shed light on the processes contributing to upper ocean salinity variations, and provide a better target for assessing remaining errors in the Aquarius processing algorithms.