Meetings: Documents

Diurnal Sea Surface Salinity Variation Detection in Aquarius Data
[11-Nov-2014] Fine, E., Bryan, F., and Large, W.
Presented at the 2014 Aquarius/SAC-D Science Team Meeting
Small, but measurable, diurnal variations in sea surface salinity (SSS) have been observed at a few select locations with adequate in situ instrumentation. These variations result primarily from imbalances on diurnal timescales 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 true diurnal signal can be masked by errors in the geophysical corrections (e.g. galactic reflection) used in processing the Aquarius measurements and other spurious sources such as radio frequency interference. In this study we quantify the expected range of diurnal salinity variations on a global scale using an extension of a model developed for predicting diurnal sea surface temperature variations. Based on this guidance, we search for regions where Aquarius may be detecting 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 is such as to suppress vertical mixing. This study should help shed light on the processes contributing to upper ocean salinity variations, as well as provide a better target for assessing remaining errors in the Aquarius processing algorithms.