Sea Surface Salinity Subfootprint Variability from a Global High-resolution Model
[18-Feb-2020] Bingham, F., D'Addezio, J.M., Fournier, S., Zhang H., and Ulfsax, K.
Presented at the 2020 Ocean Sciences Meeting
We have studied the subfootprint variability (SFV) of sea surface salinity (SSS) using the LLC4320 version of the MITgcm, a very high-resolution (1/48°) global simulation. SFV is the weighted standard deviation within the footprint of an SSS satellite like Aquarius or SMAP. SFV was studied as a function of footprint size and of space and time. It was found to be large in areas of strong frontal zones such as the Gulf Stream, Antarctic front and Brazil-Malvinas Confluence. SFV also tends to be larger where rainfall is heavy. It was found to have a seasonal and hemispheric component, being generally larger in the southern hemisphere and summer than the northern hemisphere and winter. For a 100 km footprint, the most likely values of SFV are (0.05, 0.06, 0.03, 0.05) for (southern summer, northern summer, southern winter, northern summer) respectively. Outlier high values were much more likely in summer than in winter. SFV follows a power law relationship with footprint size, increasing as ~s0.7, where s is the footprint size.