Note that the deeper salinity anomalies below about
600 dbar are not as coherent as their respective temperature
anomalies. This is due to the mean vertical
salinity gradients being very weak at depth (Fig. 1b).
Hence, any vertical motion will advect water of only
slightly different salinity to any given level, leading to
a small amplitude anomaly. Nonetheless, under the assumption
that the subsurface temperature and salinity
anomalies are due to vertical advection, in the upwelling
and downwelling parts of a Kelvin wave, the implied