Float 3900103 (Fig. 12 top) spent nearly three years in
the equatorial region where the AAIW salinity minimum is
weakly defined and gradients are extremely small. Its salinity
record generally agrees well with WOA climatology, but the
salinity field still contains frontal structures at a very large
distance from the source of the salinity minimum: Around
day 400 the float clearly crossed from a region characterized
by a minimum salinity of 35.555 to a region where the salinity
minimum is closer to 35.563. The change is just large
enough to fall outside instrumental detection limits and occurs
at a point where the WOA climatology indicates an increase
in the minimum salinity as well