Another reason for elevated standard deviations in the
WOA-derived time series could be the data distribution in the
World Ocean Data Base (WOD01: Conkright et al., 2001).
Salinity data are far less numerous than temperature data.
Large differences in the number of observations in neighbouring
cells, or different bias towards different seasons, can
potentially lead to differently weighted means that can result
in unrealistic salinity gradients. Strong seasonal affects at
the depth of AAIW are unlikely, but data density decreases
rapidly with depth, and means from sparse data can produce
distortions of the field