Climatic variability of spice injection in the upper ocean of the southeastern Pacific during 1992-2016.

Seasonal-to-decadal variability of spice injection in the upper ocean of the subtropical southeastern Pacific (SEP) is investigated using 3-day and 0.25-degree simulations spanning from 1992 to 2016 in the Consortium for Estimating the Circulation and Climate of the Ocean (ECCO). The spice injection refers to convective mixing through which saline water in the mixed layer is injected into the interior to generate positive temperature and salinity anomalies or potential spicity anomaly (PSA). Results show that the spice injection occurs during the winter when the mixed layer in the SEP is deep and a positive PSA appears around the bottom of the mixed layer and in the interior. The interior PSA is found to experience significant interannual variability, which is well correlated with winter mixed layer depth (MLD), with more interior PSA corresponding to deeper MLD. During a strong winter of injection, the interior potential spicity change rate can reach up to ~0.006 kg·m^-3·day^-1 and the gain of potential spicity in the interior ~0.2 kg·m^-3 over the SEP region. The decadal variability of interior PSA in the SEP has a significant negative correlation to Interdecadal Pacific Oscillation (IPO), with larger (smaller) PSA during negative (positive) IPO period.