Reconstructing the subsurface ocean decadal variability using surface nudging in a perfect model framework ...

• Main Authors: Guilyardi, Eric, Swingedouw, Didier, Mignot, Juliette, Labetoulle, Sonia, Servonnat, Jérôme, Séférian, Roland
• Format: Text
• Language: English
• Published: Springer 2015
• Subjects: 530 Physics; Sea ice
• Online Access: https://dx.doi.org/10.7892/boris.61484; http://boris.unibe.ch/61484/

Initialising the ocean internal variability for decadal predictability studies is a new area of research and a variety of ad hoc methods are currently proposed. In this study, we explore how nudging with sea surface temperature (SST) and salinity (SSS) can reconstruct the threedimensional variability of the ocean in a perfect model framework. This approach builds on the hypothesis that oceanic processes themselves will transport the surface information into the ocean interior as seen in ocean-only simulations. Five nudged simulations are designed to reconstruct a 150 years ‘‘target’’ simulation, defined as a portion of a long control simulation. The nudged simulations differ by the variables restored to, SST or SST + SSS, and by the area where the nudging is applied. The strength of the heat flux feedback is diagnosed from observations and the restoring coefficients for SSS use the same time-scale. We observed that this choice prevents spurious convection at high latitudes and near sea-ice border when ...