Restoring and flux adjustment in simulating variability of an idealized ocean

Abstract

[1] Multi-century model runs are used to investigate the impact of restoring and flux adjustment on the variability of an idealized Atlantic Ocean forced by net atmospheric heat flux possessing decadal and multi-decadal variability. Restoring suppresses simulated modes of variability, causes phase shifts, and modifies nonlinear relations in the model. Flux adjustment has little effect on the water temperature variability, however it suppresses low-frequency variability of the meridional overturning circulation and causes a phase shift of multi-decadal mode of the meridional heat transport. An important effect of flux adjustment is that it may misrepresent physical mechanisms substituting, for example, dynamically-driven meridional heat transport by equivalent amount of heat supplied locally, though surface heat fluxes. We conclude that restoring provides improper framework for simulation of climate variability. Flux adjustment is less damaging, however, it modulates internal modes of variability in ways not fully understood.