[ACG45-P04] Assessments of salinity impacts on SST using a linear inverse model
Keywords:Indian Ocean Dipole, Salinity variation, Linear inverse model
To address this issue, here we propose to apply a linear inverse model (LIM), which succinctly describes the evolution of tropical climate variations within a linear framework. We have first determined the linear operator of the LIM based on temperature and salinity anomalies in the tropical Indian Ocean derived from an ocean reanalysis product and carried out a long-term integration of the LIM as a reference experiment. It is found that our LIM reasonably reproduces the amplitude and spatial structure of the observed temperature and salinity anomalies associated with the IOD. Then, we have designed another LIM experiment without the coupling between temperature and salinity variations (referred as “T-S decoupled LIM”), by modifying the linear operator of the original LIM. A comparison of outputs from both LIM experiments reveals that the amplitude of the IOD in the T-S decoupled LIM is substantially stronger than that of the reference experiments. This suggests that the interactions between temperature and salinity act to reduce the amplitude of the IOD, consistent with our previous results based on dynamical approaches. Calculations of the growth rates of the IOD-related SST anomalies further confirmed the above idea. Our results imply that the LIM can be a powerful tool for understanding and diagnosing the salinity impacts on SST in a simple manner.