4:30 PM - 4:45 PM
[MIS18-09] Evaluation of the roles of surface flux changes in the Atlantic meridional overturning circulation during the last glacial maximum
★Invited Papers
Keywords:Atlantic meridional overturning circulation, last glacial maximum, OGCM, PMIP
Proxy data suggest that the Atlantic Meridional Overturning Circulation (AMOC) was shallower during the Last Glacial Maximum (LGM) than at present. On the other hand, many climate models participating in the Paleoclimate Model Intercomparison Project (PMIP) show a stronger and deeper AMOC, and there are significant differences among the models. The mechanisms of how the glacial climate changes the AMOC have been studied mainly in terms of changes in wind stress and temperature, but these mechanisms have not been discussed in a comparative manner.
In this study, we conducted numerical simulations to evaluate the relative impact of changes in sea surface boundary conditions on the AMOC during the glacial period by organizing them into three categories: thermal conditions, wind stress, and freshwater fluxes. The changes in sea surface boundary conditions at the LGM were obtained from the output of various PMIP models, and the changes in thermal conditions, wind stress, and freshwater fluxes were separately applied to a ocean general circulation model to investigate how they change the AMOC. The results showed that the thermal conditions of the LGM weakened the AMOC, while wind stress and freshwater flux strengthened it. In particular, the cooling of the Southern Ocean had a significant effect on the weakening of the AMOC through the densification of Antarctic Bottom Water, and the different degrees of cooling of the Southern Ocean among the models caused a considerable variation in the strength of the AMOC.
In this study, we conducted numerical simulations to evaluate the relative impact of changes in sea surface boundary conditions on the AMOC during the glacial period by organizing them into three categories: thermal conditions, wind stress, and freshwater fluxes. The changes in sea surface boundary conditions at the LGM were obtained from the output of various PMIP models, and the changes in thermal conditions, wind stress, and freshwater fluxes were separately applied to a ocean general circulation model to investigate how they change the AMOC. The results showed that the thermal conditions of the LGM weakened the AMOC, while wind stress and freshwater flux strengthened it. In particular, the cooling of the Southern Ocean had a significant effect on the weakening of the AMOC through the densification of Antarctic Bottom Water, and the different degrees of cooling of the Southern Ocean among the models caused a considerable variation in the strength of the AMOC.