Atlantic Ocean Circulation During the Last Glacial Maximum Simulated by PMIP3 Climate Models

MUGLIA, JUAN; SCHMITTNER, ANDREAS

Workshop; PMIP Ocean Workshop 2013: Understanding Changes since the Last Glacial Maximum; 2013

Computer simulated meridional streamfunction data were obtained from the GISS, MIROC, CCSM4, CNRM, Fgoals, MPI and MRI PMIP3 models, from the LGM and the Pre-Industrial Control data sets. We evaluated the difference between both time periods, by taking 50 year averages, and subtracting, foreach model, the averaged values of the LGM and Pre-Industrial Control streamfunction. We observe an increase in the intensity of the Atlantic Meridional Overturning Circulation (AMOC) in all the models studied, which averaged over all of them gives a 40% increase. This result contradicts some previous inferences based onpaleoclimate data from the sea floor (McManus, Francois, Gherardi, Keigwin, & Brown-Leger, 2004). To investigate the processes governing the contrast found between the LGM and Control streamfunctions, we study the simulated density gradient across the Florida Straits, motivated by the observational results of (Lynch-Stieglitz, Curry, & Slowey, 1999) who suggest a reduction in that variable for the LGM. Furthermore, we study the response of the UVic Model to changes in different forcings according to the range of estimates for the LGM, in order to infer the relevance of the different variables as drivers of change in the AMOC.