ON THE FORMATION OF MERIDIONAL OVERTURNING CIRCULATION IN THE PACIFIC OCEAN DURING THE MIS31 INTERGLACIAL

Earth climate history has been punctuated by cold (glacial) and warm (inter-glacial) intervals associated with modification of the planetary orbit and subsequently changes in paleotopography.
During the Pleistocene epoch, the time interval between 1.8 million and 11,700 before present, remarkable episodes of warmer climates such as the Marine Isotope
Stage (MIS) 1, 5e, 11c, and 31 which occurred at 9, 127, 409, and 1080 ka, lead to changes in air temperature in the polar regions and substantial melting of polar glaciers.

Based on first ever multi-millennium coupled climate simulations of the Marine Isotope Stage 31 (MIS31), long-term oceanic conditions characteristic of this interval have been analyzed. Modeling experiments forced by modified West Antarctic Ice Sheet (WAIS) topography and astronomical configuration, demonstrated that substantial increase in the thermohaline flow and its associated northward heat transport in both Atlantic and Pacific oceans are predicted to occur during the MIS31. In the Atlantic these changes are driven by enhanced oceanic heat loss and increased water density. In the Pacific, anomalous atmospheric circulation leads to an overall increase of the water mass transport in the subtropical gyre, and drastically modified subtropical cell.Additional aspects related to the formation of the Pacific ocean MOC will be presented.

This study is sponsored by the Brazilian Antarctic Program Grant CNPq 407681/2013-2.