Search Results (2)

Recent studies have suggested that there is a dynamic connection between the Atlantic Meridional Overturning Circulation (AMOC) and the North Atlantic subpolar gyre (SPG). This modeling study uses a fully coupled atmosphere–ocean–sea ice Earth system model to investigate the SPG dynamics throughout the past twenty-two thousand years. We found that the variations in the SPG and AMOC strength are synchronized. Consequently, during cold events in the Northern Hemisphere, the SPG strength declined simultaneously with the AMOC strength and with shallower mixed layer depths, which reduced the northward meridional heat transport and increased Atlantic sea ice coverage. Full article

The Southern Ocean waters exchange freshwater, nutrients, carbon, heat, and salt to the Equator and influence the global carbon budget. Therefore, it is essential to understand the variations in Southern Ocean circulation during the last deglacial period to comprehend its changes with climate change. To understand the spread of the Southern Ocean Antarctic Intermediate and Subantarctic Mode Waters during the last deglaciation (from about 19 to 11 thousand years before the present (kyr BP)), this modeling study employs a synchronously coupled general circulation model. The results show that the Southern Hemisphere’s low-level winds overlap with the zone of maximum mixed layer depth, signifying the influence of westerlies in the Southern Ocean waters. The results also indicate that the Southern Ocean Antarctic Intermediate and Subantarctic Mode Waters are fresher, warmer, and about 2.4 times deeper during the early Holocene compared to Heinrich-1. The model simulated the Antarctic sea ice edge (grid points in the ice model have a sea ice concentration above ten percent) overlapping with the poleward edge of the Antarctic Intermediate Waters, and the Southern Ocean mixed layers. Additionally, the simulated quasi-permanent Antarctic sea ice edge (grid points in the ice model have a sea ice concentration above eighty percent) and the surface distribution of Antarctic Intermediate and Subantarctic Mode Waters shifted poleward by about 5° and 10°, respectively, during the early Holocene compared to the Heinrich-1. Therefore, this study highlights a close linkage between the Southern Ocean Antarctic Intermediate and Subantarctic Mode Waters with the Antarctic sea ice distribution throughout the last deglacial period. Full article