Simulated Spatiotemporal Response of Ocean Heat Transport to Freshwater Enhancement in North Atlantic and Associated Mechanisms |
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Authors: | Lei Yu Yongqi Gao |
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Institution: | 1,21 Nansen-Zhu International Research Center,Institute of Atmospheric Physics,Chinese Academy of Sciences,Beijing 100029,China2 Nansen Environmental and Remote Sensing Center/Bjerknes Centre for Climate Research,N-5006,Bergen,Norway |
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Abstract: | The Atlantic Meridional Overturning Circulation (AMOC) transports a large amount of heat to northern high latitudes, playing
an important role in the global climate change. Investigation of the freshwater perturbation in North Atlantic (NA) has become
one of the hot topics in the recent years. In this study, the mechanism and pathway of meridional ocean heat transport (OHT)
under the enhanced freshwater input to the northern high latitudes in the Atlantic are investigated by an ocean-sea ice-atmosphere
coupled model. The results show that the anomalous OHT in the freshwater experiment (FW) is dominated by the meridional circulation
kinetic and ocean thermal processes. In the FW, OHT drops down during the period of weakened AMOC while the upper tropical
ocean turns warmer due to the retained NA warm currents. Conversely, OHT recovers as the AMOC recovers, and the mechanism
can be generalized as: 1) increased ocean heat content in the tropical Southern Ocean during the early integration provides
the thermal condition for the recovery of OHT in NA; 2) the OHT from the Southern Ocean enters the NA through the equator
along the deep Ekman layer; 3) in NA, the recovery of OHT appears mainly along the isopycnic layers of 24.70–25.77 below the
mixing layer. It is then transported into the mixing layer from the “outcropping points” in northern high latitudes, and finally
released to the atmosphere by the ocean-atmosphere heat exchange. |
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Keywords: | the Atlantic meridional overturning circulation meridional ocean heat transport freshwater experiment |
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