Advances in Earth Science ›› 2014, Vol. 29 ›› Issue (10): 1167-1174. doi: 10.11867/j.issn.1001-8166.2014.10.1167

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Long-term Impact of Geothermal Heat Flux on the Deep Ocean Temperature and Circulation

Zedong Liu 1( ), Xiuquan Wan 1, 2( ), Fukai Liu 1   

  1. 1. Department of Oceanography, College of Physical and Environmental Oceanography, Ocean University of China, Qingdao 266100, China
    2.Physical Oceanography Laboratory of the Ministry of Education, Ocean University of China, Qingdao 266100, China
  • Online:2014-10-20 Published:2014-10-20

Zedong Liu, Xiuquan Wan, Fukai Liu. Long-term Impact of Geothermal Heat Flux on the Deep Ocean Temperature and Circulation[J]. Advances in Earth Science, 2014, 29(10): 1167-1174.

Although Geothermal Heat Flux (GHF) through the seafloor has a trivial contribution to the oceanic heat budget balance, and is excluded in the development of most climate models, its potential effect on long-term ocean circulation and climate change may not be ignored. The GHF could be as a continuously buoyancy forcing and changes ocean stratification, affects the ocean temperature distribution as well as the ocean circulation and other hydrological elements, and further affects the chemical properties of seawater, carbon and nitrogen cycle and biological distribution, etc. Here we presented a 5000-year sensitivity experiment with the Community Earth System Model (CESM) by adding geothermal heat flux of 1 W/m2 at the seafloor near the Mid-ocean ridge. The numerical results suggested that the long-term impact of GHF on deep ocean circulation and physical characters was not to be neglected. Comparing to the control experiment, the local geothermal heating contributed to an overall warming of deep waters (between 3 000~3 500 m) by 0.4 ℃, with the maximum warming of 0.85 ℃ at the southeast Pacific Ocean. It then further decreased the stability of the water column, enhanced the formation rates of North Atlantic Deep Water (NADW) and Antarctic Bottom Water (AABW), and strengthend the corresponding Meridional Overturning Circulations (MOC) by 1.7 Sv and 3.7 Sv, respectively. In the sensitivity experiment, the penetration depth of NADW also increased to the depth of 3 000~3 500 m, which was closer to observations. At the deep water formation region of North Atlantic and Southern Ocean, the GHF-induced warming signals could even reach to sea surface.

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