전구 해양순환에 미치는 해빙의 효과

Abstract

The effects of sea ice on oceanic circulation are investigated using the global Ocean General Circulation Model (OGCM). Two different cases of numerical experiment (experiment with and without ice) are performed to evaluate the impacts of sea ice on the global ocean. An additional experiment is conducted to investigate meltwater effects on the global ocean circulation by increasing the runoff over the north of 65°N (without ice).

The OGCM used in this study is the Modular Ocean Model version 4.1 (MOM4p1) with 1°horizontal resolution and 50 vertical levels. GM neutral density diffusion scheme is adopted for horizontal mixing and K-Profile scheme is used for vertical mixing. Corrected CORE version 2 – Normal Year Forcing are used to calculate heat, salt and momentum fluxes with a bulk formula at the sea surface without any relaxation of SST and SSS.

It is widely known that decrease of sea ice coverage weakens the strength of the thermohaline circulation (THC) because the ice meltwater intensifies stratification of water column at the deep water formation region.

In this study, however, results from experiment without ice show significant increases in the deep water formation due to enhanced deep convection with strong oceanic heat loss by getting rid of the insulation effect of sea ice. Consequently, these lead to the strengthened THC.

Furthermore, the simulated pattern of the Arctic Ocean circulation is significantly influenced by the Arctic halocline distribution. It suggests that the Arctic fresh water content and the strength of vertical mixing are important to control the behavior of the Arctic Ocean circulation.