摘要
虽然地球海底地热通量在全球热能收支平衡中所占的比例非常低,在目前的海洋气候模式开发中也并没有将其包含在内,但是由于海底地热通量可以持续改变海洋的浮力而影响海水层结,进而影响海洋温度分布以及环流等海洋水文要素,并且可以进一步影响海水的化学性质、碳氮的分布循环以及生物分布等,因此其对海洋环流和气候变化长期影响的潜在可能性仍不能完全排除。在通用地球系统耦合模式（CESM）的基础上,通过在全球大洋中脊区域持续加入1 W/m^2的地热通量的方式运行了长达5 000年的数值模拟实验,模式结果显示：海底地热通量对深层海洋的物理性质和全球海洋环流的长期影响是不可忽略的;受地热通量的局地加热效应影响,大洋深层3 000~3 500 m总体升温约0.4℃;在南大洋和北大西洋的深层水形成区域,海洋深层的增温信号可以影响到表层海洋。北大西洋深层水和南极底层水形成增强,并且模拟的北大西洋深层水的深度加深,更符合观测结果。
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 GH＇F 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 i 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.
出处
《地球科学进展》
CAS
CSCD
北大核心
2014年第10期1167-1174,共8页
Advances in Earth Science
基金
国家自然科学基金面上项目"天气噪声对大西洋经向翻转环流变异的作用"(编号:41276013)
国家自然科学基金创新群体项目"海洋动力过程的演变机理及其在气候变化中的作用(二期)"(编号:41221063)资助
关键词
地热通量
海洋模式
温度
海洋环流
气候变化
Geothermal Heat Flux
Ocean Model
Temperature
Ocean Circulation
Climate Change.
