The ocean's role in setting the mean position of the Inter-Tropical Convergence Zone
The ocean's role in setting the mean position of the Inter-Tropical Convergence Zone
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DOI：
10.1007/s00382-013-1767-z
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发表时间：
2014-04-01
期刊：
影响因子：
4.6
通讯作者：
McGee, D.
中科院分区：
文献类型：
--
作者：
Marshall, J.;Donohoe, A.;McGee, D.
通过对观测资料和耦合气候模拟的研究，认为赤道以北热带辐合带（ITCZ）的平均位置是海洋环流向北输送热量的结果。观测表明，大气顶部的半球净辐射气候强迫几乎完全对称于赤道，因此穿过赤道的总热量输送（大气加上海洋）很小（向北约为0.2 PW）。然而，由于大西洋的纬向翻转环流，海洋向北携带的热量明显多于赤道（0.4 PW量级）。有两个主要后果。首先，大气热量输送是向南穿过赤道进行补偿（向南0.2 PW），导致ITCZ向赤道以北移动。第二，大气层，实际上海洋，在北方半球比南半球稍微温暖（大约2摄氏度）。这导致北方半球由于相对温暖而比南半球发出的长波辐射略多，支持了赤道耦合系统向北的小热量输送。最后，耦合的性质的问题说明通过研究的大气-海洋-冰模拟在理想化的设置aquaplanet，解决工作中的关键过程。
Through study of observations and coupled climate simulations, it is argued that the mean position of the Inter-Tropical Convergence Zone (ITCZ) north of the equator is a consequence of a northwards heat transport across the equator by ocean circulation. Observations suggest that the hemispheric net radiative forcing of climate at the top of the atmosphere is almost perfectly symmetric about the equator, and so the total (atmosphere plus ocean) heat transport across the equator is small (order 0.2 PW northwards). Due to the Atlantic ocean's meridional overturning circulation, however, the ocean carries significantly more heat northwards across the equator (order 0.4 PW) than does the coupled system. There are two primary consequences. First, atmospheric heat transport is southwards across the equator to compensate (0.2 PW southwards), resulting in the ITCZ being displaced north of the equator. Second, the atmosphere, and indeed the ocean, is slightly warmer (by perhaps 2 A degrees C) in the northern hemisphere than in the southern hemisphere. This leads to the northern hemisphere emitting slightly more outgoing longwave radiation than the southern hemisphere by virtue of its relative warmth, supporting the small northward heat transport by the coupled system across the equator. To conclude, the coupled nature of the problem is illustrated through study of atmosphere-ocean-ice simulations in the idealized setting of an aquaplanet, resolving the key processes at work.