Stable “Waterbelt” climates controlled by tropical ocean heat transport: A nonlinear coupled climate mechanism of relevance to Snowball Earth
Stable “Waterbelt” climates controlled by tropical ocean heat transport: A nonlinear coupled climate mechanism of relevance to Snowball Earth
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热带海洋热传输控制的稳定“水带”气候：与雪球地球相关的非线性耦合气候机制
DOI：
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发表时间：
2015
期刊：
影响因子：
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通讯作者：
B. Rose
中科院分区：
文献类型：
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作者：
B. Rose
关于新元古代雪球地球事件的持续争论激发了对极冷气候的稳定性和滞后性的理论研究。一个耦合的大气-海洋-海冰环流模式（GCM）具有4个稳定的平衡，范围从0%到100%的冰覆盖，包括具有热带海冰的“带”状态。所有四种状态都是在当前日照和温室气体水平以及两种理想的海洋盆地配置下发现的。通过强烈而狭窄的风驱动的海洋翻转单元，向冰边缘提供大约100 W m−2的热量，从而稳定了水带的反照率反馈。这需要风、海洋环流和冰范围之间的三方反馈，其中环流随着冰边缘的斜压性向赤道方向移动。温跃层要浅得多，在热带地区露头。海冰到处被雪覆盖，季节性周期很短。在太阳常数中，水带状态跨越46 W m−2的范围，具有显著的滞后，并允许接近冰点的赤道表面温度。附加的背景由平板海洋GCM和扩散能量平衡模型提供，两者都具有规定的海洋热输运（OHT）。与完全耦合模式不同的是，这些模式只支持一个稳定的冰缘，其位置受制于OHT辐合向极方向快速减弱的区域。通过改变两种模式中OHT的大小和空间结构，可以发现不同气候（包括稳定带）的变化范围很大。提出了气候和冰范围对高温的敏感性的一些热力学论据。
Ongoing controversy about Neoproterozoic Snowball Earth events motivates a theoretical study of stability and hysteresis properties of very cold climates. A coupled atmosphere‐ocean‐sea ice general circulation model (GCM) has four stable equilibria ranging from 0% to 100% ice cover, including a “Waterbelt” state with tropical sea ice. All four states are found at present‐day insolation and greenhouse gas levels and with two idealized ocean basin configurations. The Waterbelt is stabilized against albedo feedback by intense but narrow wind‐driven ocean overturning cells that deliver roughly 100 W m−2 heating to the ice edges. This requires three‐way feedback between winds, ocean circulation, and ice extent in which circulation is shifted equatorward, following the baroclinicity at the ice margins. The thermocline is much shallower and outcrops in the tropics. Sea ice is snow‐covered everywhere and has a minuscule seasonal cycle. The Waterbelt state spans a 46 W m−2 range in solar constant, has a significant hysteresis, and permits near‐freezing equatorial surface temperatures. Additional context is provided by a slab ocean GCM and a diffusive energy balance model, both with prescribed ocean heat transport (OHT). Unlike the fully coupled model, these support no more than one stable ice margin, the position of which is slaved to regions of rapid poleward decrease in OHT convergence. Wide ranges of different climates (including the stable Waterbelt) are found by varying the magnitude and spatial structure of OHT in both models. Some thermodynamic arguments for the sensitivity of climate, and ice extent to OHT are presented.
影响因子：
5.3
作者：
R. Ewing;I. Eisenman;M. Lamb;Laura N. Poppick;A. Maloof;W. Fischer
通讯作者：
R. Ewing;I. Eisenman;M. Lamb;Laura N. Poppick;A. Maloof;W. Fischer