A “Triple Sea-Ice State” Mechanism for the Abrupt Warming and Synchronous Ice Sheet Collapses During Heinrich Events
A “Triple Sea-Ice State” Mechanism for the Abrupt Warming and Synchronous Ice Sheet Collapses During Heinrich Events
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海因里希事件期间突然变暖和同步冰盖崩塌的“三重海冰状态”机制
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发表时间：
2004
期刊：
影响因子：
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通讯作者：
E. Tziperman
中科院分区：
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作者：
Y. Kaspi;R. Sayag;E. Tziperman
[1]海冰覆盖的突然，开关式的变化被认为是大幅度突然变暖的一种机制，这种机制似乎发生在每一次海因里希事件之后。海冰的变化也被用来解释冰川排放时比周围环境更冷的冰川条件。在这一机制下，由于海冰快速融化，通过强烈的海冰反射和绝热反馈使大气变暖，从而发生了突变增暖事件。这种突然的海冰变化也可以解释在Dansgaard-Oeschger事件期间观察到的变暖。海冰的变化是由弱（5 Sv的顺序）的温盐环流（THC）冰川放电的响应。因此，这项工作的要点是，海冰可以被认为是一个非常有效的放大器的一个弱THC的变化，解释了格陵兰岛的温度突变。一些代理记录表明，北大西洋不同冰盖的同步冰盖崩溃是可能的，通过不同冰盖之间的弱耦合引起的海冰变化引起的大气温度变化。这种弱耦合可能导致不同冰盖的“非线性锁相”，从而同步放电。它表明，相位锁定也可能导致“前兆”冰川放电事件之前，从较小的冰盖劳伦特冰盖放电。这一机制中的前兆事件是劳伦泰德冰盖主要冰川排放的结果，而不是原因。
[1] Abrupt, switch-like, changes in sea ice cover are proposed as a mechanism for the large-amplitude abrupt warming that seemed to have occurred after each Heinrich event. Sea ice changes are also used to explain the colder-than-ambient glacial conditions around the time of the glacier discharge. The abrupt warming events occur in this mechanism, owing to rapid sea ice melting which warmed the atmosphere via the strong sea ice albedo and insulating feedbacks. Such abrupt sea ice changes can also account for the warming observed during Dansgaard-Oeschger events. The sea ice changes are caused by a weak (order of 5 Sv) response of the thermohaline circulation (THC) to glacier discharges. The main point of this work is therefore that sea ice may be thought of as a very effective amplifier of a weak THC variability, explaining the abrupt temperature changes over Greenland. Synchronous ice sheet collapses from different ice sheets around the North Atlantic, indicated by some proxy records, are shown to be possible via the weak coupling between the different ice sheets by the atmospheric temperature changes caused by the sea ice changes. This weak coupling can lead to a “nonlinear phase locking” of the different ice sheets which therefore discharge synchronously. It is shown that the phase locking may also lead to “precursor” glacier discharge events from smaller ice sheets before the Laurentide Ice Sheet discharges. The precursor events in this mechanism are the result rather than the cause of the major glacier discharges from the Laurentide Ice Sheet.