High-latitude climate change in a global coupled ocean-atmosphere-sea ice model with increased atmospheric CO2
High-latitude climate change in a global coupled ocean-atmosphere-sea ice model with increased atmospheric CO2
复制标题
全球海洋-大气-海冰耦合模型中大气二氧化碳增加的高纬度气候变化
DOI：
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发表时间：
1996
期刊：
影响因子：
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通讯作者：
G. Meehl
中科院分区：
文献类型：
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作者：
W. Washington;G. Meehl
一个全球大气环流模式(GCM)与一个具有动力和热力海冰的全球1度、20层海洋GCM耦合在一起，与二氧化碳以每年1%的速度复合75年(大约70年二氧化碳增加一倍)。实验中没有使用磁通校正。CO2倍增时全球平均地表气温升高3.8℃。北冰洋中等深度的暖次表层大西洋层主要由模式中西斯匹茨卑尔根海流的下沉和入侵以及观测所维持。随着模式中二氧化碳的增加，较温暖的表层水侵入大西洋层的上部，在200米至400米的深度产生了模式中的异常变暖。这类似于最近在北极观测到的深度附近的异常暖层。随着气候变暖和海冰消退，新露出的水面上的低云增加。然而，由于海冰融化而导致的地表反照率下降，大大抵消了这些地区云反照率的增加。这导致了北极地区行星反照率的净减少，这有助于强烈的冰反照率反馈和该模型相对较高的灵敏度。
A global atmospheric general circulation model (GCM) coupled to a global 1-degree, 20-level ocean GCM with dynamic and thermodynamic sea ice is integrated with CO2 increasing at 1% per year compounded for 75 years (CO2 doubles at about year 70). Flux correction is not used in the experiment. The increase of globally averaged surface air temperature at the time of CO2 doubling is 3.8°C. The warm subsurface Atlantic layer at intermediate depths in the Arctic is maintained mainly by the sinking and intrusion of water from the West Spitsbergen Current in the model and the observations. With increased CO2 in the model, the warmer surface waters are intruded into the upper portion of the Atlantic layer producing an anomalous warming in the model at depths between 200 and 400 m. This resembles an anomalous warm layer near those depths recently observed in the Arctic. As the climate warms and sea ice retreats, low clouds increase over the newly exposed water. Yet the consequent increase of cloud albedo over these regions is more than compensated for by the decrease of surface albedo due to the melting of sea ice. This produces a net decrease of planetary albedo in the Arctic that contributes to a strong ice-albedo feedback and the comparatively high sensitivity of the model.