Sea Ice Loss, Water Vapor Increases, and Their Interactions with Atmospheric Energy Transport in Driving Seasonal Polar Amplification
Sea Ice Loss, Water Vapor Increases, and Their Interactions with Atmospheric Energy Transport in Driving Seasonal Polar Amplification
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DOI：
10.1175/jcli-d-23-0219.1
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发表时间：
2023-08
影响因子：
4.9
通讯作者：
Po-Chun Chung;N. Feldl
中科院分区：
文献类型：
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作者：
Po-Chun Chung;N. Feldl
与海冰损失相关的冰-水反馈有助于极地放大，而水汽反馈有助于热带放大地表变暖。然而，这些反馈并不是独立于大气能量传输的，这增加了复杂相互作用的可能性，可能会掩盖极地放大的驱动因素，特别是其在季节周期中的表现。在这里，我们应用辐射传输层次的理想化ISCA气候模式耦合到一个热力学海冰模型。气候响应和辐射反馈被分解为海冰损失的贡献，包括退缩和减薄，以及水汽变化的辐射效应。我们发现，夏季海冰退缩导致冬季极地放大通过海洋热量的吸收和释放，从而减少干能量输送减弱变暖的幅度。此外，海冰变薄被发现抑制夏季变暖和增强冬季变暖，另外有助于冬季放大。水汽辐射效应通过抵消效应产生季节对称的极区变暖：夏季半球水汽含量增加引起夏季水汽反馈，同时通过增加纬向水汽梯度加强冬季半球的潜热输送。这些结果揭示了海冰退缩和水汽增加引起的大气能量输送变化对季节性极地放大的重要性，阐明了这些物理过程之间的相互作用。
The ice-albedo feedback associated with sea ice loss contributes to polar amplification, while the water vapor feedback contributes to tropical amplification of surface warming. However, these feedbacks are not independent of atmospheric energy transport, raising the possibility of complex interactions that may obscure the drivers of polar amplification, in particular its manifestation across the seasonal cycle. Here, we apply a radiative transfer hierarchy to the idealized Isca climate model coupled to a thermodynamic sea ice model. The climate responses and radiative feedbacks are decomposed into the contributions from sea ice loss, including both retreat and thinning, and the radiative effect of water vapor changes. We find that summer sea ice retreat causes winter polar amplification through ocean heat uptake and release, and the resulting decrease in dry energy transport weakens the magnitude of warming. Moreover, sea ice thinning is found to suppress summer warming and enhance winter warming, additionally contributing to winter amplification. The water vapor radiative effect produces seasonally symmetric polar warming via offsetting effects: enhanced moisture in the summer hemisphere induces the summer water vapor feedback and simultaneously strengthens the winter latent energy transport in the winter hemisphere by increasing the meridional moisture gradient. These results reveal the importance of changes in atmospheric energy transport induced by sea ice retreat and increased water vapor to seasonal polar amplification, elucidating the interactions among these physical processes.