Meridional Atmospheric Heat Transport Constrained by Energetics and Mediated by Large-Scale Diffusion
Meridional Atmospheric Heat Transport Constrained by Energetics and Mediated by Large-Scale Diffusion
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DOI：
10.1175/jcli-d-18-0563.1
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发表时间：
2019-06-01
影响因子：
4.9
通讯作者：
Roe, Gerard H.
中科院分区：
文献类型：
--
作者：
Armour, Kyle C.;Siler, Nicholas;Roe, Gerard H.
经向大气热输送（AHT）已经通过三个广泛的观点进行了研究：一个动力学的观点，联系AHT的向极通量的湿静能（MSE）的大气运动;一个充满活力的观点，联系AHT的能量输入到大气中的顶部的大气辐射和地面热通量;和扩散的观点，代表AHT的向下梯度能量输送。这表明，这三个角度提供了互补的诊断的纬向AHT和温室气体强迫下的变化。当结合起来，充满活力的和扩散的观点提供了预测的见解：异常AHT的约束，以满足净能量需求的辐射强迫，辐射反馈，和海洋热吸收，反过来，暖化的纬向模式必须调整，以产生这些AHT的变化，这样做近似根据异常MSE的扩散。温度和MSE之间的关系对变暖模式施加了很强的约束，有利于极性放大。这些结论是支持使用扩散湿能量平衡模式（EBM），准确地预测综合大气环流模式（GCMs）内的纬向平均变暖和AHT的变化。一个干的扩散EBM预测类似的AHT变化，以满足相同的能量约束，但这样做是通过热带放大变暖与GCM的极性放大变暖模式的不一致。结果表明，极地放大变暖几乎是潮湿、扩散性大气对温室气体强迫反应的必然结果。在这种观点下，大气环流必须满足能量学约束下的净AHT。
Meridional atmospheric heat transport (AHT) has been investigated through three broad perspectives: a dynamic perspective, linking AHT to the poleward flux of moist static energy (MSE) by atmospheric motions; an energetic perspective, linking AHT to energy input to the atmosphere by top-of-atmosphere radiation and surface heat fluxes; and a diffusive perspective, representing AHT in terms downgradient energy transport. It is shown here that the three perspectives provide complementary diagnostics of meridional AHT and its changes under greenhouse gas forcing. When combined, the energetic and diffusive perspectives offer prognostic insights: anomalous AHT is constrained to satisfy the net energetic demands of radiative forcing, radiative feedbacks, and ocean heat uptake; in turn, the meridional pattern of warming must adjust to produce those AHT changes, and does so approximately according to diffusion of anomalous MSE. The relationship between temperature and MSE exerts strong constraints on the warming pattern, favoring polar amplification. These conclusions are supported by use of a diffusive moist energy balance model (EBM) that accurately predicts zonal-mean warming and AHT changes within comprehensive general circulation models (GCMs). A dry diffusive EBM predicts similar AHT changes in order to satisfy the same energetic constraints, but does so through tropically amplified warming-at odds with the GCMs' polar-amplified warming pattern. The results suggest that polar-amplified warming is a near-inevitable consequence of a moist, diffusive atmosphere's response to greenhouse gas forcing. In this view, atmospheric circulations must act to satisfy net AHT as constrained by energetics.