The Steady-State Atmospheric Circulation Response to Climate Change-like Thermal Forcings in a Simple General Circulation Model
The Steady-State Atmospheric Circulation Response to Climate Change-like Thermal Forcings in a Simple General Circulation Model
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DOI：
10.1175/2010jcli3228.1
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发表时间：
2010-07-01
影响因子：
4.9
通讯作者：
Heikes, Ross
中科院分区：
文献类型：
--
作者：
Butler, Amy H.;Thompson, David W. J.;Heikes, Ross
利用一个简单的大气环流模式研究了定常对流层外大气对热力强迫的响应。热力强迫定性地模拟了人类活动引起的气候变化的三个关键方面：热带对流层变暖、极地平流层变冷和极地地表变暖。主要的新发现如下：1）热带对流层的变暖在模式中驱动了两个强大的响应：热带对流层外风暴路径的极向移动和平流层布鲁尔-多布森环流减弱。前者的结果表明，热带对流层的加热在政府间气候变化专门委员会（IPCC）级气候变化模拟中发现的风暴路径向极向收缩中起着重要作用;后一个结果与以前大多数气候变化实验中发现的布鲁尔-多布森环流趋势相反。极地平流层的冷却也驱动了热带风暴路径的向极移动。对流层的响应在很大程度上是一致的，在以前的研究中发现，但它被证明是非常敏感的水平和深度的强迫。在平流层中，布鲁尔-多布森环流在中纬度减弱，但在高纬度由于极涡侧翼的强烈向极热通量而增强。3）极面变暖驱动风暴路径向赤道移动。风暴轴对极地变暖的响应与对热带对流层加热的响应相反;因此，北极地区的大幅变暖可能会减弱北方半球风暴路径对热带加热的响应。4）对流层和平流层对这里考虑的所有热力强迫的响应的迹象对基本状态的季节变化是稳健的，但在春分和冬季条件下，反应的幅度和细节表现出明显的差异。此外，响应表现出显着的非线性，在这个意义上说，多个热强迫同时施加的响应是定量不同的相同的强迫单独施加的响应之和。因此，模式对给定热力强迫的响应显然取决于施加到模式上的其他热力强迫。
The steady-state extratropical atmospheric response to thermal forcing is investigated in a simple atmospheric general circulation model. The thermal forcings qualitatively mimic three key aspects of anthropogenic climate change: warming in the tropical troposphere, cooling in the polar stratosphere, and warming at the polar surface. The principal novel findings are the following:1) Warming in the tropical troposphere drives two robust responses in the model extratropical circulation: poleward shifts in the extratropical tropospheric storm tracks and a weakened stratospheric Brewer-Dobson circulation. The former result suggests heating in the tropical troposphere plays a fundamental role in the poleward contraction of the storm tracks found in Intergovernmental Panel on Climate Change (IPCC)-class climate change simulations; the latter result is in the opposite sense of the trends in the Brewer-Dobson circulation found in most previous climate change experiments.2) Cooling in the polar stratosphere also drives a poleward shift in the extratropical storm tracks. The tropospheric response is largely consistent with that found in previous studies, but it is shown to be very sensitive to the level and depth of the forcing. In the stratosphere, the Brewer-Dobson circulation weakens at midlatitudes, but it strengthens at high latitudes because of anomalously poleward heat fluxes on the flank of the polar vortex.3) Warming at the polar surface drives an equatorward shift of the storm tracks. The storm-track response to polar warming is in the opposite sense of the response to tropical tropospheric heating; hence large warming over the Arctic may act to attenuate the response of the Northern Hemisphere storm track to tropical heating.4) The signs of the tropospheric and stratospheric responses to all thermal forcings considered here are robust to seasonal changes in the basic state, but the amplitude and details of the responses exhibit noticeable differences between equinoctial and wintertime conditions. Additionally, the responses exhibit marked non-linearity in the sense that the response to multiple thermal forcings applied simultaneously is quantitatively different from the sum of the responses to the same forcings applied independently. Thus the response of the model to a given thermal forcing is demonstrably dependent on the other thermal forcings applied to the model.