Climate and tropical cyclone activity: A new model downscaling approach
Climate and tropical cyclone activity: A new model downscaling approach
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DOI：
10.1175/jcli3908.1
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发表时间：
2006-10-01
影响因子：
4.9
通讯作者：
Emanuel, Kerry
中科院分区：
文献类型：
--
作者：
Emanuel, Kerry
虽然迫切需要了解和预测热带气旋对气候变化的反应，但目前的全球气候模型过于粗糙，无法在必要的程度上模拟热带气旋的强度，而且它们模拟成因的能力也值得怀疑。由于这些原因，一个“降尺度”的方法来模拟气候变化对热带气旋的影响是可取的。这里介绍了一种新的降尺度方法，包括生成一个大的合成风暴路径，其统计数据与气候模式的大尺度环流相一致，然后运行一个确定性的，耦合的热带气旋模式沿着每个路径，大气和上层海洋热力学条件取自全球气候模式。作为这一方向的第一步，本文探讨了热带气旋的大样本的强度的潜在强度，切变和海洋混合层深度的变化的敏感性，固定其他变量，包括风暴成因的时空概率分布。结果表明，10%的潜在强度增加导致65%的“功率耗散指数”，在其生命周期内产生的热带气旋的机械能的总量的措施增加。这与在过去50年中观察到的功耗增加是一致的。风暴受环境风切变或海洋混合层深度的等效分数变化的影响较小。
While there is a pressing need to understand and predict the response of tropical cyclones to climate change, global climate models are at present too coarse to resolve tropical cyclones to the extent necessary to simulate their intensity, and their ability to simulate genesis is questionable. For these reasons, a "downscaling" approach to modeling the effect of climate change on tropical cyclones is desirable. Here a new approach to downscaling is introduced that consists of generating a large set of synthetic storm tracks whose statistics are consistent with the large-scale general circulation of the climate model, and then running a deterministic, coupled tropical cyclone model along each track, with atmospheric and upper-ocean thermodynamic conditions taken from the global climate model. As a first step in this direction, this paper explores the sensitivity of the intensity of a large sample of tropical cyclones to changes in potential intensity, shear, and ocean mixed layer depth, fixing other variables, including the space-time probability distribution of storm genesis. It is shown that a 10% increase in potential intensity leads to a 65% increase in the "power dissipation index," a measure of the total amount of mechanical energy generated by tropical cyclones over their life spans. This is consistent with the observed increase of power dissipation over the past 50 yr. Storms are somewhat less influenced by equivalent fractional changes in environmental wind shear or ocean mixed layer depth.