Specified dynamics scheme impacts on wave-mean flow dynamics, convection, and tracer transport in CESM2 (WACCM6)
Specified dynamics scheme impacts on wave-mean flow dynamics, convection, and tracer transport in CESM2 (WACCM6)
复制标题
指定动力学方案对 CESM2 (WACCM6) 中波平均流动力学、对流和示踪剂传输的影响
DOI：
10.5194/acp-2021-169
复制
发表时间：
2021
影响因子：
6.3
通讯作者：
S. Tilmes
中科院分区：
文献类型：
--
作者：
N. Davis;P. Callaghan;I. Simpson;S. Tilmes
摘要。指定的动力学方案是普遍存在的建模工具，用于隔离动力学和运输对化学天气和气候的作用。它们通常通过线性松弛将化学-气候模式的环流约束为再分析产品中的环流。然而，最近的研究表明，这些方案在模式之间造成了化学气候和经向环流的差异，并且不能准确地再现环流的趋势。在本研究中，我们对社区地球系统模式第2版，全大气社区气候模式第6版（CESM2 (WACCM6)）中指定的动力学方案进行了系统评估，该方案主动推动环流向参考气象方向发展。指定的动力学实验是在广泛的时间尺度和参考气象频率范围内进行的，模型的循环被推到它自己的自由运行输出——对指定的动力学方案的一个干净的测试。环流尺度误差与气象频率呈显著的负相关关系，对微推时间尺度的依赖较小。而示踪剂、示踪剂输运和对流质量通量的环流强度和误差与微推时间尺度呈显著的负相关。在尽可能高的参考气象频率下，12至24小时的微动时间尺度可以最大限度地减少示踪剂、云和环流的误差，甚至可以达到每个时间步更新一次参考气象的实际极限。剩余环流和涡旋混合将示踪误差整合并累积在其特征传输路径的末端，导致对流层上层/平流层下层和极地平流层的误差升高。即使在最理想的情况下，轻推方案引入的示踪器也存在不可忽略的误差。为了取得进一步的进展，未来发展更复杂的推动计划可能是必要的。
Abstract. Specified dynamics schemes are ubiquitous modeling tools for isolating the role of dynamics and transport on chemical weather and climate. They typically constrain the circulation of a chemistry-climate model to the circulation in a reanalysis product through linear relaxation. However, recent studies suggest that these schemes create a divergence in chemical climate and the meridional circulation between models and do not accurately reproduce trends in the circulation. In this study we perform a systematic assessment of the specified dynamics scheme in the Community Earth System Model version 2, Whole Atmosphere Community Climate Model version 6 (CESM2 (WACCM6)), which proactively nudges the circulation toward the reference meteorology. Specified dynamics experiments are performed over a wide range of nudging timescales and reference meteorology frequencies, with the model's circulation nudged to its own free-running output - a clean test of the specified dynamics scheme. Errors in the circulation scale robustly and inversely with meteorology frequency, and have little dependence on nudging timescale. However, the circulation strength and errors in tracers, tracer transport, and convective mass flux scale robustly and inversely with nudging timescale. A 12 to 24 hour nudging timescale at the highest possible reference meteorology frequency minimizes errors in tracers, clouds, and the circulation, even up to the practical limit of one reference meteorology update every timestep. The residual circulation and eddy mixing integrate tracer errors and accumulate them at the end of their characteristic transport pathways, leading to elevated error in the upper troposphere/lower stratosphere and in the polar stratosphere. Even in the most ideal case, there are non-negligible errors in tracers introduced by the nudging scheme. Future development of more sophisticated nudging schemes may be necessary for further progress.
主要火山喷发对平流层水蒸气的影响
影响因子：
6.3
作者：
Löffler;Brinkop;und Jöckel
通讯作者：
und Jöckel
影响因子：
5.2
作者：
M. Chipperfield;S. Dhomse;R. Hossaini;W. Feng;M. Santee;M. Weber;J. Burrows;J. Wild;D. Loyola-D.-Lo
通讯作者：
M. Chipperfield;S. Dhomse;R. Hossaini;W. Feng;M. Santee;M. Weber;J. Burrows;J. Wild;D. Loyola-D.-Lo