Woollings Tim, Barriopedro David, Methven John, Son Seok-Woo, Martius Olivia, Harvey Ben, Sillmann Jana, Lupo Anthony R, Seneviratne Sonia
1Department of Physics, Atmospheric, Oceanic and Planetary Physics, University of Oxford, Parks Rd, Oxford, OX1 3PU UK.
2Instituto de Geociencias (IGEO), Consejo Superior de Investigaciones Científicas - Universidad Complutense de Madrid (CSIC-UCM), Madrid, Spain.
Curr Clim Change Rep. 2018;4(3):287-300. doi: 10.1007/s40641-018-0108-z. Epub 2018 Jul 20.
Atmospheric blocking events represent some of the most high-impact weather patterns in the mid-latitudes, yet they have often been a cause for concern in future climate projections. There has been low confidence in predicted future changes in blocking, despite relatively good agreement between climate models on a decline in blocking. This is due to the lack of a comprehensive theory of blocking and a pervasive underestimation of blocking occurrence by models. This paper reviews the state of knowledge regarding blocking under climate change, with the aim of providing an overview for those working in related fields.
Several avenues have been identified by which blocking can be improved in numerical models, though a fully reliable simulation remains elusive (at least, beyond a few days lead time). Models are therefore starting to provide some useful information on how blocking and its impacts may change in the future, although deeper understanding of the processes at play will be needed to increase confidence in model projections. There are still major uncertainties regarding the processes most important to the onset, maintenance and decay of blocking and advances in our understanding of atmospheric dynamics, for example in the role of diabatic processes, continue to inform the modelling and prediction efforts.
The term 'blocking' covers a diverse array of synoptic patterns, and hence a bewildering range of indices has been developed to identify events. Results are hence not considered fully trustworthy until they have been found using several different methods. Examples of such robust results are the underestimation of blocking by models, and an overall decline in future occurrence, albeit with a complex regional and seasonal variation. In contrast, hemispheric trends in blocking over the recent historical period are not supported by different methods, and natural variability will likely dominate regional variations over the next few decades.
大气阻塞事件是中纬度地区一些影响最为重大的天气模式，但在未来气候预测中，它们常常引发关注。尽管气候模型在阻塞现象减少方面的预测相对一致，但对于未来阻塞变化的预测信心不足。这是由于缺乏关于阻塞的全面理论，且模型普遍低估了阻塞事件的发生。本文综述了气候变化下有关阻塞的知识现状，旨在为相关领域的工作人员提供一个概述。
已经确定了几种可以在数值模型中改进阻塞现象模拟的途径，不过完全可靠的模拟仍然难以实现（至少在提前几天以上的时间范围内）。因此，模型开始提供一些关于阻塞现象及其影响在未来可能如何变化的有用信息，尽管需要更深入地理解其中的过程，以增强对模型预测的信心。关于阻塞的发生、维持和衰减最重要的过程仍存在重大不确定性，对大气动力学理解的进展，例如非绝热过程的作用，继续为建模和预测工作提供信息。
“阻塞”一词涵盖了各种各样的天气形势，因此已经开发出了一系列令人眼花缭乱的指数来识别这些事件。因此，在使用几种不同方法得到结果之前，这些结果不会被认为是完全可信的。这类可靠结果的例子包括模型对阻塞现象的低估，以及未来阻塞事件总体上的减少，尽管存在复杂的区域和季节变化。相比之下，不同方法并不支持近期历史时期阻塞现象的半球趋势，并且在未来几十年自然变率可能主导区域变化。
