Purpose of Review

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.

Recent Findings

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.

Summary

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.

中文翻译：

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阻塞及其对气候变化的反应。

审查目的

大气阻塞事件代表了中纬度地区一些影响最大的天气模式，但它们经常成为未来气候预测的关注点。尽管气候模型之间关于阻塞减少的相对较好的一致性，但对预测的未来阻塞变化的信心很低。这是由于缺乏全面的阻塞理论以及模型普遍低估了阻塞的发生。本文回顾了气候变化下关于阻塞的知识状况，旨在为相关领域的工作人员提供一个概述。

最近的发现

已经确定了几种可以在数值模型中改进阻塞的途径，尽管完全可靠的模拟仍然难以捉摸（至少，超过几天的准备时间）。因此，模型开始提供一些有用的信息，说明阻塞及其影响在未来可能如何变化，尽管需要更深入地了解正在发挥作用的过程，以增加对模型预测的信心。对于阻塞的发生、维持和衰减最重要的过程以及我们对大气动力学的理解的进展，例如在非绝热过程的作用方面，仍然存在重大不确定性，继续为建模和预测工作提供信息。

概括

“阻塞”一词涵盖了各种各样的天气模式，因此已经开发了一系列令人眼花缭乱的指标来识别事件。因此，在使用几种不同的方法找到结果之前，结果不被认为是完全可信的。这种稳健结果的例子是模型对阻塞的低估，以及未来发生率的总体下降，尽管存在复杂的区域和季节性变化。相比之下，最近历史时期的半球阻塞趋势没有得到不同方法的支持，自然变率可能会在未来几十年内主导区域变化。