Changing Atmospheric Blocking

长期以来，大气阻塞一直被认为是数值天气和气候模式的主要弱点之一。许多气候科学家担心，模型无法准确模拟阻塞事件，然而，如果阻塞行为发生变化，将对区域气候产生重大影响。持续阻挡的反气旋导致夏季极端热浪和干旱，冬季持续寒冷。这些事件在欧洲最近几个极端季节的发生中起到了重要作用。该项目将对阻塞在最先进的气候模型中的模拟情况进行全面评估。我们将评估这些模型再现我们在观测中看到的阻塞发生的能力，我们还将首次提供我们发现的任何模型偏差的时间尺度的诊断。基于不同气候模型的预测，我们将评估阻塞可能如何改变，以应对未来的温室气体强迫，以及我们应该对这些预测有多大的信心。对于欧洲，将得出结论，未来可能会发生夏季极端热浪和干旱，冬季可能出现寒流。

Atmospheric blocking has long been considered one of the key weaknesses of numerical weather and climate models. Many climate scientists are concerned that models are not able to accurately simulate blocking events, and yet if there were to be a change in blocking behaviour this would have a large impact on regional climate. Persistent blocking anticyclones lead to extreme heatwaves and drought in summer and extended cold spells in winter. Such events have been instrumental in leading to several recent extreme seasons in Europe. This project will provide a comprehensive assessment of how well blocking is simulated in state of the art climate models. We will evaluate the ability of the models to reproduce the occurrence of blocking that we see in observations, and we will also for the first time provide a diagnosis of which timescales are responsible for any model biases that we find. Based on the projections of the different climate models we will produce an assessment of how blocking may change in response to future greenhouse gas forcing, and how much confidence we should have in these projections. For Europe, conclusions will be drawn for the likely future occurrence of extreme heatwaves and drought in summer and cold spells in winter.