The Big Chill - Observing and modelling cold air outbreaks

在本项目中，您将使用从基于飞机的实地活动中收集的一些案例研究来调查冷空气爆发。你将以高分辨率运行英国气象局的统一模型（MetUM）来模拟这些情况，并利用详细的现场观测来挑战模式预测。您将测试各种新的模型参数化，例如，测试“混合”3D/1D湍流方案；测试云微物理参数化的新发展；和模拟云街（Liu et al.）。地球物理学报，2004)。MetUM是最先进的数值天气及气候预测模式，可用于业务天气预报、季节预报和各种尺度的气候模式。因此，您对MetUM的研究有望导致这些应用程序的直接改进。你也可以使用MetUM的“单列模型”版本，它运行起来更简单，允许受控的单点实验。观测数据包括来自GFDex的一个冷空气爆发案例（格陵兰流动畸变实验；Renfrew等人，Bull.）。阿米尔。Meteorol。Soc。（2008），其中飞机遵循拉格朗日“空气包裹”，从而可以准确地观察到热量和水分的来源和汇。它还包括ACCACIA项目（2013年3月在北极斯瓦尔巴群岛周围的海冰上空飞行）和PIKNMIX项目（在冰岛和英国之间的海上飞行）的几次冷空气爆发飞行。将选择几个案例研究进行更仔细的检查和模拟。你们还将有机会参加2018年3月以冰岛海和格陵兰海为重点的重大国际实地活动，届时将对冷空气爆发进行新的飞机和船舶边界层观测。对冰岛海的研究相对较少，但现在这种情况正在改变，因为我们发现它在从亚极地海洋向北大西洋产生和输送稠密水方面起着关键作用，而这一作用现在正受到北极海冰退缩的影响（Moore等人，Nat. Clim.）。变化,2015;参见https://theconversation.com/declining-winter-sea-ice-near-greenland-spells-cooler-climate-for-europe-42976)。这一实地运动将使我们在了解这些过程方面向前迈出相当大的一步，你们的贡献将有助于进一步了解冷空气暴发在这一关键区域发挥的作用。

In this project you will investigate cold-air outbreaks using a number of case studies gathered from aircraft-based field campaigns. You will run the Met Office's Unified Model (the MetUM) at high resolution to simulate these cases and make use of the detailed in-situ observations to challenge the model forecasts. You will test various new model parameterizations, for example, testing the 'blended' 3D/1D turbulence scheme; testing new developments in cloud microphysics parameterization; and simulating cloud streets (Liu et al. Geophysical Res. Lett. 2004). The MetUM is a state-of-the art numerical weather and climate prediction model, which is used for operational weather forecasting, seasonal forecasting and climate modelling on all scales. Consequently your research with the MetUM is expected to lead to direct improvements in these applications. You may also make use of a 'Single Column Model' version of the MetUM, which is simpler to run and allows controlled single point experiments. The observational data includes one cold-air outbreak case from GFDex (the Greenland Flow Distortion Experiment; Renfrew et al., Bull. Amer. Meteorol. Soc., 2008) in which the aircraft followed a Lagrangian 'air parcel', thus allowing sources and sinks of heat and moisture to be accurately observed. It also includes several cold-air outbreak flights from the ACCACIA project (flying over sea ice around Svalbard in the Arctic during March 2013), and from the PIKNMIX project (flying over the sea between Iceland and the UK). Several case studies will be chosen for closer examination and simulation. You will also have the opportunity to take part in a major international field campaign focused on the Iceland and Greenland Seas in March 2018, when new aircraft-based and ship-based boundary-layer observations of cold-air outbreaks will be made. The Iceland Sea is relatively little-studied, but this is now changing, as we are discovering it plays a critical role in creating and transporting dense water from the subpolar seas into the North Atlantic and this role is now being affected by Arctic sea-ice retreat (Moore et al., Nat. Clim. Change, 2015; and see https://theconversation.com/declining-winter-sea-ice-near-greenland-spells-cooler-climate-for-europe-42976). This field campaign will enable a considerable step forward in our understanding of these processes, and your contribution will contribute to furthering our understanding of the role that cold-air outbreaks play in this critical region.