GRACES (G-band RAdar for Cloud and prEcipitation Studies)

GRACES（用于云和降水研究的 G 波段雷达）

• 批准号: NE/V001183/1
• 负责人: Alessandro Battaglia
• 金额: $ 70.72万
• 依托单位: University of Leicester
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2021
• 资助国家: 英国
• 起止时间: 2021 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FV001183%2F1
• 关键词: GRACES; band; RAdar; Cloud; prEcipitation

Despite the well-recognised influence of clouds and precipitation on our climate, there are still critical gaps in our ability to observe cloud properties that are needed to test and improve how cloud processes are represented in models. This leads to clouds and aerosols being the biggest source of uncertainty in climate models, according to the IPCC. In addition, uncertainties about cloud processes have important impacts on our ability to predict the weather, because precipitation is produced by clouds, clouds modulate the amount of sunlight we receive during the day and heat we lose at night, and latent heat processes in clouds and precipitation drive dynamical changes in storms. Low-altitude clouds of liquid water droplets cover large swathes of the globe, and cool the earth's climate. However our ability to simulate these clouds in climate models is poor, and the production of drizzle has been identified as a key weakness. We need new observations to unravel the processes in these clouds and improve their representation in simulations. Meanwhile ice clouds cover around one third of the earth at any one time, and provide a net warming on average. However the magnitude of this warming is very uncertain, and their impact on our climate is very sensitive to what we assume about their physics. Thus we urgently need to constrain those physical processes controlling how ice particles evolve in natural clouds. Finally, stratiform precipitation is an important component of the hydrological cycle and the radiation budget. Typically such precipitation include an ice phase aloft and a liquid phase at lower altitude. Yet there are processes in both phases which remain uncertain, and require new observations to robustly constrain them.Our novel proposal exploits new radar technology to break through the current limitations on the information we can currently retrieve about cloud properties and the processes that drive the evolution of the hydrometeors within them. With the help of our project partners at the Met Office and the ECMWF we will use this information to improve the simulation of cloud processes in weather and climate forecasts. In 2018 the UK Space Agency and Centre for Earth Observation Instrumentation agreed to fund the development of a new 200 GHz (G-band) Doppler radar system, called GRaCE, led by investigators Huggard and Battaglia. This ground-breaking demonstrator instrument will collect its first data at the Chilbolton Observatory early in 2020, and will be able to penetrate multiple layers of clouds with unprecedented sensitivity to small sub-millimetre particle thanks to the radar 1.5 mm wavelength, the smallest for any cloud radar system worldwide. The radar will be operated for 22 months in synergy with a suite of other remote sensing instruments. The unprecedented dataset will be exploited by GRACES scientists who are leaders in radar remote sensing techniques and have spearheaded retrieval techniques for multi-wavelength Doppler radars. Vertical profiles of cloud physical properties including water content as well as drizzle drop and ice crystal size distributions will be obtained and this data will be used to test the representation of cloud processes in numerical models in much greater detail than has been possible before.Through this leap forward in our ability to observe clouds the GRACES system will become the forerunner for future development of a new stream of ground-based remote sensing instruments, greatly strengthening the current Earth observing system. The high frequency of the radar means that it will also be suitable for development into air-borne/space-borne instruments for cloud related studies, and indeed the proposal is very timely given parallel efforts at NASA's JPL to build an airborne differential absorption radar (for measuring water vapour) at smaller frequencies (165 to 173 GHz), and to develop CubeSat radars in the G-band (see NASA-JPL's LoS).

尽管云和降水对我们的气候的影响是众所周知的，但在我们观察云特性的能力方面仍然存在严重的差距，这是测试和改进云过程在模型中的表现所必需的。根据政府间气候变化专门委员会的说法，这导致云层和气溶胶成为气候模型中最大的不确定性来源。此外，云过程的不确定性对我们预测天气的能力有重要影响，因为降水是由云产生的，云调节我们在白天获得的阳光和我们在夜间损失的热量，云中的潜热过程和降水推动风暴的动态变化。低海拔的液态水滴云层覆盖了地球的大片地区，使地球气候降温。然而，我们在气候模型中模拟这些云的能力很差，而毛毛雨的产生被认为是一个关键的弱点。我们需要新的观测来解开这些云中的过程，并改进它们在模拟中的表现。与此同时，冰云在任何时候都覆盖了大约三分之一的地球，并提供了平均净变暖。然而，这种变暖的幅度非常不确定，它们对我们气候的影响非常敏感，取决于我们对它们的物理假设。因此，我们迫切需要限制那些控制自然云中冰粒如何演化的物理过程。最后，层状降水是水文循环和辐射收支的重要组成部分。通常，这样的降水包括高空的冰相和较低海拔的液态。然而，在这两个阶段都有一些过程仍然不确定，需要新的观测来有力地约束它们。我们的新提议利用新的雷达技术来突破目前我们可以检索到的关于云特性和驱动其中水流星演化的过程的信息的限制。在气象局和欧洲气象中心的项目合作伙伴的帮助下，我们将利用这些信息改进天气和气候预报中的云过程模拟。2018年，英国航天局和地球观测仪器中心同意资助开发一种新的200 GHz(G波段)多普勒雷达系统，名为Grace，由调查人员Huggard和Battaglia领导。这一突破性的演示仪器将于2020年初在奇尔博顿天文台收集第一批数据，并将能够穿透多层云层，对微小的亚毫米粒子具有前所未有的灵敏度，这要归功于雷达1.5毫米波长，这是世界上任何云雷达系统中最小的。该雷达将与其他一套遥感仪器协同工作22个月。这一史无前例的数据集将被GRACES科学家利用，他们是雷达遥感技术的领导者，并率先采用了多波长多普勒雷达的检索技术。将获得云物理性质的垂直剖面，包括水分以及毛毛雨和冰晶尺寸分布，这些数据将被用来比以前更详细地测试云过程在数值模式中的表示。通过我们观察云能力的这一飞跃，GRACE系统将成为未来开发新的陆基遥感仪器的先驱，大大加强目前的地球观测系统。该雷达的高频率意味着它也将适合发展成为与云有关的研究的空中/空间仪器，事实上，这项提议非常及时，因为美国宇航局喷气推进实验室正在同时努力在较低频率(165至173 GHz)建立一个空中差分吸收雷达(用于测量水蒸气)，并开发G波段的立方体卫星雷达(见美国航天局喷气推进实验室的LOS)。

项目成果

Advantages of G-band radar in multi-frequency, liquid phase microphysical retrievals

G波段雷达在多频液相微物理反演中的优势

• DOI: 10.5194/egusphere-2024-205
• 发表时间: 2024
• 作者: Courtier B

First Observations of G-Band Radar Doppler Spectra

G 波段雷达多普勒频谱的首次观测

• DOI: 10.1029/2021gl096475
• 发表时间: 2022
• 期刊: Geophysical Research Letters
• 影响因子: 5.2
• 作者: Courtier B