Cirrus Coupled Cloud-Radiation Experiment: CIRCCREX

气候和天气预测模型需要了解对流层高处（海拔6-14公里）的卷云如何影响我们的气候。卷云覆盖了全球30%的面积，它的影响应该准确地包括在全球气候模型中。云有两个主要影响；它们是水循环中的主要大气成分，但它们也捕获辐射，既将阳光反射回太空（冷却地球表面），又捕获从表面发射的热能（因为它们是冷的，向太空发射的能量比同等无云的天空少）。短波（阳光）和长波（热辐射）效应之间的平衡取决于云层的高度和厚度，以及构成云层的冰晶的大小和形状等因素。晶体可以呈现无数种形状，而存在于特定云层中的形状取决于条件和粒子经历的进化顺序；随着时间的推移，随着温度、湿度和气象环境的变化而增长、聚集和/或消散。不同大小和形状的晶体以不同的方式反射和散射光线。有些晶体形状能有效反射阳光，但不能反射热辐射，有些则相反。云对辐射收支的净影响取决于云内晶体的微观形状。通过测量云层散发的热量及其内部晶体性质（“微物理学”），我们可以确定两者之间的联系，从而确定云层对气候的总体影响。已经建立的卷云模型可以计算不同晶体类型在整个光谱中的预期响应，这些模型通常与使用云探测器在飞行活动现场测量中发现的预测粒度和形状（粒度分布，PSD）相结合。这些参数化（简化）并用于气候模式和一般环流模式（GCMs），例如。在数值天气预报（NWP）和气候变化中，但这些卷云模式尚未在全谱范围内进行测试。对某些晶体类型在短波中的特定辐射特性和其他晶体类型在部分长波中的特定辐射特性进行了一些研究，但尚未成功地测量覆盖全光谱同时测量云中晶体尺寸和类型的精确组成。我们计划进行一项新的飞行活动，结合从长波到短波的全光谱辐射测量（125-0.3微米），以及最先进的晶体psd，冰水含量和温度等测量。我们将测试用于描述大气模式中的卷云的散射模型和PSD参数化，例如英国气象局（MO）统一模式数值天气预报（NWP），我们的MO项目合作伙伴实施了模型改进。我们的项目之所以成为可能，是因为NERC资助的研究导致了：最先进的云探测仪器和软件工具，解决了冰晶在入口孔破碎的问题，以及过去冰晶尺寸分布的巨大不确定性；以及帝国理工学院（IC）独特的远红外仪器TAFTS的开发。从飞机上测量整个光谱的能力，因此同时测量卷云晶体类型，尺寸，温度和IWC，粗糙度等，是英国FAAM飞机上唯一可用的独特设施。我们将IC的远红外辐射测量，MO的中红外辐射测量，曼彻斯特和赫特福德郡大学的云微物理仪器和专业知识，以及UKMO/FAAM与互补的云和大气状态测量相结合。这将给卷云建模带来飞跃，我们的数据集允许测试和开发用于预测气候模型和NWP中卷云影响的模型和参数化。

Climate and weather prediction models demand understanding of how cirrus clouds, high in the troposphere (6-14km in altitude) affect our climate. Cirrus covers up to 30% of the globe and its effects should be accurately included in global climate models. Clouds have two main effects; they are the main atmospheric component in the hydrological cycle, but they also trap radiation, both reflecting sunlight back to space (cooling the Earth's surface) and trapping the thermal energy emitted from the surface (as they are cold, emitting less energy to space than an equivalent cloudless sky). The balance between the shortwave (sunlight) and longwave (thermal radiation) effect depends on factors such as altitude and thickness of the cloud, and the size and shape of the ice crystals that make up the cloud. The crystals can take on myriad shapes, and the shapes existing in particular clouds depend on conditions and on the evolutionary sequence that the particles experience; growing, aggregating and/or dissipating over time, dependant on the changes in temperature, humidity and meteorological environment they experience. Different crystal sizes and shapes reflect and scatter light in different ways. Some crystal shapes are efficient at reflecting sunlight, but not thermal radiation and some the other way round. The net effect of a cloud on the radiation budget depends on the microscopic shapes of the crystals inside it. By measuring both the heat emitted by the cloud and its internal crystal properties ('microphysics') we can determine the link between the two, and hence the overall effect the cloud is having on the climate. Cirrus models have been derived that calculate expected response of different crystal types across the spectrum, and these are usually combined with predicted particle size and shapes (Particle Size Distributions, PSD) found from in-situ flight campaign measurements using cloud probes. These are parameterised (simplified) and used in climate models and general circulation models (GCMs), eg. in numerical weather prediction (NWP) and climate change, but these cirrus models have not been tested across the full spectrum. Some studies have been made of specific radiative properties of some crystal types in the shortwave, and of other crystal types in parts of the longwave, but there has not been a successful measurement covering the full spectrum simultaneously measuring the precise make up of the crystal sizes and types in a cloud. We plan a novel flight campaign combining full spectrum radiative measurements (125-0.3 microns) from longwave to shortwave, with state-of-the-art measurements of crystal PSDs, the ice water content and temperature etc. We will test scattering models and PSD parameterisations used to describe cirrus cloud in atmospheric models, such as the UK MetOffice (MO) Unified model Numerical Weather Prediction (NWP) with model improvements implemented by our MO project partners. Our project is possible because of NERC funded research that led to: state-of-the-art cloud probe instruments and software tools that addressed problems of ice crystal shattering at the inlet apertures and the great uncertainty in ice crystal size distributions of the past; and the development of the unique far-IR instrument TAFTS at Imperial College (IC). The ability to measure the entire spectrum from an aircraft, and so simultaneously measure the cirrus crystal types, sizes, temperature and IWC, roughness etc., is a unique facility only available on the UK FAAM aircraft. We combine radiometry in the far-IR of IC, in mid-IR to solar of MO, cloud microphysics instrumentation and expertise of Manchester and Hertfordshire Universities, and UKMO/FAAM with complementary cloud and atmospheric state measurements. This will give a leap forward to cirrus modelling, our datasets allowing testing and development of models and parameterizations used to predict the effect of cirrus in climate models and NWP.