Cirrus Coupled Cloud-Radiation Experiment: CIRCCREX

气候和天气预报模型要求了解对流层(海拔6-14公里)高空的卷云如何影响我们的气候。卷云覆盖了全球高达30%的区域，其影响应该准确地包含在全球气候模型中。云有两个主要影响：它们是水文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(使地球表面降温)，又捕获从表面发射的热能(因为它们很冷，向太空发射的能量比同等晴朗的天空要少)。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。晶体可以呈现无数的形状，存在于特定云中的形状取决于条件和粒子经历的进化序列；随着时间的推移，生长、聚集和/或消散取决于它们经历的温度、湿度和气象环境的变化。不同的晶体大小和形状以不同的方式反射和散射光。一些晶体形状在反射阳光方面很有效，但不能反射热辐射，有些晶体形状则相反。云对辐射收支的净影响取决于其内部晶体的微观形状。通过测量云层发出的热量及其内部晶体性质(“微物理”)，我们可以确定两者之间的联系，从而确定云层对气候的整体影响。CIRRUS模型已被推导出来，用于计算光谱中不同晶体类型的预期响应，这些模型通常与使用云探测器的现场飞行活动测量中发现的预测的颗粒大小和形状(颗粒大小分布，PSD)相结合。它们是参数化的(简化的)，并用于气候模型和大气环流模型(GCM)，例如。在数值天气预报(NWP)和气候变化方面，这些卷云模型还没有得到全光谱的检验。已经对一些晶体类型在短波中的特殊辐射性质以及其他类型的晶体在部分长波中的特定辐射性质进行了一些研究，但还没有一种成功的测量方法来同时测量云中晶体大小和类型的精确组成的全光谱。我们计划开展一项新颖的飞行活动，将从长波到短波的全光谱辐射测量(125-0.3微米)与最先进的晶体PSD、冰水含量和温度等测量相结合。我们将测试大气模型中用于描述卷云的散射模型和PSD参数化，例如英国气象局(MO)统一模型数值天气预报(NWP)，并由MO项目合作伙伴实施模型改进。我们的项目之所以有可能，是因为NERC资助的研究导致：先进的云探测仪器和软件工具，解决了入口处冰晶破碎的问题和过去冰晶尺寸分布的巨大不确定性；以及在帝国理工学院(IC)开发了独特的远红外仪器Tafts。能够从飞机上测量整个光谱，从而同时测量卷云晶体的类型、大小、温度和IWC、粗糙度等，这是一种仅在英国FAAM飞机上提供的独特设施。我们将IC的远红外辐射测量、中红外至太阳辐射测量、曼彻斯特大学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式和NWP中卷云影响的模型和参数。

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.