Remote Sensing and Radiative Forcing of Inhomogeneous Trade-Wind Cumuli

该项目的核心目标是将浅信风积云的大尺度辐射强迫作为云的宏观物理和微物理特性、云的空间组织和中尺度垂直运动的函数进行量化。我们将结合联合收割机的信风积云的宏观物理，微物理和辐射特性，这些特性是在2020年2月巴巴多斯东部的EUREC 4A活动期间通过高空和远程研究飞机（HALO）上的机载遥感云观测和现场辐照度测量获得的。我们将通过（i）多波长热红外（IR）成像仪和（ii）成对的向上和向下观察的半球宽带日射强度计和日射几何计来扩展HALO的仪器。这些宽带辐射计将提供太阳和地面辐照度测量，以量化飞行高度的大气辐射收支。红外热成像仪将以高空间分辨率（5米）和高时间分辨率（20赫兹）绘制不同红外热光谱波段的云顶亮度温度图。尚未在HALO上操作器械。因此，拟议工作计划的一个关键部分是对新仪器进行广泛的测试和校准，并开发处理和后处理数据的工具，红外热成像仪将用于开发基于红外的云产品，提供云顶温度、云液态水路径和云有效液滴大小的地图。将对这些地图进行统计分析，以获得云的分数、聚类程度和云的大小分布。这些数据将与大气参数（温度/湿度分布图、背景气溶胶、大尺度差异）相关联。宽带辐射计的观测结果将结合红外热成像仪得出的云特性图进行分析。对不同云量、云簇度和云顶温度的信风积云场景的云辐射强迫进行量化，将表明云辐射强迫对信风积云的宏观性质和组织有多敏感。参数化这种敏感性提供了一种工具，以评估贸易风积云的数值天气预报模式和全球气候模式的代表性。

The core objective of the project is to quantify the large-scale radiative forcing of shallow trade-wind cumuli as a function of the cloud macrophysical and microphysical properties, the cloud spatial organization, and the mesoscale vertical motion. We will combine macrophysical, microphysical, and radiative properties of trade-wind cumuli obtained from airborne remote sensing cloud observations and in situ irradiance measurements aboard the High Altitude and Long Range Research Aircraft (HALO) during the ElUcidating the Role of Cloud-Circulation Coupling in ClimAte (EUREC4A) campaign east of Barbados in February 2020.To retrieve the relevant cloud and radiation data, we will extend the instrumentation of HALO by (i) a multi-wavelength thermal infrared (IR) imager, and (ii) pairs of upward and downward looking, hemispheric broadband pyranometers and pyrgeometers. These broadband radiometers will provide solar and terrestrial irradiance measurements to quantify the atmospheric radiation budget at flight level. The thermal IR imager will map the cloud top brightness temperatures at different thermal IR spectral bands with high spatial (5 m) and temporal (20 Hz) resolution. The instruments were not operated on HALO yet. Therefore, a crucial part of the proposed work plan is related to extensive tests and calibrations of the new instruments and developing tools for handling and post processing the data.The thermal IR imager will be used to develop an IR-based cloud product, providing maps of cloud top temperature, cloud liquid water path and cloud effective droplet size. The maps will be analysed statistically to obtain the cloud fraction, degree of clustering, and cloud size distributions. The data will be correlated with atmospheric parameters (temperature/humidity profiles, background aerosol, large-scale divergences). The observations of the broadband radiometers will be analysed in combination with the maps of cloud properties derived from the thermal IR imager. Quantifying the cloud radiative forcing for scenes of trade-wind cumuli with different cloud fraction, degree of clustering, and cloud top temperatures will indicate how sensitive the cloud radiative forcing is with respect to the macroscopic properties and organization of trade-wind cumuli. Parameterizing this sensitivity provides a tool to evaluate the representation of trade-wind cumuli in numerical weather prediction models and global climate models.