Cloud Halos and their Roles in the Atmospheric Radiation Balance and Climate

最近的观测表明，围绕着不断增长的积云的空气有时几乎充满了水蒸气。 计算表明，云周围的这些水汽晕或“晕”可以解释太阳辐射吸收的显著增加。 该项目的目的是以高精度和高分辨率测量积云周围的蒸气场，并利用这些信息计算辐射传输和评估云-环境相互作用对云微物理学的影响。 具体目标如下：-测量对流云内和周围的水汽场，并具有足够的细节，以表征相对于云边缘的三维水汽结构;-同时测量云晕内气溶胶的尺寸分布、成分和光学性质;-分析所得测量结果，以便提供几个完整的记录案例，用于辐射传输计算;- 进行辐射转移分析，包括对观测到的水蒸气、气溶胶和云的分布进行吸收和加热率计算;- 确定辐射分析对气候模拟的影响。测量将使用CIRPAS Twin Otter飞机进行，配备了由Aerodyne Research沿着开发的称为快速水汽监测器的新仪器，以及用于测量气溶胶、云凝结核、云滴和液态水含量的仪器。 不同复杂程度的计算机代码将用于辐射传输计算。 结果涉及异常云吸收的问题，这是指已经观察到的云的太阳吸收和使用米氏散射理论计算的吸收适用于云滴人口之间的差异。 这是Cal Tech和Aerodyne Research，Inc.之间的合作研究项目。 该合作的Aerodyne组件由ATM-9910744，John T。杰恩，派。

Recent observations indicate that the air surrounding growing cumulus clouds is sometimes nearly saturated with water vapor. Calculations show that these vapor shrouds or "halos" around clouds can account for a significant increase in the absorption of solar radiation. The purpose of this project is to measure the vapor field around cumulus clouds with high accuracy and resolution and to use the information in calculations of radiative transfer and in assessing the consequences of cloud-environment interactions on cloud microphysics. The specific objectives are as follows:- To measure the vapor field in and around convective clouds with sufficient detail to characterize the 3-dimensional vapor structure relative to cloud edges;- To measure concurrently the size distribution, composition, and optical properties of aerosols within the cloud halo;- To analyze the resulting measurements in order to provide several completely documented cases for use in radiative transfer calculations;- To carry out radiative transfer analyses including absorption and heating rate calculations for the observed distributions of water vapor, aerosols, and cloud;- To determine the implications of the radiation analysis for climate modeling.The measurements will be conducted with the CIRPAS Twin Otter aircraft, equipped with a new instrument called the Fast Water Vapor Monitor developed by Aerodyne Research along with instruments for measuring aerosols, CCN, cloud droplets, and liquid water content. Computer codes with different degrees of complexity will be used for the radiative transfer calculations. The results bear on the question of anomalous cloud absorption, which refers to the discrepancies that have been observed between the observed solar absorption by clouds and the absorption calculated using Mie scattering theory applied to populations of cloud drops. This is a collaborative research project between Cal Tech and Aerodyne Research, Inc. The Aerodyne component of the collaboration is supported by ATM-9910744, Dr. John T. Jayne, PI.