Measurements of the Size, Shape, Scattering Phase Function and Extinction Coefficient of Ice Crystals at South Pole Station

9909593Lawson这个项目是对南极站大气中卷云的辐射特性和冰晶的光散射特性进行为期三年的研究，使用高分辨率数字云粒成像仪自动按大小和形状对云粒进行分类。许多理论和实验研究表明，粒子的大小和形状强烈影响云粒子的辐射效应，特别是冰晶。两台云粒子成像仪将在南极运行，配合正在进行的辐射传输计划，野外工作将在2000-01年和2001-02年南半球夏季进行。颗粒图像、浓度和粒度分布将在现场处理，并将进行初步分析，以确保数据质量。该系统目前的软件功能允许剔除伪影、计算各种尺寸和形状参数、散射特性以及冰/水分数。单独的观测以及集体统计数据将大大增加几个同时进行的关于雪、大气中冰晶和地表附近温室气体排放特征的实验。这些数据，加上对云底高度、温度和湿度结构等环境条件的测量，将允许开发云和云粒特性的气候学，并开发新的算法，以显著改善在大气环流模式中对辐射过程的表示。

9909593LawsonThis project is a three-year study of the radiative characteristics of cirrus clouds and the light-scattering properties of ice crystals in the atmosphere at South Pole Station, using a high-resolution digital cloud particle imager to automatically classify cloud particles by size and shape. A number of theoretical and experimental studies have demonstrated that particle size and shape strongly affect the radiative effects of cloud particles, and specifically ice crystals.Two cloud particle imagers will be operated in Antarctica in cooperation with an ongoing radiation transfer program, with field work to be carried out in the 2000-01 and 2001-02 austral summer seasons. Particle images, concentrations, and size distributions will be processed on site and preliminary analyses will be conducted to assure data quality. Current software capabilities of the system allow the rejection of artifacts, the computation of various size and shape parameters, of scattering characteristics, and of ice/water fraction. The individual observations, as well as the collective statistics will significantly add to several concurrent experiments concerning the emission characteristics of snow, of ice crystals in the atmosphere, and of greenhouse gases near the surface. This data, together with measurements of environmental conditions such as cloud base altitude, temperature, and humidity structure, will allow the development of a climatology of cloud and cloud particle properties, and of new algorithms to substantially improve representations of radiation processes in general circulation models.***