SGER: New Approaches for the Measurement of Microphysics in Extratropical Hurricanes

这是一笔用于探索性研究的小额赠款，用于支持Garrett博士参加2003年秋季的飓风温带过渡实验（ETHEX）。ETHEX的目标是观察大西洋飓风从热带向北移动并演变成中纬度气旋的特征。这类风暴通常规模大、强度大，可能造成暴雨、洪水、财产损失和生命损失。作为ETHEX的一部分，由加拿大国家研究委员会和加拿大气象局联合操作的Convair 580研究飞机将进行风暴穿透飞行，以测量起源于飓风的中纬度风暴的微物理特性。测量包括水滴的大小分布，每单位体积的云水和冰的数量，以及冰晶的大小和形状。加勒特博士将在飞机上安装一个云积分浊度计（CIN），这是一种由格伯科学公司制造的仪器，用于测量云的某些体积积分光学特性，特别是消光系数和不对称参数，这是衡量前向散射与总散射的重要性的指标。这个参数对于冰云和水云有不同的值。通过不对称参数，CIN提供了混合相云中冰的比例的直接测量，从而有助于实现ETHEX的目标。这是重要的信息，否则无法获得，既可以用来描述云的微观物理结构，也有助于解释其他仪器的测量结果，因为这些仪器并不总是能够区分水和冰。CIN提供的消光的独立测量也有助于验证其他仪器对液滴大小分布的测量。该项目的更广泛影响包括提高模拟和预报温带飓风的能力，并鼓励美国和加拿大云物理学家的合作。

This is a Small Grant for Exploratory Research to support the participation of Dr. Garrett in the Extratropical Transition of Hurricanes Experiment (ETHEX) in the fall of 2003. The objective of ETHEX is to observe the characteristics of Atlantic hurricanes as they move north from the tropics and evolve to take on the characteristics of midlatitude cyclones. Such storms are often large and intense, and can cause heavy rain, flooding, property damage, and loss of life. As part of ETHEX, the Convair 580 research aircraft operated jointly by the National Research Council of Canada and the Canadian Meteorological Service will make storm-penetration flights to measure the microphysical properties of midlatitude storms that originated as hurricanes. The measurements include drop-size distributions, the amounts of cloud water and ice per unit volume, and ice crystal sizes and shapes. Dr. Garrett will install on the airplane a Cloud Integrating Nephelometer (CIN), an instrument built by Gerber Scientific for measuring certain volume-integrated optical properties of clouds, specifically the extinction coefficient and the asymmetry parameter, a measure of the importance of forward scattering compared with the total scattering. This parameter has a different value for ice clouds than for water clouds. The CIN contributes to the objectives of ETHEX by providing, through the asymmetry parameter, a direct measure of the proportion of ice present in mixed-phase clouds. This is important information, not otherwise obtainable, both for characterizing the microphysical structure of the clouds and for helping to interpret the measurements of other instruments, which are not always able to distinguish between water and ice. The independent measurement of extinction that the CIN provides also helps to validate the measurements of drop-size distribution by the other instruments. Broader impacts of the project include improving the ability to model and forecast extratropical hurricanes and encouraging the collaboration of American and Canadian cloud physicists.