Microphysics and Optics in Trade Wind Cumulus Clouds

这项研究将成为海洋积云降雨实验（RICO）的一部分，这是一项将于2004-2005年冬季进行的关于信风积云和暖云中降雨形成的合作研究。该研究员将主要负责两个机载仪器，一个是用于测量云中液态水含量的粒子体积监测器（PVM），另一个是用于测量云滴数量表面面积的新型积分浊度计。对降水形成和扩大云滴大小分布机制的RICO研究将受益于对液态水含量的精确测量，而积分浊度计将为测量云滴大小分布的其他仪器提供基准。由于PVM可以以非常高的速率（高达1000hz）测量液态水的含量，它的测量将提供一个重要的机会来确定云包被环境空气夹带稀释的程度，这一过程对降雨的形成有重要影响。这项研究和RICO的其他研究预计将使人们更好地了解在未达到冰点的云中雨水是如何形成的，并更好地描述在浅信风云中发生的降水和其他过程。由于这种云覆盖了地球的大片区域，目前对其了解甚少，因此，本研究与RICO的其他研究相结合，有可能在气候模式中更好地表示降水和辐射转移。

This study will be part of the Rain in Cumulus over the Ocean (RICO) experiment, a collaborative study of trade-wind Cumuli and of rain formation in warm clouds that will be conducted in the winter of 2004-2005. This investigator will have primary responsibility for two airborne instruments, a Particle Volume Monitor (PVM) to measure the liquid water content of clouds and a new integrating nephelometer that measures the surface area of the cloud droplet population. The RICO studies of precipitation formation and of mechanisms that broaden the cloud droplet size distribution will benefit from accurate measurement of the liquid water content, and the integrating nephelometer will provide a benchmark for other instruments that measure the cloud droplet size distribution. Because the PVM can measure the liquid water content at very high rate (up to 1000 Hz), its measurements will provide an important opportunity to identify the degree to which cloud parcels are diluted by entrainment of environmental air, a process that has an important effect on rain formation. This and other studies in RICO are expected to lead to a better understanding of how rain forms in clouds that do not reach the freezing level and a better characterization of precipitation and other processes that occur in shallow trade-wind clouds. Because such clouds cover large areas of the Earth and are now poorly understood, this study in association with others in RICO has the potential to lead to better representations of precipitation and radiative transfer in climate models.