Microphysics and Optics in Trade Wind Cumulus Clouds

这项研究将是将于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的海洋积云中的雨(RICO)实验的一部分。这名研究人员将主要负责两个机载仪器，一个是测量云中液态水含量的粒子体积监测器(PVM)，另一个是测量云滴数量表面积的新型积分浊度计。对降水形成和拓宽云滴尺寸分布的机理的RICO研究将受益于对液态水含量的准确测量，而积分浊度计将为其他测量云滴尺寸分布的仪器提供基准。由于PVM可以以非常高的速率(高达1000赫兹)测量液态水含量，它的测量将提供一个重要的机会，以确定环境空气的夹带对云团的稀释程度，这一过程对降雨形成有重要影响。RICO的这项研究和其他研究预计将有助于更好地理解未达到冰冻水平的云中降雨的形成方式，并更好地描述发生在浅层信风云中的降水和其他过程。由于这样的云覆盖了地球的大片区域，现在人们对它们的了解很少，这项研究与RICO的其他研究一起，有可能在气候模型中更好地表示降水和辐射传输。

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.