Studies of Stratocumulus and Fair-Weather Cumulus Clouds Using a 94 GHz Droppler Cloud Radar

许多气候和预报模式不能很好地解释浅边界层云。这种缺陷的结果是气候和长期天气预测的不确定性。为了为改进云参数化和增加对关键云过程的了解提供观测基础，将使用94 GHz多普勒雷达与其他遥感系统和现场飞机观测一起研究大陆层积云和晴朗天气积云。这项研究将侧重于影响云寿命的过程，以及作为降水形成前兆的大雨滴的产生。这项工作的一个关键、独特的特点是在直升机上部署了94千兆赫雷达，使研究人员能够研究积云的整个生命周期。大陆层研究将使用广泛的数据集（超过250小时的云观测），这些数据集来自云雷达、微波辐射计、ceilometer和支持气象观测，这些观测是在美国国家科学基金会之前的支持下在宾夕法尼亚州中部收集的。这将包括对大涡结构、夹带过程以及大液滴和毛毛雨的产生的研究。将使用迈阿密大学最近开发和建造的单碟94千兆赫雷达对浅层积云进行广泛的观测。一个测云仪、一个微脉冲激光雷达、一个微波辐射计、一个红外辐射计和一个摄像机将用于支持南佛罗里达海岸线和内陆地区雷达操作的云结构测量。云形成的环境将使用雷达探空仪和915兆赫风廓线仪进行表征。此外，在一些观测期间，红外干涉仪将用于检索边界层温度和湿度剖面。直升机上的雷达将用于在风切变、稳定性和气溶胶条件变化的整个生命周期中对云的动力学和微物理进行采样。这种方法尚未被尝试过，但在改善对晴天积云中大雨滴浓度的空间分布和演化的描述以及确定小积云的寿命是否在毛毛雨产生时减少方面具有很大的潜力。P:\Pmet\ Pmet awards, f7 & &; abst\Albrecht.abs

Abstract/Albrecht Many climate and forecast models are not able to account for shallow boundary layer clouds properly. The result of this deficiency is uncertainty in climate and long-range weather predictions. To provide an observational basis for improvement of cloud parameterizations and to increase understanding of key cloud processes, a 94 GHz Doppler radar will be used with other remote sensing systems and in situ aircraft observations to study continental stratocumulus and fair-weather cumulus clouds. This study will focus on processes that affect cloud lifetime and the production of large drops that serve as precursors to the formation of precipitation. A key, unique feature of this work is the deployment of the 94 GHz radar on a helicopter to enable researchers to study the entire life cycle of cumulus clouds. The continental stratus studies will use an extensive data set (more than 250 hours of cloud observations) from the cloud radar, a microwave radiometer, a ceilometer, and supporting meteorological observations that were collected over central Pennsylvania under prior NSF support. This will include investigations of large-eddy structures, entrainment processes, and the production of large drops and drizzle. An extensive set of observations of shallow cumuli will be made using a single-dish 94 GHz radar that has recendy been developed and constructed at the University of Miami. A ceilometer, a micropulse lidar, a microwave radiometer, an IR radiometer, and a video camera will be used to support the cloud structure measurements from radar operations at shoreline and inland sites in south Florida. The environment in which the clouds form will be characterized using rawinsondes and a 915 MHz wind profiler. In addition, an infrared interferometer will be available during some observing periods for the retrieval of boundary layer temperature and moisture profiles. The radar on a helicopter will be used to sample the dynamics and microphysics of clouds over their en tire life cycles as wind shear, stability, and aerosol conditions vary. This has not been tried and has great potential to improve the description of the spatial distribution and evolution of large-drop concentrations in fair-weather cumulus clouds and to determine whether the lifetime of small cumuli decreases when drizzle is produced. P:\Pmet\pmet awds, f7 & abst\Albrecht.abs