Collaborative Research: Spatial Averaging of Oceanic Rainfall Variability using Underwater Sound

摘要：降雨固有的时空变异性使降雨成为任何地方最难以测量的地球物理量之一，但它也是最重要的地球物理量之一。声波雨量计（ARGs）通过聆听雨水撞击海洋表面产生的水声信号来探测和测量降雨量，可以在海洋区域提供这些数据。然而，声雨量测量的几个特点尚未得到充分的探讨。这包括降雨信号随部署深度的固有空间平均，测量海洋环境中雨滴大小分布的能力，以及测量的高时间分辨率。我们建议通过在深水（2公里）系泊上部署几个垂直分离的arg，但在高分辨率x波段偏振（X-POL）沿海气象雷达（小于40公里）的范围内，研究与arg相关的固有空间平均。一个密集的（~20计）雨量计网络也将安装在雷达40公里范围内，以提供雷达数据的比较验证。将在近距离（约5公里）安装一个二维视频分差仪，用于X-POL测量的偏振算法开发和评估。X-POL雨量估计将用于验证水滴大小分布的声学测量结果和随后的降雨类型分类。水听器上降雨的空间分布将用于预测作为深度函数的接收声信号。拟议的实地试验将首次允许用高分辨率雷达对水声降雨测量进行全面调查，从而允许检查深水（公海和海洋）声学测量对遥感（雷达和卫星）降雨估计的验证潜力。验证海洋降雨测量值是气候研究和气候变化及其对人类社会的后续影响的可预测性的重要组成部分。这将是三所大学和雅典国家天文台（希腊）之间的合作努力，从而建立全球科学和工程基础设施。人力资源开发将包括学生参与实地测量和相关研究。

ABSTRACTPI/Institution: Nystuen / UW Proposal No: OCE-0241245PI/Institution: Anagnostou / UConn Proposal No: OCE-0241552PI/Institution: Amitai / UMBC Proposal No: OCE-0241186The inherent spatial and temporal variability of rainfall makes rain one of the most difficult geophysical quantities to measure anywhere, and yet it is one of the most important. Acoustic rain gauges (ARGs), which detect and measure rainfall rate by listening for the underwater sound signal generated by rain striking the ocean surface, can provide these data in oceanic regions. However, there are several features of the acoustic rainfall measurement that have not been fully explored. These include the inherent spatial averaging of the rainfall signal with depth of deployment, the ability to measure drop size distribution in the oceanic environment, and the high temporal resolution of the measurement. We propose to examine the inherent spatial averaging associated with ARGs by deploying several vertically separated ARGs on a mooring placed in deep water (2 km), but within range of a high-resolution X-band polarimetric (X-POL) coastal weather radar (less than 40 km). A dense (~20 gauges) rain gauge network will also be installed within a 40 km range of the radar to provide a comparison validation of the radar data. A two-dimensional video disdrometer will be installed at closer range (~5 km) to be used for polarimetric algorithm development and evaluation of the X-POL measurements. The X-POL rain estimates will be used to validate the acoustic measurement of drop size distribution and the subsequent classification of rainfall type. The spatial distribution of rainfall over the hydrophones will be used to predict the received acoustic signal as a function of depth. The proposed field experiment will permit for the first time a comprehensive investigation of underwater acoustic rainfall measurements with a high-resolution radar, thus allowing an examination of the deep-water (open sea and oceans) validation potential of acoustic measurements for remote sensing (radar and satellite) rainfall estimates. Validation of oceanic rainfall measurements is an important component of climate research and the predictability of climate change with its subsequent impact on human societies. This will be a collaborative effort between 3 universities and the National Observatory of Athens (Greece), thus building global science and engineering infrastructure. Human resource development will include student participation in both field measurements and associated research.