Slant-Path Sensing with Ground-Based Global Positioning System (GPS) for Atmospheric Research and Climate Monitoring

了解水汽的四维分布对于大气的诊断和预报是至关重要的。 在过去几年中，人们发现，除其他变量外，大气湿度以可预测的方式影响全球定位系统信号的传播。 目前，GPS卫星发射的微波信号遍布大气层。 由大气中的水分在这些信号中引起的折射延迟可以被常规地测量并转换成被称为可降水量（PW）的垂直积分量的精确测量。 在先前的支持下，主要研究者建立了一个基于大学的GPS系统，称为SuomiNet，以测量PW并通过互联网将此信息提供给感兴趣的用户，用于研究和教育。 根据目前的奖项，将增加对SuomiNet的强大增强。 主要研究人员将开发和验证技术，以确定从卫星到地面接收器的全球定位系统信号的倾斜延迟。 倾斜延迟可用于改进高分辨率三维水汽和风分析，这是改进中尺度建模和预报的重要一步。 工作包括倾斜延迟GPS计算方法的发展和同化的倾斜延迟数值天气模式。 如果成功的话，开发的技术将大大提高大气变量的分辨率，可用于推进短期预报。 SuomiNet接收器将继续主要设在大学，并将为大气测量方面的地方教育工作作出贡献。

Knowledge of the four dimensional distribution of water vapor is crucial for diagnosis and prediction of the atmosphere. Over the last several years it was discovered that, among other variables, atmospheric moisture affects the propagation of Global Positioning System (GPS) signals in a predictable manner. Currently, microwave signals transmitted by GPS satellites pervade the atmosphere. Refractive delays induced in these signals by the moisture in the atmosphere can be routinely measured and converted into accurate measurements of a vertically integrated quantity known as precipitable water (PW). Under prior support, the Principal Investigators established a university-based GPS system, known as SuomiNet, to measure PW and provide this information to interested users over the Internet for research and education. Under the current award, a powerful augmentation to SuomiNet will be added. The Principal Investigators will develop and validate techniques to determine the slant delay of GPS signals from the satellite to the ground-based receivers. Slant delays can be used to improve high-resolution, three-dimensional water vapor and wind analyses, which is an important step in improving mesoscale modeling and forecasting. The work includes development of slant delay GPS computational methods and assimilation of slant delays into numerical weather models. If successful, the developed techniques will provide much improved resolution of atmospheric variables, which can be used to advance short term forecasting. The SuomiNet receivers will continue to be based primarily at universities and will contribute to local educational efforts in atmospheric measurements.