Impact of Total Column Water Vapor Measurements on Short- to Medium- Range Forecasts of North American Monsoon Precipitation

本研究的目的是评估从地面全球定位系统（GPS）接收器观测到的总柱可降水量（TPW）的能力，以改进作为北美季风（NAM）一部分的降水预报。不结盟运动于5月在墨西哥南部开始，沿着西马德雷山脉向北和西扩展，在7月底和8月初到达美国西南部。大部分不正运动降水来自中尺度气象过程，包括飑线和中尺度对流复合体，因此成功的数值天气预报需要使用高分辨率的非流体静力天气预报模式。此外，以前的工作表明，对不结盟运动降水的成功预测必须包括对流起始区域的观测，并充分代表进入不结盟运动区域的低层水汽涌动。因此，本项目考察了先进研究天气研究和预报模式（WRF ARW）的能力，该模式综合了非流体静力学高分辨率内域，利用来自美国（Suominet）和墨西哥（TLALOC-Net，一个目前正在建设的100个站点网络）的GPS地面站网络的连续TPW观测，产生熟练的不正非降水预报。进一步的实验结合了加勒比地区更遥远的椰子网的观测结果。由于大气水蒸气的存在，GPS信号从发射卫星传播到地面接收器的延迟导致GPS接收器检测到TPW。除了这些固定网络之外，pi还将与墨西哥国立自治大学的同事合作，在2013年不结盟运动季节在墨西哥北部（对流启动区域）部署10台GPS接收器。除了其科学价值外，由于不干流的重要性，这项工作具有更广泛的社会影响，不干流约占墨西哥西北部和美国西南部年降水量的50-70%。不结盟运动在温暖季节影响供水和需求、恶劣天气、极端高温、干旱和野火。此外，这项工作将促进美国和墨西哥科学家在两国都感兴趣的研究领域的合作，而且这项工作将支持和培训一名研究生。

The objective of this research is to evaluate the ability of observations of total column precipitable water (TPW) from ground-based Global Positioning System (GPS) receivers to improve forecasts of precipitation occurring as part of the North American Monsoon (NAM). The NAM begins in southern Mexico in May and expands north and westward along the Sierra Madre Occidental, reaching the US Southwest in late July and early August. The bulk of NAM precipitation comes from mesoscale meteorological processes, including squall lines and mesoscale convective complexes, and thus successful numerical weather prediction requires the use of a high-resolution nonhydrostatic weather forecasting model. In addition, previous work suggests that successful prediction of NAM precipitation must include observations from the regions of convective initiation, and adequately represent low-level surges of moisture into the NAM region. Thus, this project examines the ability of the Advanced Research Weather Research and Forecasting model (WRF ARW), integrated using a nonhydrostatic high resolution inner domain, to produce skillful NAM precipitation forecasts using continuous TPW observations from a network of GPS ground stations in the US (Suominet) and in Mexico (TLALOC-Net, a 100-station network currently under construction), with further experiments incorporating observations from the more distant COCONet network in the Caribbean. GPS receivers detect TPW as a consequence of the delay in GPS signal propagation from the transmitter satellite to the ground-based receiver due to the presence of atmospheric water vapor. In addition to these fixed networks, the PIs will work with colleagues at the National Autonomous University of Mexico on a field campaign in which 10 GPS receivers will be deployed in Northern Mexico (in the region of convective initiation) over the 2013 NAM season.In addition to its scientific merit, the work has broader societal impacts due to the importance of the NAM, which accounts for approximately 50-70% of the annual precipitation in northwest Mexico and the Southwest US. The NAM impacts water supply and demand, severe weather, extreme heat, drought and wildfire during the warm season. In addition, the work will foster collaborations between US and Mexican scientists in a research area of interest to both countries, and the work will support and train a graduate student.