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

这项研究的目的是评估从地基全球定位系统(GPS)接收器观测总柱状可降水量(TPW)的能力，以改进对北美季风(NAM)降水的预报。不结盟运动于5月在墨西哥南部开始，沿马德雷西部山脉向北和向西扩展，7月底和8月初到达美国西南部。大部分NAM降水来自中尺度气象过程，包括锋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静力天气预报模式。此外，以前的工作表明，对北冰洋降水的成功预报必须包括来自对流起始区的观测，并充分反映进入北冰洋区域的低水平水汽涌动。因此，本项目审查了高级研究天气研究和预报模式(WRF ARW)的能力，该模式使用非静力高分辨率内域进行综合，利用来自美国(Suominet)和墨西哥(Tlaloc-Net，目前正在建设中的100个站网络)的GPS地面站网络(Tlaloc-Net，目前正在建设中的一个100个站网络)的连续TPW观测，制作巧妙的不结盟运动降水预报，并进行了进一步的实验，纳入了加勒比地区更远的CoNet网络的观测。由于大气水蒸气的存在，GPS信号从发射机卫星传播到地面接收器的延迟，GPS接收器检测到TPW。除了这些固定的网络，PIS还将与墨西哥国立自治大学的同事合作开展一项实地活动，在2013年不结盟运动季节期间，将在墨西哥北部(对流起始地区)部署10台GPS接收器。除了科学价值外，这项工作还具有更广泛的社会影响，因为不结盟运动的重要性，它约占墨西哥西北部和美国西南部年降水量的50%-70%。在温暖的季节，不结盟运动会影响水的供需、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感兴趣的研究领域的合作，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.