SGER: Observing the Interdependence of Precipitation and Precipitable Water Vapor during the North American Monsoon Experiment (NAME)

本研究的总体科学目标是了解北美季风（NAM）期间墨西哥西北部西马德雷山脉（Sierra Madre Occidental， SMO）夏季降水与垂直综合可降水量（PWV）的相互关系。重点是在几个时间尺度上描述和理解SMO内的PWV、边界层湿度、风、对流风暴环境、降水和蒸发，以及它们如何受到大尺度天气特征（如倒槽、热带风暴和海湾浪）的调制，以及它们如何受到前一天对流活动的影响。PI假设在NAME区域内存在一个强大的PWV日循环，导致SMO分水岭以西的中海拔、SMO山麓和墨西哥刺林区出现最大对流有效势能（CAPE）和最小对流抑制（CIN），与观测到的夏季最大降雨量和对流风暴强度区域一致。进一步假设，夏季频繁影响NAME地区的瞬态中尺度和大尺度天气特征（如有组织的大中尺度对流系统（MCSs）、加利福尼亚湾向北的低空水汽浪涌、向西移动的中高层气旋和倒槽以及向北移动的热带扰动）显著调节了PWV的日循环。为了实现他的目标，PI将在SMO的各个地点放置一个由6个GPS接收器（提供PWV的连续测量）和地面气象仪器组成的网络，以便在NAME野外活动（2004年夏季）期间进行观测。更广泛的影响包括提高对北美季风区夏季降雨调节过程的理解，这可能导致更准确的降水预报，有利于包括水管理在内的社会活动。

The overall scientific objective of this investigation is to understand the interdependence of the summertime precipitation and vertically integrated precipitable water vapor (PWV) in the Sierra Madre Occidental (SMO) Mountains in Northwestern Mexico during the North American Monsoon (NAM). The focus is on characterizing and understanding, at several time scales, the PWV, boundary layer moisture, winds, convective storm environment and precipitation and evaporation within the SMO and how they are modulated by larger-scale weather features, such as inverted troughs, tropical storms, and Gulf surges as well as how they are affected by the previous day's convective activity. The PI hypothesizes that a strong diurnal cycle in PWV exists within the NAME region that leads to maximum convective available potential energy (CAPE) and minimum convective inhibition (CIN) over the middle elevations, SMO foothills and the Mexican thorn forest region, west of the divide of the SMO, coinciding with the area of observed maximum summer rainfalls and convective storm intensities. It is further hypothesized that this diurnal cycle of PWV is modulated significantly by transient mesoscale and large-scale weather features that frequently affect the NAME region during summer, e.g., organized and large mesoscale convective systems (MCSs), northward surges of low-level moisture up the Gulf of California, westward moving middle and upper-level cyclones and inverted troughs, and northward moving tropical disturbances. To accomplish his goals, the PI will place a network of 6 GPS receivers (that provide continuous measurements of PWV) and surface meteorological instrumentation at locations across the SMO to make observations during the NAME field campaign (summer 2004). Broader impacts include improved understanding of the processes that regulate summer rainfall over the North American monsoon region, which can lead to more accurate precipitation forecasts of benefit to societal activities including water management.