CAREER: Water and Energy Cycle Research and Education from the Stable Water Isotope Budget Near a Tall Tower in the Colorado Front Range

该项目将主要在300米长的博尔德大气天文台观测和分析水蒸气和降水的稳定同位素组成。测量将使用最近才出现的光学测量技术进行，该技术允许在实际基础上进行连续的现场观测。将进一步测量塔顶和塔底降水水流星的大小分布，并测量表面感热和潜热通量(使用声波风速计和高速湿度计)和土壤热通量(使用导电板)。这些测量将补充现有的一氧化碳(CO)和二氧化碳(CO2)测量以及塔台的气象学，水蒸气测量将在与CO和CO2测量相同的高度进行，分别在22米、100米和300米处。此外，该地区几所中学的学生将测量降水和土壤水的同位素组成，并进行同位素组成分析。中学还将配备气象观测站，学生将进行气象测量，并接受大气过程和同位素水文科学的指导。这项研究试图评估1)降雨蒸发(VIGA)在控制夏季边界层的同位素组成和湿度方面的作用，2)通过对地面潜热的蒸腾分数的同位素限制，对地表能量和水通量的分配，以及3)水同位素测量与其他气体测量，如二氧化碳浓度，在多大程度上改善了对地面和上覆大气之间气体交换的估计。降水和水蒸气的同位素组成包含大量有用的信息，包括海洋上发生蒸发的温度、陆地上的蒸发蒸腾作为后续降水来源的程度(即陆地-大气耦合的强度)、大气中水蒸气的输送途径以及陆地和大气之间的痕量气体交换(包括二氧化碳)的强度。但是，决定同位素组成的众多因素使得提取有用的信息变得困难，特别是考虑到我们对一些物理过程的有限的定量理解。因此，在该项目下进行的研究将有助于消除决定同位素组成的因素，并解开其中所包含的有价值的气候学信息，从而为气候科学界服务。此外，中学生参与该项目将通过提供早期接触科学研究的机会，服务于周围社区的普通公众，包括代表不足的群体。科罗拉多大学还将开展教育活动，涉及研究生和本科生，包括一个项目，工程专业的学生设计和制造一个机械装置来收集雨雪样本。

This project will observe and analyze the stable isotope composition of water vapor and precipitation, primarily at the 300 meter Boulder Atmospheric Observatory tower. The measurements will be made using an optical measurement technology which has only recently become available, and which allows continuous in-situ observations to be made on a practical basis. Further measurements will be taken of the size distribution of precipitation hydrometeors at the top and bottom of the tower, as well as measurements of the surface fluxes of sensible and latent heat (using a sonic anemometer and a high speed hygrometer) and soil heat flux (using a conductive plate). These measurements will complement existing measurements of carbon monoxide (CO), and carbon dioxide (CO2), and meteorology at the tower, and the water vapor measurements would be taken at the same heights as the CO and CO2 measurements, at 22, 100, and 300 meters. In addition, measurements of the isotopic composition of precipitation and soil water would be taken by students at several middle schools in the region and analyzed for isotopic composition. The middle schools will also be supplied with meteorological observing stations, and students will take meteorological measurements and receive instruction on atmospheric processes and the science of isotope hydrology. The research seeks to evaluate 1) the role of rainfall evaporation (virga) in controlling the isotopic composition and humidity of the summertime boundary layer, 2) the partioning of the surface energy and water fluxes, through isotopic constraints on the transpiration fraction of surface latent heating, and 3) the degree to which pairing water isotope measurements with other gas measurements, such as CO2 concentration, yield improved estimates of gas exchange between the surface and the overlying atmosphere. The measurements will be used to constrain and validate simulations from the Community Land and Community Atmosphere Models.The isotopic composition of precipitation and water vapor contains a wealth of useful information, including the temperature at which evaporation occurs over the ocean, the extent to which evapotranspiration over land serves as a source for subsequent precipitation (i.e. the strength of the land-atmosphere coupling), the pathways of water vapor transport in the atmosphere, and the strength of trace gas exchange (including CO2) between land and atmosphere. But the multitude of factors determining isotopic composition makes it difficult to extract the useful information, particularly given our limited quantitative understanding of some of the physical processes. Research conducted under this project will thus serve the climate science community by helping to deconvolve the factors determining isotopic composition, and unlock the valuable climatological information contained in it. In addition, the participation of middle school students in the project will serve the general public, including underrepresented groups, in surrounding communities by offering an early exposure to scientific research. Educational activities will also take place at the University of Colorado involving graduate and undergraduate students, including a project in which engineering students design and build a mechanical device to collect rain and snow samples.