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米的博尔德大气观测塔上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，这种技术可以在实际基础上进行连续的现场观测。 还将进一步测量塔顶部和底部的降水水凝物的大小分布，并测量表面的显热和潜热通量（使用声波风速计和高速湿度计）和土壤热通量（使用导热板）。 这些测量将补充塔上现有的一氧化碳（CO）和二氧化碳（CO2）以及气象测量，水蒸气测量将在与CO和CO2测量相同的高度（22，100和300米）进行。 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，并分析同位素组成。 还将向中学提供气象观测站，学生将进行气象测量，并接受关于大气过程和同位素水文学的教育。 该研究旨在评估1）降雨蒸发（virga）在控制夏季边界层的同位素组成和湿度中的作用，2）通过对表面潜热蒸腾分数的同位素约束来分配表面能量和水通量，以及3）将水同位素测量与其他气体测量（如CO2浓度）配对的程度，改进了地表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了大量有用的信息，包括海洋蒸发发生时的温度、陆地蒸散作为随后降水来源的程度（即陆-气耦合的强度）、水汽在大气中的输送途径以及陆-气间微量气体（包括CO2）交换的强度。 但是，决定同位素组成的因素众多，很难提取有用的信息，特别是考虑到我们对某些物理过程的定量理解有限。 因此，通过对同位素组成的决定性因素进行解卷积，揭示其中蕴含的宝贵气候学信息，为气候科学界服务。此外，通过中学生参与该项目，为周边社区的普通公众（包括代表性不足的群体）提供早期接触科学研究的机会。 教育活动也将在科罗拉多大学举行，涉及研究生和本科生，其中包括一个工程专业学生设计和建造一个收集雨雪样本的机械装置的项目。

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.