Collaborative Research: Sublimation of Snow (SOS)

积雪在水资源中起着至关重要的作用，特别是对于那些从季节性山地积雪融化中获得水的地区。然而，融化并不是积雪枯竭的唯一方式。雪的升华是指雪直接变成水蒸气的过程。升华的影响还没有被很好地理解，导致升华或多或少的具体大气条件也没有被很好地理解。该项目将通过在2022-23年冬季在科罗拉多州部署一套先进的仪器来帮助解决与这些主题相关的问题。这个项目的结果将是一个数据集，可以用来确定数值模型是否正确地处理升华，如果不是，如何改进它们。研究小组将与水资源管理者等相关利益攸关方团体进行沟通，并制作简短的视频，用通俗易懂的语言解释困难的概念。学生将直接参与实地活动，从而培养下一代观测和数据分析科学家。研究小组将于2022-23年冬季在科罗拉多州的Kettle Ponds进行雪升华（SOS）实地活动。雪升华在水资源中起着重要作用，但控制升华速率的物理学尚未完全了解。该项目将重点关注风在升华中的作用，既包括在湍流至关重要的低风条件下，也包括在吹雪因素的大风条件下。SOS现场活动是嵌入在一个更大的美国能源部赞助的名为地面大气综合现场实验室（SAIL）的活动中，该活动将提供来自雷达和激光雷达的遥感测量。SOS将提供四个通量塔（NCAR综合地表通量系统，ISFS）用于湍流和潜热通量测量，以及一些其他仪器，这些仪器将提供雪深、密度、含水量、土壤和积雪温度以及吹雪特性。将解决三个关键的科学问题：在复杂地形中，是什么决定了近地表边界层的特征，这些特征是如何随时间演变的？在一个冬季，不同的边界层状态发生的频率有多高，每次发生多少雪升华，这如何影响整个季节的质量和能量平衡？什么样的测量和分析策略对于量化山谷中的雪升华是最稳健的？该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Snowpack plays a vital role in water resources, especially for regions that get water from the seasonal melt of mountain snowfall. However, melting is not the only way that the snowpack is depleted. Sublimation of snow refers to the process by which snow changes directly to water vapor. The impact of sublimation is not well understood, nor are the specific atmospheric conditions that lead to more or less sublimation. This project will help to address questions related to those topics by deploying a set of advanced instrumentation in Colorado in the 2022-23 winter season. The result of this project will be a dataset that can be used to determine whether numerical models are handling sublimation correctly, and if not, how to improve them. The research team will communicate with relevant stakeholder groups, such as water managers, and develop short videos that explain difficult concepts in clear language accessible to the general public. Students will be directly involved in the field campaign, thereby training the next generation of observational and data analysis scientists.The research team will conduct the Sublimation of Snow (SOS) field campaign in Kettle Ponds, Colorado during the 2022-23 winter season. Snow sublimation plays a significant role in water resources but the physics that govern rates of sublimation are not fully understood. This project will focus on the role of wind in sublimation, both in low-wind conditions where turbulence is crucial, and in higher-wind conditions when blowing snow factors in. The SOS field campaign is embedded within a larger DOE-sponsored campaign called the Surface Atmosphere Integrated Field Laboratory (SAIL) which will provide remote sensing measurements from radars and lidars. SOS will contribute four flux towers (NCAR Integrated Surface Flux Systems, ISFS) for turbulence and latent heat flux measurements, along with a number of other instruments that will provide snow depth, density, and water content, soil and snowpack temperatures, and blowing snow characteristics. Three key science questions will be addressed: What governs the characteristics of the near-surface boundary layer over snow in complex terrain, and how these characteristics evolve through time? Over a winter season, how frequently do different boundary layer regimes occur, how much snow sublimation occurs during each, and how does this affect the total seasonal mass and energy balance? What measurement and analysis strategies are most robust for quantifying snow sublimation in a mountain valley?This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.