Lake Breeze System of the Great Salt Lake

浅层热驱动的风环流通常沿着广阔的海岸线发展，在海岸线上，太阳能吸收、蒸发和由此产生的感热率的水平梯度往往相当大。相关的海风发展沿着广阔的（通常是静止的）海岸线，边界是平坦的地形已经得到了很好的描述。这些环流调节地面空气温度和边界层混合，从而影响沿海地区的气象和空气质量。不太清楚的是，在地形陡峭和/或海岸线位置多变的情况下，湖风形成的结构和动力学，由于干旱地区径流湖泊的水位波动，容易发生这种情况。这就是大盐湖（GSL）的情况，它与盐湖城的主要城区接壤，在过去的十年里，它的水位和海岸线的相关投影都发生了显著的变化。先前的工作已经描述了GSL湖风形成的基本原理，包括其频率和首选季节性的统计数据，但主要局限于二维（基于表面的）视角。这项新研究将(1)分析10年的存档观测数据，其中包括来自相对密集的地面中网（MesoWest）及其前身“犹他中网”（Utah Mesonet）和终端多普勒天气雷达（TDWR）站点的数据，以建立一个更完整的GSL湖风行为的三维气候学；(2)收集和分析常规和特殊观测资料（包括上述两个移动气球发射平台的基于雷达的低层气流、风和热力学剖面图，以及多达8个便携式地面气象站的选择性定位测量），以研究2008年秋季约10次湖微风事件；(3)结合大涡模拟（LES）和使用WRF（天气研究与预报模式）的传统中尺度模拟，探讨这些环流对湖岸范围变化和大尺度强迫引起的地表加热变化的响应。这项工作的智力价值在于推进了我们对海岸线附近陡峭地形下热驱动环流的基本理解，并增加了对干旱环境中控制湖风发展过程的认识。它还将详细描述区域尺度天气与GSL生态系统之间的一些复杂相互关系，并更好地量化大气环流对下垫面状态的自然和人为变化的潜在敏感性。这项工作的更广泛的影响将包括对更准确地模拟当地/区域天气和对人口稠密的沿海地区的城市气象的影响的贡献（包括，例如，影响能源需求的每日最高温度预报和影响空气质量的通风/混合变化）。将支持培训一名研究生和博士后研究助理设计和执行协调的LES和传统中尺度模拟，并将支持多达20名本科生直接参与规划和开展与GSL相邻的湖风锋附近的实地数据收集。

Shallow thermally-driven wind circulations commonly develop along extensive coastlines, across which horizontal gradients in solar absorption, evaporation and resultant sensible heating rates are often quite large. Associated sea breeze development along extensive (and generally stationary) coastlines bordered by flat terrain has been well described. These circulations modulate surface air temperatures and boundary-layer mixing, and thus impact both meteorology and air quality in the coastal zone. Less well understood are the structure and dynamics underlying lake-breeze formation in the presence of steep orography and/or variable coastline location, as prone to occur owing to fluctuation of water levels in runoff-fed lakes within arid regions. Such is the situation for the Great Salt Lake (GSL), which is bordered by the major urban area of Salt Lake City and has undergone marked changes in water level and associated projection of its coastline over the past decade. Prior work has described the rudiments of GSL lake breeze formation, including statistics of its frequency and preferred seasonality, but have been confined mainly to a two-dimensional (surface-based) perspective. This new study will (1) analyze archived observations over a 10-year period, which include data from a relatively dense surface mesonetwork ('MesoWest', and its predecessor the 'Utah Mesonet') and a terminal Doppler weather radar (TDWR) site, to develop a more complete 3D climatology of GSL lake-breeze behavior; (2) collect and analyze both routine and special observations (including aforementioned radar based views of low-level airflow, wind and thermodynamic profiles from two mobile balloon-launch platforms, and selectively positioned measurements from up to eight portable surface meteorological stations) to examine ~10 lake-breeze events during Autumn 2008; and (3) apply a combination of large-eddy simulation (LES) and more traditional mesoscale simulations using WRF (the Weather Research and Forecasting model) to explore the response of these circulations to variations in surface heating induced by varying lakeshore extent and large-scale forcing.The intellectual merit of this work rests in advancing our basic understanding of thermally-driven circulations along coastlines in the presence of nearby steep terrain, and increased knowledge of processes that control the development of lake breezes in arid environments. It will also provide a detailed description of some of the complex interrelationships between regional-scale weather and the GSL ecosystem, and better quantify potential sensitivity of atmospheric circulations to both natural and anthropogenic changes in the underlying surface state. Broader impacts of this work will include contributions toward more accurate simulation of local/regional weather and impacts on urban meteorology in densely populated coastal zones (including, for example, daily maximum temperature forecasts impacting energy demands and changes in ventilation/mixing impacting air quality). Training of a graduate student and postdoctoral research associate in the design and execution of coordinated LES and traditional mesoscale simulations will be supported, as will involvement of up to 20 undergraduate students to be directly involved in planning and conducting field data collection in the vicinity of lake-breeze fronts adjacent to the GSL.