Forced and Natural Turbulence Allowing Studies of Turbulent anIsotropic Conditions (FaNTASTIC- 1)

大气边界层（ABL）的下部，即距地球表面约300米的大气部分，随着夜间变冷经历了快速转变，导致相干涡旋的时间和空间特性迅速演变。该项目将使用一个独特的、高度仪器化的观测区域，详细观察这些变化（涡流）。一套原位和遥感仪器将放置在200个涡轮机的风电场（强迫湍流）内，另一套放置在约22公里外的自然湍流相匹配的景观中。研究小组将以先前的建模和测量经验为基础，通过比较强迫湍流和自然湍流，对边界层产生新的认识。智力优势：本研究的创新之处在于，涡轮机或其他景观结构产生的湍流与自然景观（如玉米/大豆田）相比，具有明显不同的光谱特征和随后对大气交换过程的明显影响。相干涡旋，被认为是ABL的中心特征，不能被莫宁-奥布霍夫相似理论（MOST）正确地表示。高分辨率的原位测量将为稳定条件下的MOST提供物理替代，这反过来将提高天气预报和模拟的技能，特别是在稳定的分层条件下。该项目有三个目标：通过使用高分辨率近地表湍流测量塔，战略性地放置两个高塔和一个雷达，表征各向异性和大连贯湍流涡流（自然和强迫）。它们是如何在早夜过渡（EET）期间和之后开始的？当ABL在稳定分层条件下进化时，哪些因素有助于节能？目标2。采用多分辨率分解（MRD）和小波变换方法来识别与高频（局部湍流）对湍流协方差的影响相比，低频（如中尺度）对相干结构的影响最小的事件。这些方法如何帮助从那些受独特的强迫（涡轮机）或中尺度（例如，重力波、表面非均质性和地形）影响的影响中精炼纯粹由局部湍流驱动的表面通量的描述？目标3。结合目标1和目标2的测量和分析，以及WRF和其他模式的中尺度和LES模拟，对相干涡演化和地表附近湍流势能（TPE）在响应ABL EET辐射变化中的作用有了新的认识。在不同的分层水平下，模型对TKE和TPE相对震级的敏感性是什么？在稳定分层中，选择相干涡长尺度应遵循哪些原则？更广泛的影响：1)本研究提高了对科学的认识，将产生广泛的科学、社会和经济影响。研究成果将跨越多个STEM学科，为国家重点研究领域提供新的基础认识。2)学生学习与培训。这项研究的结果将加强各级学生的教育和经验，重点是培养具有学科深度和跨越学科界限的能力，能够在团队中有效工作的科学家。3)服务不足人群。在研究生阶段，研究团队将利用爱荷华州立大学NSFIGERT奖的积极计划，从波多黎各大学招募学生。在本科阶段，该团队将与IINSPIRE-LSAMP联盟合作，ISU是该联盟的合作机构。4) K-14交战。该研究团队将与ISU的新风能学生组织（WESO）合作，该组织在K-12和社区大学层面都有积极的联系。5)双向师徒关系。在EPSCoR、IGERT、MRI和REU资助的当前和最近的ISU nsf资助的风能项目的基础上，研究团队建立了近乎对等的指导关系，认识到性别、种族、个人兴趣和气质在配对成功中的作用。

The lower part of the atmospheric boundary layer (ABL) - the part of the atmosphere extending ~300 m from Earth's surface - undergoes rapid transitions with nocturnal cooling, resulting in rapidly evolving temporal and spatial properties of coherent eddies. Using a unique and highly instrumented observation region, this project will observe these variations (eddies) in detail. One set of in-situ and remote sensing instruments will be sited inside a 200-turbine wind farm (forced turbulence) and another set ~22 km away in a matched landscape of natural turbulence. The research team will build on prior modeling and measurement experience to produce new understanding of the boundary layer by comparing forced and natural turbulence.Intellectual Merit:The innovativeness of this study derives from the fact that turbulence generated by turbines or other landscape structures has a distinctly different spectral signature and subsequent distinct influence on atmospheric exchange processes than do natural landscapes, such as fields of corn/soybean. Coherent eddies, known to be the central feature of the ABL, are not represented correctly by Monin-Obukhov Similarity Theory (MOST). The high-resolution in situ measurements will provide a physical alternativeto MOST for stable conditions, which in turn will improve the skill of weather forecasts and simulations, particularly under stably stratified conditions. The project has three objectives: Objective 1. Characterize anisotropic and large coherent turbulence eddies (natural and forced) by use of a high-resolution near-surface turbulence-measurement tower, strategically placed two tall towers, and a sodar. How are they initiated during and after the early evening transition (EET)? What are the contributing factors to energy conservation as the ABL evolves under stably stratified conditions? Objective 2. Employ multi-resolution decomposition (MRD) and wavelet transform methods to identify events of coherent structures that show minimal low frequency (e.g., mesoscale) compared to high frequency (local turbulence) influences on turbulent covariances. How can these methods help refine descriptions of surface fluxes driven purely by local turbulence from those influenced by uniquely forced (turbines) or mesoscale (e.g., gravity waves, surface heterogeneities, and terrain) influences? Objective 3. Combine measurements and analyses of Objectives 1 and 2, together with mesoscale and LES simulations with WRF and other models, to develop new understanding of coherent eddy evolution and the role of turbulent potential energy (TPE) near the surface in response to radiative changes in the EET of the ABL. What is the model sensitivity to the relative magnitudes of TKE and TPE under various levels of stratification? What principles should guide the choice of coherent eddy length scales for simulating flow in stable stratification?Broader Impacts:1) Improved Scientific Understanding from this research will have broad scientific, societal and economic ramifications. The research results will cross-cut many STEM disciplines and provide new fundamental understanding in research areas of high national priority.2) Student Learning and Training. Results from the study will enhance the education and experience for students at all levels, with emphasis on developing scientists with disciplinary depth and ability to reach across disciplinary boundaries, capable of working effectively in teams.3) Outreach to Underserved Populations. At the graduate level the research team will take advantage of the Iowa State University's NSFIGERT award's aggressive plan for recruiting students from the University of Puerto Rico. At the undergraduate level, the team will collaborate with the IINSPIRE-LSAMP Alliance, of which ISU is a partner institution.4) K-14 Engagement. The research team will partner with ISU's new Wind Energy Student Organization (WESO) that has active outreach to both the K-12 and community college level.5) Bi-Directional Mentoring Hierarchy. Built on current and recent ISU NSF-funded wind energy projects under EPSCoR, IGERT, MRI, and REU, the research team has established near-peer mentorships recognizing roles of gender, ethnicity, personal interests, and temperament in pairing-for-success.