CAREER: The Mesoscale Climate Dynamics of Rocky Mountain Snowpack Depletion

山区积雪的地表反照率反馈（SAF）是中纬度地区对大尺度气候变率和变化的区域响应的主要影响因素之一。在全球尺度上，详细的分析揭示了SAF的控制因素和全球气候模式（GCMs）之间SAF量级的传播来源。虽然在复杂地形上的区域气候模式（RCM）模拟表明SAF具有实质性的区域效应，但尚未对区域SAF进行详细的定量分析。该项目将使用WRF模型在落基山脉（后来是美国大陆）的高分辨率RCM模拟中量化和诊断SAF。它们包括8年再分析强迫控制模拟和8年伪全球变暖（PGW）模拟，其中再分析边界条件受到温室强迫下GCM预测的月平均变化的扰动。这一框架允许在不考虑大尺度环流和风暴变化的情况下对气候变化的热力学和中尺度机制进行清晰的诊断。分析将包括：(i) SAF的量化及其对各种物理过程的贡献：SAF将通过线性反馈分析和抑制SAF的RCM模拟与其他强迫和反馈分离。分析了积雪和雪变质作用的相对作用、大气对地表反照率变化的遮蔽作用以及大气平流的作用等对南亚气旋强度的控制机制。（ii）评估模拟积雪和反照率：RCM输出将根据MODIS仪器（包括新的MODSCAG雪产品）提供的高分辨率遥感进行评估，以严格测试模拟SAF的真实性并确定偏差来源。（三）检查SAF和区域尺度环流之间的相互作用：这将包括确定平流在平衡辐射扰动方面的作用，以及辐射扰动在改变热驱动的中尺度环流方面的作用。（iv）与其他山脉的比较、强迫情景和模式参数化：将使用不同模式配置的额外模拟分析来了解地理环境如何调节SAF。它还将用于检查有和没有大尺度环流或雪尘强迫变化的模拟之间SAF的差异。研究生阶段的教育影响将包括对学生的指导和培训。在本科阶段，山区环境科学课程将以项目和实地观测的RCM产出丰富内容。在高中阶段，将为当地学生开展年度课堂访问和为期一周的天气和气候夏令营。这些项目将服务于STEM领域少数族裔人口较多的城市地区。夏令营将通过讲座、演示、动手实验室体验和到当地山顶天文台的互动实地考察来吸引学生。学生将被介绍到大学环境，职业选择和一系列的榜样。这将有助于促进、激励和招募学生，以便将来在大气科学和STEM领域学习和就业。

The surface-albedo feedback (SAF) from mountain snow cover is one of the dominant influences on the regional-scale response to large-scale climate variability and change in the mid-latitudes. At global scales, detailed analyses have illuminated the controls on the SAF and sources of spread in SAF magnitude between global climate models (GCMs). While regional climate model (RCM) simulations over complex terrain suggest substantial regional effects of the SAF, no detailed quantitative analysis of the regional SAF has been undertaken. This project will quantify and diagnose the SAF in high-resolution RCM simulations over the Rocky Mountains (and later the continental United States) using the WRF model. They include 8-year reanalysis-forced control simulations and 8-year pseudo-global-warming (PGW) simulations, wherein reanalysis boundary conditions are perturbed by monthly mean changes predicted by a GCM under greenhouseforcing. This framework allows for clean diagnosis of thermodynamic and mesoscale mechanisms of climate change in isolation from changes in large-scale circulations and storminess. Analysis will include: (i) Quantification of the SAF and its contributions from various physical processes: The SAF will be separated from other forcings and feedbacks via linear feedback analysis and via RCM simulations with a suppressed SAF. The mechanisms controlling the strength of the SAF will be diagnosed including: the relative roles of snow cover and snow metamorphism changes, the atmosphere masking of surface albedo changes, and the role of atmospheric advection. (ii) Evaluation of simulated snow cover and albedo: RCM output will be evaluated against high-resolution remote sensing provided by the MODIS instrument (including the new MODSCAG snow product) to critically test the realism of the simulated SAF and identify sources of bias. (iii) Examination of the interactions between the SAF and regional-scale circulations: This will include a determination of the role of advection in balancing radiative perturbations and the role of radiative perturbations in altering thermally driven mesoscale circulations. (iv) Comparison with other mountain ranges, forcing scenarios, and model parameterizations: Analysis of additional simulations with different model configurations will be used to understand how geographic setting modulates the SAF. It will also be used to examine differences in the SAF between simulations with and without changes in large-scale circulations or dust-on-snow forcing.Educational impacts at the graduate level will include mentoring and training of a student. At the undergraduate level, a course on the environmental science of mountainous regions will be enriched with RCM output from the project and field observations. At the high school level, annual classroom visits and weeklong summer camps on weather and climate for local students will be developed. These programs will serve urban districts with high populations of minorities underrepresented in the STEM fields. The camps will engage students through lectures, demonstrations, hands-on laboratory experiences, and an interactive field trip to a local mountaintop observatory. Students will be introduced to the university environment, career options, and a range of role models. This will serve to enable, excite, and recruit students for future study and employment in the atmospheric sciences specifically and STEM in general.