CAREER: The Lapse Rate Feedback and Other Mechanisms of High-Latitude Climate Change

温室气体变暖效应的模型模拟通常显示，极地冰帽上的温度上升幅度比全球其他地区更大。这种“极地放大”现象与北极地区气温急剧上升相一致，这对该地区的人类和自然系统造成了各种严重影响。因此，极地放大的研究具有实用和科学意义，因为人们对极地地区的变暖和融化知之甚少，也很难预测，但却具有世界性的影响。在这个职业奖项的教育和推广部分，PI与本科生合作开发计算机游戏，可以用来向中学生介绍环境科学。这项工作的基础是研究表明，适当设计的游戏可以用来向学生介绍科学发现，通过制定、测试和重新评估假设来诱使他们探索虚拟世界。已经开发了游戏来培养其他学科的科学思维，包括分子生物学和天体生物学。这项工作对广大游戏玩家(他们中的许多人可能对传统的STEM课堂作业兴趣有限)和开发该游戏的跨学科本科生团队都产生了更广泛的教育影响。该项目的科学焦点是错误率反馈，即温度随高度变化的方式影响给定二氧化碳(CO2)增加时发生的变暖总量。在热带地区，变暖是最严重的，高层的温度上升更大，高空变暖有助于大气更有效地冷却到太空，以平衡二氧化碳的热量捕获效应。但极地冰帽通常更靠近地表变暖，部分原因是冰雪覆盖的减少暴露了下面较暗的陆地和海洋表面。这种底部的重度变暖需要更大的温度升高来平衡二氧化碳的增加，而不是在所有层面上均匀分布的情况下，因此它有助于极地放大。极地衰减率反馈的逻辑是合理的，其效果已经在模型中得到证明，但反馈的强度尚不清楚。一个考虑因素是，进入极地冰盖的能量传输可能会抵消海底的重量，因为大部分传输都发生在高空。但能量输送的净影响尚不清楚，因为干静态能量的输送预计会随着变暖而减少，而潜能则随着空气变得更加潮湿而增加。近地表增温引起的低云变化也可能减弱极地转折率反馈的增温效应。这些影响是通过使用不同复杂程度的模型层次结构进行模拟来检验的。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Model simulations of the warming effect of greenhouse gases typically show greater temperature increases over the polar caps than the rest of the globe. This "polar amplification" is consistent with the dramatic temperature increase seen in the Arctic, which has caused a variety of severe impacts on the human and natural systems of the region. Research on polar amplification is thus of practical as well as scientific interest, as the warming and thawing of the polar regions is poorly understood and difficult to predict yet has worldwide consequences.In the education and outreach component of this CAREER award the PI works with undergraduate students to develop computer games that can be used to introduce middle school students to environmental science. The work is based on research showing that appropriately designed games can be used to introduce students to scientific discovery, enticing them to probe a virtual world through formulating, testing, and reevaluating hypotheses. Games have been developed to foster scientific thinking in other disciplines including molecular biology and astrobiology. The work has educational broader impacts both for the broad audience of game players, many of whom may have limited interest in traditional STEM classwork, and for the cross-disciplinary team of undergraduate students who develop the game.The scientific focus of the project is the lapse rate feedback, in which changes in the way temperature varies with height affect the total amount of warming that occurs for a given increase in carbon dioxide (CO2). In the tropics the warming is top heavy, with greater temperature increases at upper levels, and the greater warming aloft helps the atmosphere cool to space more effectively to balance the heat trapping effect of the CO2. But the polar caps typically warm more near the surface, in part due to reductions in ice and snow cover which expose the darker land and sea surface below. This bottom heavy warming requires a greater temperature increase to balance the CO2 increase than would be required if the warming were distributed equally at all levels, thus it contributes to polar amplification.The logic of the polar lapse rate feedback is sound and the effect has been demonstrated in models, but the strength of the feedback is unclear. One consideration is that energy transport into the polar caps could work against bottom-heaviness given that much of the transport occurs aloft. But the net effect of energy transport is unclear as the transport of dry static energy is expected to decrease with warming while latent energy increases as the air becomes more moist. Low cloud changes due to near-surface warming may also reduce the warming effect of the polar lapse rate feedback. These effects are examined through simulations using a hierarchy of models at varying levels of complexity.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.