Collaborative Research: Feedbacks between Marine Stratiform Cloud, Atmospheric Circulation and Temperature on Decadal Timescales and in Anthropogenic Change

合作研究：海洋层云、大气环流和温度在十年时间尺度和人为变化中的反馈

• 批准号: 0946225
• 负责人: Amy Clement
• 金额: $ 43.01万
• 依托单位: University of Miami
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-01-01 至 2012-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0946225&HistoricalAwards=false
• 关键词: Collaborative; Research; Feedbacks; between; Marine

Marine stratus clouds (MSC) are low clouds that form in the subtropics off the west coast of continents, and the resulting "stratus decks" cool the earth by reflecting sunlight back to space. The fate of the stratus decks in a warming climate could be a key factor in determining the earth's climate sensitivity, or how much the planet will warm for a given increase in atmospheric greenhouse gases. If the stratus decks expand, or become more persistently cloudy, the resulting increase in reflected sunlight would have a cooling effect and counteract some of the greenhouse warming (a "negative feedback"). But if they contract or become less cloudy global warming could become considerably enhanced (a "positive feedback"). At present the sign of the MSC feeback is not known and the physical mechanisms which determine the sign of the feedback are not well understood.This research project will address the MSC feedback through an examination of relationships between MSC, atmospheric circulation, and temperature, occuring both in observations and in model simulations. Preliminary work by the principal investigators has shown that decadal fluctuations are detectable in cloud datasets. Furthermore, these signals reveal the sensitivity of the clouds to shifting environmental conditions on timescales relevant for climate change, and can serve as a important test of model simulations of cloud variability. Research under this grant will build on the preliminary work by 1) examining observed long-term variability in subtropical regions around the globe using multiple, independent cloud and meteorological datasets; 2) evaluating the simulation of MSC in global climate models through the use of observed cloud-meteorology relationships, and assessing the reliability of model cloud feedbacks and projected cloud and climate changes; and 3) using the current and upcoming versions of the NCAR global climate model (GCM) to carry out experiments quantifying MSC feedbacks. The work is designed to test three linked hypotheses: 1) Subtropical MSC exerts a local and regional positive feedback on SST and atmospheric circulation; 2) This feedback substantially contributes to decadal variability in the local and regional atmosphere-ocean system; and 3) Changes in subtropical MSC under long-term anthropogenic warming will be primarily associated with dynamical processes (changes in atmospheric circulation) rather than thermodynamical processes (changes in lapse rate).The work performed under the grant will be of broad interest because of the need for better estimates of the degree to which the world will warm in response to greenhouse gas increases. In addition, the project will enhance infrastructure for research and education by fostering a research collaboration between the University of Miami and the University of California, San Diego. The work will also support two graduate students. Outreach activities will be conducted at both universities, including activities to encourage middle-school girls to pursue careers in science (in Miami), and activities at a summer school for high school students (in San Diego).

海洋地层云（MSC）是在大陆西海岸的亚热带中形成的低云，由此产生的“ Stratus甲板”通过将阳光反射回太空来冷却地球。 在温暖气候下，Stratus甲板的命运可能是确定地球气候敏感性的关键因素，或者地球将使大气温室气体增加的地球变暖。 如果Stratus甲板膨胀或变得更加持久地云彩，那么反射的阳光的增加将产生冷却效果并抵消一些温室变暖（“负反馈”）。 但是，如果他们收缩或变得越来越多的多云全球变暖可能会大大增强（“积极的反馈”）。 目前，尚不清楚MSC费用的迹象，确定反馈迹象的物理机制尚不清楚。该研究项目将通过检查MSC，大气循环和温度之间的关系来解决MSC的反馈。在观测和模型模拟中。 首席研究人员的初步工作表明，在云数据集中可以检测到衰老的波动。 此外，这些信号揭示了云对与气候变化相关的时间尺度转移环境条件的敏感性，并可以作为云变异性模型模拟的重要测试。根据1）使用多个独立的云和气象数据集研究了该赠款下的研究基于初步工作的研究； 2）通过使用观察到的云现象关系，评估全球气候模型中MSC的模拟，并评估模型云反馈以及投影云和气候变化的可靠性； 3）使用NCAR全球气候模型（GCM）的当前和即将发布的版本来量化MSC反馈的实验。 这项工作旨在检验三个链接的假设：1）亚热带MSC对SST和大气循环发挥局部和区域正反馈； 2）这种反馈在很大程度上导致了局部和区域氛围 - 海洋系统的衰老变异； 3）在长期人为变暖下，亚热带MSC的变化主要与动态过程（大气环流的变化）而不是热力学过程（失败率的变化）有关。赠款下执行的工作将具有广泛的兴趣，因为需要更好地估计全世界对温室气体的增长程度的估计。 此外，该项目将通过促进迈阿密大学和加利福尼亚大学圣地亚哥分校之间的研究合作来增强研究和教育的基础设施。 这项工作还将支持两名研究生。 外展活动将在两所大学进行，包括鼓励中学女孩从事科学职业的活动（迈阿密），以及在一所暑期学校（圣地亚哥）的暑期学校的活动。