CEDAR: Polar Mesospheric Clouds Using the Whole Atmosphere Community Climate Model 3

CEDAR：使用整个大气群气候模型 3 的极地中层云

• 批准号: 0737705
• 负责人: Cora Randall
• 金额: $ 31.26万
• 依托单位: University of Colorado at Boulder
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-12-15 至 2011-11-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0737705&HistoricalAwards=false
• 关键词: CEDAR; Polar; Mesospheric; Clouds; Using

This project will combine global modeling with ground-based and satellite observations of polar mesospheric clouds (PMCs) to investigate formation, growth, and dissipation mechanisms of the clouds. PMCs occur at a threshold temperature and water vapor pressure and grow exponentially with reduced temperatures, providing highly sensitive indicators of mesospheric conditions. Anthropogenic inputs, including water vapor from space shuttle exhaust and long-term increases in atmospheric methane and carbon dioxide, are suggested causes for the recent appearance of these clouds (observed every summer since 1885, but never prior) and are predicted to produce long-term changes in their brightness and occurrence. Whether such long-term changes have yet been observed is a question currently debated, due to large natural variability. Natural influences on PMC occurrence and brightness include the solar cycle, volcanic eruptions, and dynamical perturbations. The goals of this proposal are to incorporate PMC and sulfate aerosol microphysics into a global chemistry climate model extending through the mesosphere and to investigate the influences of volcanic perturbations and space shuttle exhaust on PMC formation. Attainment of these goals will facilitate future investigations of the separate and coupled effects of anthropogenic influences, solar variability, volcanic sulfate aerosol, and dynamics. The work will utilize the National Center for Atmospheric Research (NCAR) Whole Atmosphere Community Climate Model 3 (WACCM3), with substantial focus on validating mesospheric dynamics and chemistry in the model via comparisons with ground-based and satellite data. The project is a continuation of current collaborative efforts to incorporate microphysics for a number of aerosol types, including sulfate aerosol and Polar Stratospheric Clouds, into the WACCM3 model. Of particular interest is investigation of a recent hypothesis on the existence of a mesospheric sulfate aerosol layer. This new source of nuclei for PMCs explains the dramatic decrease in PMC occurrence following the 1991 eruption of Mt. Pinatubo. WACCM3 with microphysics will be run with and without inclusion of volcanic input to better understand the influence of each on PMC variability. This will be the first time PMCs have been modeled microphysically in three dimensions with interactive dynamics and chemistry, enabling further study of natural and anthropogenic influences on the clouds. The broader impacts of the project include the networks and partnerships it will foster, the broad dissemination of results, public outreach, and benefits to society. The project will integrate research and education by offering graduate students opportunities to study the upper atmosphere. This work will be part of a recently instituted program in which a number of scientists and students are learning the WACCM model so that it can be applied to the various scientific issues, in collaboration with scientists at NCAR. Incorporation of PMC microphysics into WACCM3 will provide a new tool to the upper atmospheric research community, enabling scientists to more accurately test theories about PMC formation and evolution, interpret observations, and understand mesospheric change and coupling to lower altitudes. Websites will be developed to describe current understanding regarding PMCs and global change, aimed at both students and the general public.

本计画将结合全球联合收割机与极地中层云的地面与卫星观测，以研究云的形成、成长与消散机制。PMC发生在临界温度和水蒸气压力下，并随温度降低呈指数增长，提供了中间层条件的高度敏感指标。人类活动的输入，包括航天飞机排气产生的水蒸气和大气中甲烷和二氧化碳的长期增加，被认为是最近出现这些云的原因（自1885年以来每年夏天都观察到，但从未有过），并预测会产生长期的亮度和发生率变化。由于大的自然变异性，是否观察到这种长期变化是目前争论的一个问题。对PMC发生和亮度的自然影响包括太阳活动周期、火山爆发和动力学扰动。该建议的目标是将PMC和硫酸盐气溶胶微物理学纳入一个全球化学气候模式，延伸到中间层，并调查火山扰动和航天飞机排气对PMC形成的影响。这些目标的实现将有利于未来的调查的单独和耦合的影响，人为的影响，太阳的变化，火山硫酸盐气溶胶和动力学。这项工作将利用国家大气研究中心（NCAR）的全大气社区气候模型3（WACCM 3），重点是通过与地面和卫星数据的比较来验证模型中的中间层动力学和化学。该项目是当前合作努力的继续，目的是将硫酸盐气溶胶和极地平流层云等若干气溶胶类型的微物理学纳入WACCM 3模型。特别令人感兴趣的是调查最近的一个假设存在的中间层硫酸盐气溶胶层。这一新的PMC核来源解释了1991年火山爆发后PMC发生率的急剧下降。皮纳图博WACCM 3与微观物理将运行与火山输入，以更好地了解每个PMC变异的影响。这将是第一次对PMC进行三维微物理建模，具有交互动力学和化学，从而能够进一步研究自然和人为对云的影响。该项目更广泛的影响包括它将促进的网络和伙伴关系、广泛传播成果、公共宣传和对社会的好处。该项目将通过为研究生提供研究高层大气的机会来整合研究和教育。这项工作将是最近制定的计划的一部分，在该计划中，一些科学家和学生正在学习WACCM模型，以便与NCAR的科学家合作，将其应用于各种科学问题。将PMC微观物理学纳入WACCM 3将为高层大气研究界提供一种新的工具，使科学家能够更准确地测试有关PMC形成和演变的理论，解释观测结果，并了解中间层变化和与低海拔的耦合。将开发网站，以描述目前对PMC和全球变化的理解，针对学生和公众。