CAREER: A Study of the Radiative Effects of Cloud Shadows on the Dynamics of Long-Lived Convective Storms

职业：云影对长寿命对流风暴动力学的辐射效应研究

• 批准号: 0644533
• 负责人: Paul Markowski
• 金额: $ 74.76万
• 依托单位: Pennsylvania State Univ University Park
• 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: 2007-05-01 至 2014-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0644533&HistoricalAwards=false
• 关键词: CAREER; Study; Radiative; Effects; Cloud

Under this CAREER award, the Principal Investigator will investigate the radiative effects of cirrus anvils and their shadows on the dynamics of long-lived convective storms. The dynamical impacts will be examined using an advanced, research, three-dimensional cloud model with ice physics and radiation, in addition to a soil model and surface fluxes, which couple the radiative forcing at the surface to the overlying storm inflow within the boundary layer.The educational component is two-fold: (1) development of a suite of interactive numerical models for use in a variety of courses for undergraduate and graduate students; (2) creation of an interactive museum exhibit that showcases atmospheric research on severe storms and fully immerses visitors in the discovery process that defines science. Intellectual Merit: Despite significant advances in computing power, radiative effects generally have been ignored in past three-dimensional numerical modeling studies of the dynamics of convective storms. The exclusion often has been justified on the assumption that radiative effects are unimportant on the time scales that convection typically persists, and using the argument that convection is "dynamically " rather than "radiatively driven." Even though the above arguments are true for many storms, significant low-level cooling (e.g., temperature deficits exceeding 5 K) is occasionally observed beneath the expansive anvils of long-lived convective storms. Idealized numerical simulations that have represented this effect in a crude manner strongly suggest that a potentially important forcing is being missed when such substantial low-level temperature modifications are not captured. Scale analysis indicates that the temperature gradients associated with anvil shadows can be large enough to generate significant baroclinic horizontal vorticity, which can be converted to vertical vorticity, and hence storm rotation, through tilting by an updraft. On the other hand, cooling beneath the optically-thick cloud of a convective storm reduces convective available potential energy and increases the convective inhibition. The proposed research will investigate the effects-which quite possibly compete with one another-of radiatively-induced storm inflow modifications, e.g., baroclinic horizontal vorticity generation, stability modifications, etc. Specifically, the research will address the following questions: . What are the possible dynamical effects on convective storms from radiative transfer processes associated with anvils? . What are the magnitudes of these dynamical effects? . On what time scales are the radiative effects important? . Under which environmental conditions (e.g., sounding and hodograph characteristics, surface characteristics, time of day) do radiative effects exert the largest influence on convective storm evolution? Broader Impacts: The research has ramifications in a potentially broad range of areas, such as (i) warm season precipitation forecasting; (ii) the representation of cloud radiative transfer processes in large-scale models; and (iii) the development or intensification of rotation within severe storms, which are sensitive to variations in horizontal vorticity present in the inflow. The suite of simple, web-based numerical models in the educational component will augment students' classroom instruction by way of simulation-based laboratory exercises designed to promote creativity and critical thinking. Such exercises will have the utmost flexibility, allowing students to formulate and test their own hypotheses and perhaps even expose areas ripe for future rigorous scientific research. The atmospheric sciences museum exhibit will provide a highly interactive, "hands on" learning experience to a target audience that ranges from elementary school to adult.

根据这项职业奖，首席研究员将研究卷云砧及其阴影对长寿命对流风暴动力学的辐射影响。 除了土壤模型和地表通量外，还将使用一个先进的、研究性的、带有冰物理学和辐射的三维云模型来检查动力学影响，该模型将地表的辐射强迫与边界层内的上覆风暴流入耦合起来。（1）开发一套交互式数值模型，用于本科生和研究生的各种课程;（2）创建一个互动的博物馆展览，展示对严重风暴的大气研究，并使游客完全沉浸在定义科学的发现过程中。智力优势：尽管在计算能力上有了显著的进步，但在过去的对流风暴动力学的三维数值模拟研究中，辐射效应通常被忽略。 这种排除通常是合理的假设，即辐射效应在对流持续存在的时间尺度上是不重要的，并使用对流是“动态”而不是“辐射驱动”的论点。“尽管上述论点对许多风暴都是正确的，但显著的低空冷却（例如，温度赤字超过5 K），偶尔会观察到下长寿命对流风暴的膨胀砧。 理想化的数值模拟，代表了这种效果，在一个粗略的方式强烈建议，一个潜在的重要强迫被错过时，这种实质性的低层温度的修改没有被捕获。 尺度分析表明，与砧影相关的温度梯度可以足够大，以产生显着的斜压水平涡度，这可以转换为垂直涡度，因此风暴旋转，通过倾斜的上升气流。 另一方面，在对流风暴的光学厚云下的冷却减少了对流可用位能，并增加了对流抑制。 拟议的研究将调查辐射引起的风暴流入量修改的影响-很可能相互竞争，例如，斜压水平涡度生成、稳定性修正等。具体而言，研究将解决以下问题：与铁砧有关的辐射传输过程对对流风暴可能有什么动力学影响？.这些动力学效应的大小是多少？.在什么时间尺度上辐射效应是重要的？.在何种环境条件下（例如，探空和速矢线特征、地面特征、一天中的时间）辐射效应对对流风暴演变的影响最大吗？更广泛的影响：这项研究在一系列潜在的领域产生了影响，例如：（一）暖季降水预报;（二）大尺度模式中云辐射传输过程的表示;以及（三）严重风暴内旋转的发展或加强，这对流入中水平涡度的变化很敏感。教育部分中的一套简单的基于网络的数值模型将通过旨在促进创造力和批判性思维的基于模拟的实验室练习来增强学生的课堂教学。 这种练习将具有最大的灵活性，允许学生制定和测试自己的假设，甚至可能揭示未来严格的科学研究成熟的领域。 大气科学博物馆展览将为从小学到成人的目标受众提供高度互动的“动手”学习体验。