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.

根据该职业生涯奖，首席调查员将调查卷卷弧菌及其阴影对长寿风暴动态的辐射影响。 除了土壤模型和表面通量外，还将使用高级，研究的三维云模型对动态影响进行检查，除了土壤模型和表面通量外，这将表面上的辐射强迫与边界层的上覆的风暴流入相结合。 （2）创建一个互动博物馆展出，该博物馆展示了关于严重风暴的大气研究，并完全沉浸在定义科学的发现过程中。智力优点：尽管计算能力取得了重大进展，但在过去对对流风暴动力学的三维数值模型研究中，辐射效应通常被忽略了。 排除通常是合理的，假设辐射效应在对流通常持续存在的时间尺度上并不重要，并且使用对流“动态”而不是“辐射驱动”的论点。 即使上述论点对于许多风暴都是正确的，但有时在长期存在的对流风暴的巨大砧室下观察到明显的低水平冷却（例如，温度赤字超过5 K）。 以粗略的方式代表了这种效果的理想化数值模拟强烈表明，当未捕获这种实质性的低水平温度修饰时，可能会遗漏潜在的重要强迫。 比例分析表明，与砧阴影相关的温度梯度可能足够大，可以产生明显的压力水平涡度，可以将其转换为垂直涡度，从而通过上升气流通过倾斜度来转换风暴旋转。 另一方面，在对流风暴的光学厚云下冷却可减少对流的势能，并增加对流抑制作用。 拟议的研究将调查效果 - 很可能会与彼得诱发的风暴流入修饰，例如斜射水平涡度产生，稳定性修饰等竞争。具体而言，该研究将解决以下问题：。与砧座相关的辐射转移过程对对流风暴的可能动态影响是什么？ 。这些动态效应的幅度是多少？ 。在什么时间尺度上，辐射效应很重要？ 。在哪些环境条件下（例如，响声和大节摄影特征，表面特征，一天中的时间）辐射效应对对流风暴的演变产生最大的影响？更广泛的影响：该研究在潜在广泛的领域中产生了影响，例如（i）温暖的季节降水预测； （ii）大规模模型中云辐射转移过程的表示； （iii）严重风暴中旋转的发展或强化，这对流入中存在的水平涡度变化敏感。教育组成部分中简单的基于网络的数值模型的套件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。 这样的练习将具有最大的灵活性，使学生能够提出和测试自己的假设，甚至可能使领域成熟，以便将来进行严格的科学研究。 大气科学博物馆的展览将为目标受众提供高度互动的“手”学习体验，从小学到成人。