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

根据该职业奖，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效应。动力学影响将使用一个先进的、具有冰物理和辐射的研究三维云模型，以及一个土壤模型和地表通量来检验，地表通量将地表的辐射强迫与边界层内的上覆风暴流入相结合。教育部分有两个方面：(1)开发一套用于本科生和研究生各种课程的交互式数值模型；(2)建立一个互动式博物馆展览，展示对强风暴的大气研究，让参观者完全沉浸在科学的发现过程中。智力优势：尽管计算能力有了很大的进步，但在过去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，假设辐射效应在对流通常持续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是正确的，但在长寿命的对流风暴的膨胀砧下偶尔会观察到显著的低层冷却（例如，温度赤字超过5 K）。以粗略的方式表示这种影响的理想化数值模拟强烈表明，如果没有捕捉到这种实质性的低层温度变化，就会错过一个潜在的重要强迫。尺度分析表明，与砧状阴影相关的温度梯度可以大到足以产生显著的斜压水平涡度，而斜压水平涡度可以通过上升气流的倾斜转化为垂直涡度，从而产生风暴旋转。另一方面，对流风暴光学厚度云下的冷却降低了对流可用势能，增加了对流抑制。拟议的研究将调查辐射引起的风暴流入改变的影响，这些影响很可能相互竞争，例如斜压水平涡度的产生，稳定性的改变等。具体而言，研究将解决以下问题：。与铁砧相关的辐射传输过程对对流风暴可能产生的动力学影响是什么？． 这些动力效应的大小是多少？． 在什么时间尺度上辐射影响是重要的？． 在哪种环境条件下（例如，探空和回波特征、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？更广泛的影响：该研究可能在广泛的领域产生影响，例如(1)暖季降水预报；（ii）大尺度模式中云辐射传输过程的表示；（iii）强风暴中旋转的发展或加强，这对流入中存在的水平涡度变化很敏感。这套简单的、基于网络的数字模型在教育部分将通过基于模拟的实验室练习来增强学生的课堂教学，旨在促进创造力和批判性思维。这样的练习将具有最大的灵活性，允许学生制定和测试他们自己的假设，甚至可能为未来严格的科学研究提供成熟的领域。大气科学博物馆的展览将为从小学到成人的目标观众提供一个高度互动的“动手”学习体验。

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.