Effects of Turbulent Dissipation and Pressure Perturbations on Clouds

GSTDTAP

项目编号	1561996
	Effects of Turbulent Dissipation and Pressure Perturbations on Clouds
	Vincent Larson
主持机构	University of Wisconsin-Milwaukee
项目开始年	2016
	2016-06-15
项目结束日期	2019-05-31
资助机构	US-NSF
项目类别	Continuing grant
项目经费	235135(USD)
国家	美国
语种	英语
英文摘要	Turbulent dissipation and non-hydrostatic pressure perturbations have profound effects on the structure and evolution of cloud fields. For example, turbulent mixing of dry environmental air into cumulus clouds may greatly reduce their buoyancy and moisture content. Viewing this process as a problem in entrainment has led to controversy in part because entrainment is difficult to define in a precise and practically useful way. Instead, it may help to focus attention on the turbulent scalar dissipation of, e.g., total water content, which has a mathematical definition and appears explicitly in the equation for the variance of total water. To cite another example, wind fields are highly anisotropic in stratocumulus layers just below the inversion, with the static stability above suppressing vertical motion but not horizontal motion. Intellectual Merit: Study of these phenomena has been impeded in part by the difficulty of making observational measurements. Recently, however, two new opportunities have arisen. First, new and useful diagnostics are becoming available in large-eddy simulation (LES) models that have simulated a variety of cloud cases. In particular, budgets of velocity and scalar variances are becoming available, along with estimates of dissipation rate. Second, higher-order closure parameterizations that can take advantage of improved understanding of turbulence and pressure effects have now been implemented in weather forecast and climate models. This enables the possibility of exploring how small-scale turbulent processes influence large-scale emergent cloud properties. To explore turbulent and pressure processes in cloud fields, several steps will be undertaken. First, additional budgets and diagnostics will be implemented in a LES model. Second, LES of cloud cases will be analyzed in order to better understand the turbulent and pressure-related behaviors. Third, the LES output will be used to evaluate existing and new parameterizations of turbulent dissipation and pressure covariances. Finally, regional and global simulations with various parameterizations will be performed in order to better understand how different assumptions influence large-scale fields. Broader Impacts: The research group has been offering internships since 2007 to software engineering students at a local undergraduate institution. Those undergraduates see firsthand both the power and pitfalls of working with large pieces of software. In return, the students help the project to improve software development. Eleven undergraduates have completed the internships, and all have obtained good jobs in software. This program will be continued this student training. In addition, the project will train a graduate student, disseminate research broadly, and improve modeling techniques that may be of use in weather forecast and climate models.
URL	查看原文
文献类型	项目
条目标识符	http://119.78.100.173/C666/handle/2XK7JSWQ/69669
专题	环境与发展全球科技态势
推荐引用方式 GB/T 7714	Vincent Larson.Effects of Turbulent Dissipation and Pressure Perturbations on Clouds.2016.