| 项目编号: | 1561996
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| 项目名称: | Effects of Turbulent Dissipation and Pressure Perturbations on Clouds |
| 作者: | Vincent Larson
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| 承担单位: | University of Wisconsin-Milwaukee
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| 批准年: | 2016
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| 开始日期: | 2016-06-15
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| 结束日期: | 2019-05-31
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| 资助金额: | 235135
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| 资助来源: | US-NSF
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| 项目类别: | Continuing grant
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| 国家: | US
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| 语种: | 英语
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| 特色学科分类: | Geosciences - Atmospheric and Geospace Sciences
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| 英文关键词: | cloud case
; cloud field
; turbulent dissipation
; pressure effect
; dissipation rate
; profound effect
; cumulus cloud
; pressure process
; large-scale emergent cloud property
; pressure covariance
; turbulent scalar dissipation
; non-hydrostatic pressure perturbation
; pressure-related behavior
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| 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. |
| 资源类型: | 项目
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| 标识符: | http://119.78.100.158/handle/2HF3EXSE/92068
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| Appears in Collections: | 全球变化的国际研究计划
科学计划与规划
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| Recommended Citation: | |
Vincent Larson. Effects of Turbulent Dissipation and Pressure Perturbations on Clouds. 2016-01-01.
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