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A study of the diurnal cycle of mois...

Wu, Chien-Ming.

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A study of the diurnal cycle of moist convection over land using a cloud -system resolving model.

Record Type:	Electronic resources : Monograph/item
Title/Author:	A study of the diurnal cycle of moist convection over land using a cloud -system resolving model./
Author:	Wu, Chien-Ming.
Published:	Ann Arbor : ProQuest Dissertations & Theses, : 2008,
Description:	112 p.
Notes:	Source: Dissertations Abstracts International, Volume: 70-11, Section: B.
Contained By:	Dissertations Abstracts International70-11B.
Subject:	Atmospheric sciences. -
Online resource:	https://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3347017
ISBN:	9781109022216

A study of the diurnal cycle of moist convection over land using a cloud -system resolving model.
Wu, Chien-Ming.

A study of the diurnal cycle of moist convection over land using a cloud -system resolving model. - Ann Arbor : ProQuest Dissertations & Theses, 2008 - 112 p.

Source: Dissertations Abstracts International, Volume: 70-11, Section: B.

Thesis (Ph.D.)--University of California, Los Angeles, 2008.

This item must not be sold to any third party vendors.

In the first part of the dissertation, we investigated the large-scale impact of cloud-scale interactions using a 2D cloud-system resolving model (CSRM) whose physics consists of three major components: cloud microphysics, radiation and turbulence. Experiments we have performed with the CSRM can be classified into three groups: CONTROL, MI (Mean Input) and MO (Mean Output) experiments. In MI experiments, the input to a selected physics subroutine is horizontally averaged at each call over the entire domain of the CSRM. These experiments, therefore, eliminate the cloud-scale horizontal modulation of the process in question from the beginning. In MO experiments, on the other hand, all calculations are performed on the cloud scale, but the output from a selected physics subroutine is horizontally averaged. These experiments, therefore, eliminate the local effects of the process in question on other cloud-scale processes. These experiments not only confirm the importance of cloud-scale interactions but also suggest the existence of a problem in formulating the overall effects of physical processes on averaged fields. In the second part of the dissertation, we assess the control mechanism for the transition from shallow to deep convection with the CSRM. By comparing with a 3-D CSRM under conditions taken from the Large-scale Biosphere Atmosphere (in the Amazon) field study, we show that the 2-D CSRM reasonably represents the main features evident in previous 3-D simulations. To extract the essence of the transition from shallow to deep convection, we idealize the case based on observations to isolate two control parameters, the free troposphere stability and the relative humidity. The systematic dependence of the development of convection on the stability and the humidity show that the concept of a convective transition is a meaningful one. A transition time can be defined to evaluate the relationship of the transition time on the free tropospheric humidity and the development of cold pools. Both have been implicated in past studies as key controls on the transition between shallow and deep convection. Neither satisfactorily explains the transition time of our experiments. Instead we find that the evolution of CAPE within the shallow cumulus layer is the key; as the transition coincides with the time when the environment of the shallow cumulus layer becomes unstable to the average cloud properties.

ISBN: 9781109022216Subjects--Topical Terms:

3168354
Atmospheric sciences.
Subjects--Index Terms:

Cloud-scale interactions

A study of the diurnal cycle of moist convection over land using a cloud -system resolving model.
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245 1 0 $a A study of the diurnal cycle of moist convection over land using a cloud -system resolving model.
260 1 $a Ann Arbor : $b ProQuest Dissertations & Theses, $c 2008
300 $a 112 p.
500 $a Source: Dissertations Abstracts International, Volume: 70-11, Section: B.
500 $a Publisher info.: Dissertation/Thesis.
500 $a Advisor: Stevens, Bjorn.
502 $a Thesis (Ph.D.)--University of California, Los Angeles, 2008.
506 $a This item must not be sold to any third party vendors.
506 $a This item must not be added to any third party search indexes.
520 $a In the first part of the dissertation, we investigated the large-scale impact of cloud-scale interactions using a 2D cloud-system resolving model (CSRM) whose physics consists of three major components: cloud microphysics, radiation and turbulence. Experiments we have performed with the CSRM can be classified into three groups: CONTROL, MI (Mean Input) and MO (Mean Output) experiments. In MI experiments, the input to a selected physics subroutine is horizontally averaged at each call over the entire domain of the CSRM. These experiments, therefore, eliminate the cloud-scale horizontal modulation of the process in question from the beginning. In MO experiments, on the other hand, all calculations are performed on the cloud scale, but the output from a selected physics subroutine is horizontally averaged. These experiments, therefore, eliminate the local effects of the process in question on other cloud-scale processes. These experiments not only confirm the importance of cloud-scale interactions but also suggest the existence of a problem in formulating the overall effects of physical processes on averaged fields. In the second part of the dissertation, we assess the control mechanism for the transition from shallow to deep convection with the CSRM. By comparing with a 3-D CSRM under conditions taken from the Large-scale Biosphere Atmosphere (in the Amazon) field study, we show that the 2-D CSRM reasonably represents the main features evident in previous 3-D simulations. To extract the essence of the transition from shallow to deep convection, we idealize the case based on observations to isolate two control parameters, the free troposphere stability and the relative humidity. The systematic dependence of the development of convection on the stability and the humidity show that the concept of a convective transition is a meaningful one. A transition time can be defined to evaluate the relationship of the transition time on the free tropospheric humidity and the development of cold pools. Both have been implicated in past studies as key controls on the transition between shallow and deep convection. Neither satisfactorily explains the transition time of our experiments. Instead we find that the evolution of CAPE within the shallow cumulus layer is the key; as the transition coincides with the time when the environment of the shallow cumulus layer becomes unstable to the average cloud properties.
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653 $a Moist convection
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