國立虎尾科技大學 |

Advancing Climate Understanding Through Idealized Models of Moist Atmospheric Convection.

Record Type:	Language materials, manuscript : Monograph/item
Title/Author:	Advancing Climate Understanding Through Idealized Models of Moist Atmospheric Convection./
Author:	Chien, Mu-Hua.
Description:	1 online resource (156 pages)
Notes:	Source: Dissertations Abstracts International, Volume: 85-08, Section: B.
Contained By:	Dissertations Abstracts International85-08B.
Subject:	Atmospheric sciences. -
Online resource:	click for full text (PQDT)
ISBN:	9798381741209

Advancing Climate Understanding Through Idealized Models of Moist Atmospheric Convection.
Chien, Mu-Hua.

Advancing Climate Understanding Through Idealized Models of Moist Atmospheric Convection. - 1 online resource (156 pages)

Source: Dissertations Abstracts International, Volume: 85-08, Section: B.

Thesis (Ph.D.)--New York University, 2024.

Includes bibliographical references

This thesis investigates the emergence and sensitivity of hurricane-like vortices in idealized simulations in conditionally unstable atmosphere. This idealized setting applies a rotating Business atmosphere with simplified thermodynamics for phase transitions. The conditionally unstable environment is enforced by prescribing the temperature and humidity at the upper and lower boundaries, and a prescribed radiative cooling is applied to the simplified configuration. The governing equations are solved numerically using a variable-density incompressible Navier-Stokes solver as a direct numerical simulation. This idealized configuration is sufficient to resolve the characteristics of moist convection. In this thesis, we explore how hurricane-like vortices respond to variations in rotation rate and the introduction of radiative cooling, particularly in the context of climate change scenarios.Rotation influences the equilibrium state, causing self-aggregated convection to organize into hurricane-like vortices. These vortices exhibit features reminiscent of Earth's tropical cyclones, the warm core where humid air rises, leading to an eyewall formation. The conditions prompting the emergence of these vortices, such as sea surface temperature and the rate of rotation, align with those observed in Earth's tropical region. This experiment omits interactions with radiation, wind-evaporation feedback, or cloud microphysics. Although such processes might be relevant to Earth's tropical cyclone development, our results emphasize the role of atmospheric dynamics combined with rotation and phase transitions in the formation and maintenance of these hurricane-like vortices. Radiative cooling destabilizes the lower atmospheric layer, consequently enhancing upward mass and heat transport. This destabilization with sufficient cooling triggers local instability and lead to a transition in the equilibrium regime where structured hurricane-like vortices are replaced by disorganized convective plumes. Additionally, radiative cooling increases the kinetic energy generation performed by the hurricane-like vortices, associated with the increased vertical transport of total water content. Despite an increase in kinetic energy generation in the presence of radiative cooling, mechanical efficiency-defined as the ratio of kinetic energy generation rate to available potential energy generation rate-experiences a reduction. This reduction is linked to increased mixing throughout the domain, associated with the destabilization at the lower boundary. We observe a deceleration in the isentropic overturning circulation, which is determined by sorting air parcels based on their moist entropy, when there's a reduction in the radiative cooling rate. This change is particularly associated with rises in surface temperature. Using an idealized framework, we model hurricane-like vortices as traditional heat engines acting in order to evaluate how much energy it contains and how much work it can do. In the context of global warming, our findings indicate that the mechanical efficiency of these hurricane-like vortices, when viewed as heat engines, increases. This is observed even as there is a decline in both the mass flux and energy flux. A deeper analysis reveals that, in a warmer climate, hurricane-like vortices exhibit a more structured form. This enhanced structure helps prevent the vortex core from external dry air mixing, enabling it to maintain its efficiency.

Electronic reproduction.
Ann Arbor, Mich. :
ProQuest,
2024

Mode of access: World Wide Web

ISBN: 9798381741209Subjects--Topical Terms:

1179392
Atmospheric sciences.
Subjects--Index Terms:

Isentropic analysisIndex Terms--Genre/Form:

554714
Electronic books.

Advancing Climate Understanding Through Idealized Models of Moist Atmospheric Convection.
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504 $a Includes bibliographical references
520 $a This thesis investigates the emergence and sensitivity of hurricane-like vortices in idealized simulations in conditionally unstable atmosphere. This idealized setting applies a rotating Business atmosphere with simplified thermodynamics for phase transitions. The conditionally unstable environment is enforced by prescribing the temperature and humidity at the upper and lower boundaries, and a prescribed radiative cooling is applied to the simplified configuration. The governing equations are solved numerically using a variable-density incompressible Navier-Stokes solver as a direct numerical simulation. This idealized configuration is sufficient to resolve the characteristics of moist convection. In this thesis, we explore how hurricane-like vortices respond to variations in rotation rate and the introduction of radiative cooling, particularly in the context of climate change scenarios.Rotation influences the equilibrium state, causing self-aggregated convection to organize into hurricane-like vortices. These vortices exhibit features reminiscent of Earth's tropical cyclones, the warm core where humid air rises, leading to an eyewall formation. The conditions prompting the emergence of these vortices, such as sea surface temperature and the rate of rotation, align with those observed in Earth's tropical region. This experiment omits interactions with radiation, wind-evaporation feedback, or cloud microphysics. Although such processes might be relevant to Earth's tropical cyclone development, our results emphasize the role of atmospheric dynamics combined with rotation and phase transitions in the formation and maintenance of these hurricane-like vortices. Radiative cooling destabilizes the lower atmospheric layer, consequently enhancing upward mass and heat transport. This destabilization with sufficient cooling triggers local instability and lead to a transition in the equilibrium regime where structured hurricane-like vortices are replaced by disorganized convective plumes. Additionally, radiative cooling increases the kinetic energy generation performed by the hurricane-like vortices, associated with the increased vertical transport of total water content. Despite an increase in kinetic energy generation in the presence of radiative cooling, mechanical efficiency-defined as the ratio of kinetic energy generation rate to available potential energy generation rate-experiences a reduction. This reduction is linked to increased mixing throughout the domain, associated with the destabilization at the lower boundary. We observe a deceleration in the isentropic overturning circulation, which is determined by sorting air parcels based on their moist entropy, when there's a reduction in the radiative cooling rate. This change is particularly associated with rises in surface temperature. Using an idealized framework, we model hurricane-like vortices as traditional heat engines acting in order to evaluate how much energy it contains and how much work it can do. In the context of global warming, our findings indicate that the mechanical efficiency of these hurricane-like vortices, when viewed as heat engines, increases. This is observed even as there is a decline in both the mass flux and energy flux. A deeper analysis reveals that, in a warmer climate, hurricane-like vortices exhibit a more structured form. This enhanced structure helps prevent the vortex core from external dry air mixing, enabling it to maintain its efficiency.
533 $a Electronic reproduction. $b Ann Arbor, Mich. : $c ProQuest, $d 2024
538 $a Mode of access: World Wide Web
650 4 $a Atmospheric sciences. $3 1179392
650 4 $a Fluid mechanics. $3 555551
650 4 $a Climate change. $2 bicssc $3 1009004
653 $a Isentropic analysis
653 $a Moist convection
653 $a Tropical cyclone
653 $a Atmospheric dynamics
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