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Ice versus Liquid Water Saturation in Regional Climate Simulations of the Indian Summer Monsoon

Title: Ice versus Liquid Water Saturation in Regional Climate Simulations of the Indian Summer Monsoon.
Name(s): Glazer, Russell Henderson, author
Misra, Vasubandhu, 1970-, professor directing dissertation
Shanbhag, Sachin, university representative
Bourassa, Mark Allan, committee member
Hart, Robert E., 1972-, committee member
Liu, Guosheng, (Professor of meteorology), committee member
Florida State University, degree granting institution
College of Arts and Sciences, degree granting college
Department of Earth, Ocean and Atmospheric Science, degree granting department
Type of Resource: text
Genre: Text
Doctoral Thesis
Issuance: monographic
Date Issued: 2018
Publisher: Florida State University
Place of Publication: Tallahassee, Florida
Physical Form: computer
online resource
Extent: 1 online resource (135 pages)
Language(s): English
Abstract/Description: At the same temperature, below 0oC, the saturation vapor pressure (SVP) over ice is slightly less than the SVP over liquid water. Numerical models use the Clausius-Clapeyron relation to calculate the SVP and relative humidity, but there is not a consistent method for the treatment of saturation above the freezing level where ice and mixed-phase clouds may be present. In the context of current challenges presented by cloud microphysics in climate models, we argue that a better understanding of the impact that this treatment has on saturation-related processes like cloud formation and precipitation, is needed. This study explores the importance of the SVP calculation through model simulations of the Indian Summer Monsoon (ISM) using atmosphere-only simulations with the Regional Spectral Model (RSM) and RSM coupled to the Regional Ocean Modeling System (RSM-ROMS). Atmosphere-only simulations are conducted with two saturation parameterizations. In one, the SVP over liquid water is prescribed through the entire atmospheric column (woIce), and in another the SVP over ice is used above the freezing level (wIce). When SVP over ice is prescribed, a thermodynamic drying of the middle and upper troposphere above the freezing level occurs due to increased condensation. In the wIce runs, the model responds to the slight decrease in the saturation condition by increasing, relative to the SVP over liquid water only run, grid-scale condensation of water. Changes in the cloud layer amounts in the wIce simulation cause in increase in the net heat flux (NHF) at the surface of 2-3 W/m2 over the Arabian Sea (AS) and a decrease of similar magnitude over the eastern equatorial Indian Ocean (EEIO). Motivated by these NHF changes the wIce and woIce experiments were repeated in the coupled simulations. With coupling added, the ocean is allowed to respond to any NHF changes; however we find that the NHF difference between wIce-woIce over the AS is near zero. It is proposed that with the inclusion of air-sea coupling the atmospheric and oceanic response to changes in the SVP is damped relative to the forced RSM integrations. The importance of air-sea interaction for the northward propagation and evolution of the Indian monsoon intrareasonal oscillation (ISO) is examined through a comparison between the uncoupled and coupled simulations, and the observed ISO. It was found that the observed ISO contains a robust air-sea interaction during its evolution which would suggest that coupling is required to simulate the observed relationship between the ocean and atmosphere during the ISO. However, the uncoupled simulations show the ability to simulate realistic amplitude ISOs without coupling to the ocean, suggesting that there is an internal atmospheric component that is important for simulating the observed ISO period and amplitude.
Identifier: 2018_Sp_Glazer_fsu_0071E_14515 (IID)
Submitted Note: A Dissertation submitted to the Department of Earth, Ocean and Atmospheric Science in partial fulfillment of the requirements for the degree of Doctor of Philosophy.
Degree Awarded: Spring Semester 2018.
Date of Defense: April 9, 2018.
Keywords: Boreal Summer Intraseasonal Oscillation, Cloud Scheme, Indian Monsoon, Saturation Vapor Pressure
Bibliography Note: Includes bibliographical references.
Advisory Committee: Vasubandhu Misra, Professor Directing Dissertation; Sachin Shanbhag, University Representative; Mark Bourassa, Committee Member; Robert Hart, Committee Member; Guosheng Liu, Committee Member.
Subject(s): Meteorology
Persistent Link to This Record:
Host Institution: FSU

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Glazer, R. H. (2018). Ice versus Liquid Water Saturation in Regional Climate Simulations of the Indian Summer Monsoon. Retrieved from