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Title: The role of conditional symmetric instability in numerical weather prediction
Author: Glinton, Michael
Awarding Body: University of Reading
Current Institution: University of Reading
Date of Award: 2013
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The release of conditional symmetric instability (CSI; a type of moist symmetric instability), which yields slantwise convection, has been associated with mesoscale atmospheric phenomena such as frontal precipitation bands, cloud heads in rapidly developing extratropical cyclones and sting jets. A number of case studies of CSI have been previously published, but the climatological role of CSI release is not well understood. Slantwise convection is not parameterized in operational global-scale weather and climate models, but the justification for omitting this process has not been established. Towards answering these grand research questions, the aim of this thesis is to quantify the climatological role of CSI release, and link this to surface weather conditions. In Chapter 4, two contrasting extra-tropical cyclone case studies are examined to find the strengths and weaknesses of the following diagnostics for measuring CSI and its upright counterpart, conditional instability, and their release: convective available potential energy (CAPE), slantwise convective available potential energy (SCAPE), the vertical extent of upright instability (VRU) and the vertical extent of slantwise instability (VRS). An example of CSI release is studied. The climatologies of these diagnostics applied to the ERA-Interim reanalysis dataset are presented in Chapter 5. In Chapter 6, SCAPE and CAPE are correlated with observed and simulated precipitation at various spatial and temporal averaging. It is shown that CSI release is associated with extra-tropical cyclones, particularly enhancing precipitation. The different CSI diagnostics used in this study (VRS and SCAPE) depict the overall importance of CSI in a similar way, but differences in both case study and climatology should be noted.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available