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Articles 1 - 6 of 6
Full-Text Articles in Physical Sciences and Mathematics
Predictability Of African Easterly Waves In An Operational Ensemble Prediction System, Travis J. Elless
Predictability Of African Easterly Waves In An Operational Ensemble Prediction System, Travis J. Elless
Legacy Theses & Dissertations (2009 - 2024)
African easterly waves (AEWs) are the primary synoptic-scale weather feature found in sub-Saharan Africa during boreal summer. Many studies have used observations and idealized models to highlight processes associated with the movement and growth of AEWs, yet there have been few studies documenting the performance of operational ensemble prediction systems (EPSs) for these phenomena. Here, the predictability of AEWs in ECMWF EPS forecasts is assessed during two periods of enhanced AEW activity (July--September 2007--2009 and 2011--2013). Specifically, AEW predictability is analyzed through three main areas of focus: 1) verifying AEW position and intensity forecasts, and assessing their relation to convective …
Tropical Cyclone Rapid Intensification In Environments Of Upper-Tropospheric Troughs : Environmental Influences And Convective Characteristics, Michael Fischer
Tropical Cyclone Rapid Intensification In Environments Of Upper-Tropospheric Troughs : Environmental Influences And Convective Characteristics, Michael Fischer
Legacy Theses & Dissertations (2009 - 2024)
Intensity forecasts for tropical cyclones that undergo a period of rapid intensification are particularly susceptible to large errors. For those storms that interact with an upper-tropospheric trough, tropical cyclone intensity forecasts are complicated, as upper-tropospheric troughs can provide unique intensification mechanisms, but are often associated with unfavorable environmental conditions. Although tropical cyclones in environments with nearby upper-tropospheric troughs are associated with lesser intensification rates than tropical cyclones in environments devoid of upper-tropospheric troughs, some tropical cyclone--trough interactions are associated with a period of rapid intensification. This dissertation utilizes reanalysis output, satellite observations, and ensemble modeling simulations to understand whether rapid …
What Affects The Phase Speed Of Madden-Julian Oscillation Convection, Robert Setzenfand
What Affects The Phase Speed Of Madden-Julian Oscillation Convection, Robert Setzenfand
Legacy Theses & Dissertations (2009 - 2024)
The Madden-Julian Oscillation (MJO) is the main source of convective and circulation variability on intraseasonal timescales and planetary spatial scales within the tropics. Although the phase speed of the MJO convective envelope is often stated as 5 m s–1, MJO events that occur over the Indo-Pacific warm pool can have a range of phase speeds. This study uses a wavelet to identify MJO convective events with specified phase speeds in a satellite-derived outgoing longwave radiation (OLR) dataset during boreal winter. The wavelet-filtered OLR index is then regressed against basic meteorological variables to extract information about MJO events or signals propagating …
Influence Of Lightning-Producing Convection On Tropical Cyclone Intensity Change, Stephanie Stevenson
Influence Of Lightning-Producing Convection On Tropical Cyclone Intensity Change, Stephanie Stevenson
Legacy Theses & Dissertations (2009 - 2024)
Lightning observations in tropical cyclones (TCs) over the ocean are a recent advance- ment, and while many studies have noted relationships between lightning and TC intensity change, the relationships are not consistent. This dissertation aims to understand the com- plexities of the relationships between lightning and TC intensity change, and associate the relationships to storm kinematic, thermodynamic, and microphysical processes.
Dry Air, Midlevel Flow, And The Persistence Of Deep Convection In Atlantic Tropical Disturbances, Charles Helms
Dry Air, Midlevel Flow, And The Persistence Of Deep Convection In Atlantic Tropical Disturbances, Charles Helms
Legacy Theses & Dissertations (2009 - 2024)
An analysis of dropsonde-observed relative humidity in the Tropical Storm Gabrielle (2013) pregenesis disturbance suggests the presence of a layer of dry air that is being advected into the disturbance from the north. The focus of this study is on this and similar dry air layers, termed dry air inflow pathways (DAIPs), that are characterized by unidirectional disturbance-relative flow drawing dry air into a tropical disturbance. It is hypothesized that DAIPs act to prevent the establishment of persistent deep convection by importing midlevel
Global Response To The Madden-Julian Oscillation As A Function Of Phase Speed In Era-Interim Reanalysis And Miroc5 Model Data, Kaitlyn Krzyzaniak
Global Response To The Madden-Julian Oscillation As A Function Of Phase Speed In Era-Interim Reanalysis And Miroc5 Model Data, Kaitlyn Krzyzaniak
Legacy Theses & Dissertations (2009 - 2024)
Many authors state that the phase speed of the Madden–Julian oscillation (MJO) is near 5ms–1, but observations suggest it varies considerably. MJO propagation typically sets off Rossby wave trains that interact with and alter this extratropical pattern; however, differences in the MJO phase speed could alter the Rossby wave response, leading to a unique response in the extratropics. An understanding of the mechanisms and extratropical responses to variable MJO phase speeds would provide innovative and invaluable insight for subseasonal forecasting.