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Articles 1 - 8 of 8
Full-Text Articles in Physical Sciences and Mathematics
On The Structure And Phase Speeds Of The Kelvin Waves And Mjo Over The Indian Ocean, Ahmed Shaaban
On The Structure And Phase Speeds Of The Kelvin Waves And Mjo Over The Indian Ocean, Ahmed Shaaban
Legacy Theses & Dissertations (2009 - 2024)
Kelvin waves in the stratosphere are well known to behave as radiative gravity waves. Yet, the tropospheric component of these Kelvin waves (and other tropical modes) has often been described as superpositions between the baroclinic modes. By decomposing the Kelvin waves into upward and downward-phase components, we found that only upward-phase Kelvin waves occupy the troposphere, indicating that the tropospheric Kelvin waves are not vertical standing oscillations as previously thought. Fast Kelvin waves were found to obey the structure of radiating gravity waves, like their stratospheric counterpart, more than the moist waves. The unexpected lack of variation in vertical tilt …
An Examination Of The Arctic Environment And Arctic Cyclones During Periods Of Low And High Forecast Skill Of The Synoptic-Scale Flow, Kevin Biernat
An Examination Of The Arctic Environment And Arctic Cyclones During Periods Of Low And High Forecast Skill Of The Synoptic-Scale Flow, Kevin Biernat
Legacy Theses & Dissertations (2009 - 2024)
This dissertation compares Arctic environmental conditions and Arctic cyclones (ACs) between periods of low and high forecast skill of the synoptic-scale flow over the Arctic during summer, hereafter referred to as low-skill periods and high-skill periods, respectively. This dissertation also examines features and processes influencing the evolution and forecast skill of selected categories of ACs.
Global Circulation Variability Associated With Mjo Phase Speed, Alexander Marat Tomoff
Global Circulation Variability Associated With Mjo Phase Speed, Alexander Marat Tomoff
Legacy Theses & Dissertations (2009 - 2024)
Differences in the Madden–Julian oscillation (MJO) phase speed help explain some of the variability in the global circulation patterns associated with the MJO. Select mechanisms that identify these distinctive circulation signals are applied to help explain MJO variability associated with different phase speeds. Wavelet filter analysis is first used to compute regression models of the MJO at different phase speeds, isolating the associated patterns in outgoing longwave radiation (OLR), geopotential height, and upper-level wind. Covariance matrices provide a deeper understanding of how the tropical and extratropical patterns compare between two phase speeds at any point in time. Both Fourier and …
The Significance Of The Nontraditional Coriolis Terms In Tropical Large-Scale Dynamics, Heng Wang
The Significance Of The Nontraditional Coriolis Terms In Tropical Large-Scale Dynamics, Heng Wang
Legacy Theses & Dissertations (2009 - 2024)
The nontraditional Coriolis terms (NCTs) turn eastward motion upward and upward motion westward, and vice versa. NCTs are omitted in most of the current global atmospheric models. However, NCTs are significant in tropical large-scale dynamics in at least three aspects. 1) Using an idealized model that can switch NCTs on or off, omitting NCTs biases large-scale flow response to prescribed diabatic forcing mimicking the intertropical convergence zone (ITCZ). The omission yields a westerly wind bias in the heating region ~ 10% of the westerly jet stream. This bias is due to lack of westward NCT when heating-induced upward motion is …
Stratospheric And Tropospheric Contributions To The Poleward Energy Flux Across 70°N And 65°S In The Merra-2 And Cesm, Christopher Cardinale
Stratospheric And Tropospheric Contributions To The Poleward Energy Flux Across 70°N And 65°S In The Merra-2 And Cesm, Christopher Cardinale
Legacy Theses & Dissertations (2009 - 2024)
The flux of moist static energy (MSE) across 70°N and 65°S plays a key role in the energy budget and climate of the polar regions. This flux, which provides respectively 98 W m⁻² and 91 W m⁻² heating of the northern and southern polar caps, is usually studied from a vertically integrated perspective. Its vertical structure is examined using the NASA-MERRA-2 reanalysis to compute monthly fluxes of sensible, latent and potential energy across 70°N and 65°S for the period 1980-2016. The flux is bimodal, with peaks in the lower troposphere and in the middle stratosphere, and is near zero at …
The Relationship Between Tropospheric Synoptic-Scale Events, Vertical Wave Activity Flux, And Sudden Stratospheric Warmings In The Boreal Winter, Hannah Elizabeth Attard
The Relationship Between Tropospheric Synoptic-Scale Events, Vertical Wave Activity Flux, And Sudden Stratospheric Warmings In The Boreal Winter, Hannah Elizabeth Attard
Legacy Theses & Dissertations (2009 - 2024)
Rapid breakdowns of the climatological mid-winter stratospheric polar vortex [i.e., sudden stratospheric warmings (SSWs)] are often preceded by tropospheric blocks. While some studies suggest that blocks can induce the upward wave activity flux (WAF) through the tropopause region that is necessary to trigger an SSW, other studies show no statistical relationship between tropospheric blocks and SSWs. One objective of this dissertation is to elucidate the dynamical relationship between tropospheric blocks and SSWs by exploring the relationship between blocks and tropopause-level upward WAF. Along with analyzing blocks, this dissertation also explores rapidly deepening extratropical cyclones (i.e., bombs) and tropical cyclones that …
Variations In Potential Vorticity Streamer Activity : Development Pathways, Environmental Impacts, And Links To Tropical Cyclone Activity In The North Atlantic Basin, Philippe Pierre Papin
Variations In Potential Vorticity Streamer Activity : Development Pathways, Environmental Impacts, And Links To Tropical Cyclone Activity In The North Atlantic Basin, Philippe Pierre Papin
Legacy Theses & Dissertations (2009 - 2024)
This dissertation examines the climatological occurrence of potential vorticity streamers (PVSs) during the tropical cyclone (TC) season that occur in the upper troposphere in the North Atlantic (NATL) basin, assessing how their variations in frequency, area, and intensity impact the synoptic environment, how they are induced by different synoptic-dynamic patterns, and how they modify TC activity and genesis pathways.
Upper-Tropospheric Precursors Associated With Subtropical Cyclone Formation In The North Atlantic Basin, Alicia Marie Bentley
Upper-Tropospheric Precursors Associated With Subtropical Cyclone Formation In The North Atlantic Basin, Alicia Marie Bentley
Legacy Theses & Dissertations (2009 - 2024)
Oceanic cyclones exhibiting properties of both tropical and extratropical systems have been categorized as subtropical cyclones (STCs) since the early 1950s. The opportunity to investigate the roles of baroclinic and diabatic processes during the evolution of STCs from a potential vorticity (PV) perspective motivates this study. This study investigates the roles of baroclinic and diabatic processes during the evolution of STCs by calculating three PV metrics from the National Centers for Environmental Prediction Climate Forecast System Reanalysis 0.5° gridded dataset. The three PV metrics quantify the relative contributions of lower-tropospheric baroclinic processes, midtropospheric diabatic heating, and upper-tropospheric dynamical processes during …