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Articles 1 - 8 of 8
Full-Text Articles in Physical Sciences and Mathematics
A Mechanism For Upscale Growth Of Convection In The Complex Terrain Of The Northeast U.S, Brennan Joseph Stutsrim
A Mechanism For Upscale Growth Of Convection In The Complex Terrain Of The Northeast U.S, Brennan Joseph Stutsrim
Legacy Theses & Dissertations (2009 - 2024)
Upstate New York has a variety of complex terrain that can interact with the background flow to create mesoscale heterogeneities in the lower troposphere. The major valleys of Upstate New York, the Hudson and Mohawk Valleys, often have increased moisture content and stronger surface winds than the higher terrain surrounding them. These features can have a profound effect on the evolution of convective storms, especially in cases characterized by low-to-moderate shear, which tends to favor pulse-like or multicellular convection. Analysis of composite radar imagery has indicated that convective storms often change mode while descending from the Catskills Mountains into the …
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 …
Evaluating Large-Scale And Storm-Scale Characteristics Of Rapidly Intensifying And Slowly Intensifying Tropical Cyclones Using An Analog Approach, Jannetta C. Richardson
Evaluating Large-Scale And Storm-Scale Characteristics Of Rapidly Intensifying And Slowly Intensifying Tropical Cyclones Using An Analog Approach, Jannetta C. Richardson
Legacy Theses & Dissertations (2009 - 2024)
Tropical cyclone (TC) intensity change is modulated by a combination of large-scale and storm-scale processes. On the large-scale, several factors exhibit strong controls on TC rapid intensification (RI): the initial TC intensity, the environmental vertical wind shear (VWS), and the background thermodynamic environment, which determines the TC’s maximum potential intensity (MPI). Previous statistical studies comparing RI and non-RI TCs have shown that TCs undergoing RI tend to be embedded in environments of lower VWS, and have initial intensities that are farther from their MPIs. Although numerous statistical studies have compared the large-scale and storm-scale conditions of RI and non-RI TCs, …
Synergistic Effects Of Midlevel Dry Air And Vertical Wind Shear On Tropical Cyclone Development, Joshua James Alland
Synergistic Effects Of Midlevel Dry Air And Vertical Wind Shear On Tropical Cyclone Development, Joshua James Alland
Legacy Theses & Dissertations (2009 - 2024)
This dissertation seeks to better understand how midlevel moisture and vertical wind shear (VWS) modulate tropical cyclone (TC) development. The first component of this dissertation simplifies the objective by focusing solely on how midlevel moisture modulates TC development, utilizing an axisymmetric modeling framework. Results show that low-entropy midlevel air affects the upward vertical mass flux in these experiments through subsidence into the subcloud layer, which results in a longer recovery time before deep convection develops. This process, as well as descending motion closer to the inner core, limits the radial width of deep convection, reduces the area of upward motions, …
A Revised Technique For Measuring Vertical Velocity Using Dropsondes, Timothy Connor Nelson
A Revised Technique For Measuring Vertical Velocity Using Dropsondes, Timothy Connor Nelson
Legacy Theses & Dissertations (2009 - 2024)
The earliest iterations of dropsondes in the 1960's obtained vertical velocity by measuring the geometric fall speed of the dropsonde and the true airspeed (TAS) of the dropsonde from a pitot-static. The vertical velocity errors from this methodology were claimed to be ±1 m s-1. Subsequent dropsonde iterations used various forms of the drag force equation to obtain vertical velocity. The accuracy of these drag force-based measurements, however, are also quite large at ±1–2 m s-1. In this dissertation, an attempt is made to improve vertical velocity errors by revisiting and revising the pitot-static-derived TAS methodology on the eXpendable Digital …
Hurricane Bonnie (1998) : Maintaining Intensity During High Vertical Wind Shear And An Eyewall Replacement Cycle, Erin Dougherty
Hurricane Bonnie (1998) : Maintaining Intensity During High Vertical Wind Shear And An Eyewall Replacement Cycle, Erin Dougherty
Legacy Theses & Dissertations (2009 - 2024)
Hurricane Bonnie (1998) was an unusually resilient hurricane that maintained intensity in 12–16 ms-1 vertical wind shear and during an eyewall replacement cycle from 23 – 25 August. This remarkable behavior was examined using observations from flight-level data, microwave imagery, radar, and dropsondes over the two-day period. The symmetric and asymmetric aspects of Bonnie’s eyewall replacement cycle were documented and compared to eyewall replacement cycles in other hurricanes. Similar to other observed eyewall replacement cycles, Bonnie exhibited the development, strengthening, and dominance of a secondary eyewall while a primary eyewall decayed. However, Bonnie’s structure was highly asymmetric due to strong …
Tropical Cyclone Intensification Under Moderate Vertical Wind Shear, Rosimar Rios-Berrios
Tropical Cyclone Intensification Under Moderate Vertical Wind Shear, Rosimar Rios-Berrios
Legacy Theses & Dissertations (2009 - 2024)
Deep-layer (200–850 hPa) vertical wind shear is generally an inhibiting factor for tropical cyclone intensification. Multiple studies—ranging from case studies to climatological analyses—have consistently shown that the chances of tropical cyclone intensification decrease with increasing vertical wind shear magnitude. However, tropical cyclones can intensify under moderate shear—the range of shear magnitudes that are neither too weak to have negligible influence on intensity nor too strong to completely halt intensification. Intensity, track, and precipitation forecasts of tropical cyclones under moderate shear can be highly uncertain; therefore, explaining how tropical cyclones evolve under seemingly unfavorable conditions is an important step towards improved …
The Intensification Of Sheared Tropical Cyclones, Leon Nguyen
The Intensification Of Sheared Tropical Cyclones, Leon Nguyen
Legacy Theses & Dissertations (2009 - 2024)
Environmental vertical wind shear has been shown to have a generally detrimental impact on tropical cyclone (TC) intensity change. However, many cases of rapidly intensifying (RI) sheared TCs have been observed, and TCs in moderate (5-10 m s-1) shear often have the largest intensity forecast errors. Thus, advancing the understanding of TC-shear interactions is vital to improving TC intensity forecasts, which have not seen much improvement over the past few decades. This dissertation employs both observational and high-resolution numerical modeling approaches to investigate how some TCs are able to resist shear and intensify.