{"id":{"repo_id":"tamu","oai_identifier":"oai:oaktrust.library.tamu.edu:1969.1/158140"},"canonical_url":"https://search.dev.ndltd.org/etd/tamu/oai:oaktrust.library.tamu.edu:1969.1/158140","repository":{"repo_id":"tamu","name":"Texas A&M University","base_url":"https://oaktrust.library.tamu.edu/server/oai/request"},"display":{"title":"The Effects of Low-Level Wind Shear Orientation, Depth, and Magnitude on Low-Level Rotation in Simulated Supercell Thunderstorms","abstract":"Supercell thunderstorms simulated using the numerical model CM1 are used to analyze the effects of low-level vertical wind shear on near-ground rotation in the storm. In particular, the parameters being assessed are the orientation, magnitude, and depth of the low-level vertical wind shear. Particular emphasis is given to the effects of the shear in determining the position of the low-level outflow relative to the midlevel mesocyclone/updraft. The simulations are initialized using idealized soundings of quarter-circle, clockwise turning, with unidirectional westerly shear above 2 km hodographs. A control simulation is run without any low-level vertical wind shear to compare to the other runs. Experiments are then conducted in which the background sounding is modified by adding a low-level shear layer at one of three different orientation angles: 0° (easterly shear), 90° (southerly shear), or 180° (westerly shear). Comparing a set of simulations run for a shear layer depth of 500 meters with a shear magnitude of 7 m s^−1 , the most favorable orientation for intensifying near-ground rotation based on positioning of the outflow relative to the midlevel mesocyclone was the 0° case. The 90° case became more favorable after being run for another hour, where as the control and 180° cases did not develop favorable conditions. Changing the shear layer depth to 250 meters gives similar results, but when the shear layer depth is changed to 1 kilometer the most favorable simulation became the control. Finally, when the magnitude of the shear was increased to 15 m s^ −1 , none of the cases was found to be favorable, as the outflow was not found to be positioned in any of the simulations below the midlevel mesocyclone. Statistically, a significant negative correlation was found between the maximum near-ground vertical vorticity/circulation and the distance between the maximum near-ground rotation and the midlevel mesocyclone. When this distance decreased, the vertical vorticity/circulation increased, suggesting that the positioning of the outflow beneath the midlevel mesocyclone plays a key role in amplifying the surface rotation. For the particular sounding used in this study, a low-level shear orientation produces the most favorable positioning of the outflow beneath the mesocyclone, and thus lead to the strongest surface rotation among the cases considered.","abstract_html":"Supercell thunderstorms simulated using the numerical model CM1 are used to analyze the effects of low-level vertical wind shear on near-ground rotation in the storm. In particular, the parameters being assessed are the orientation, magnitude, and depth of the low-level vertical wind shear. Particular emphasis is given to the effects of the shear in determining the position of the low-level outflow relative to the midlevel mesocyclone/updraft. The simulations are initialized using idealized soundings of quarter-circle, clockwise turning, with unidirectional westerly shear above 2 km hodographs. A control simulation is run without any low-level vertical wind shear to compare to the other runs. Experiments are then conducted in which the background sounding is modified by adding a low-level shear layer at one of three different orientation angles: 0° (easterly shear), 90° (southerly shear), or 180° (westerly shear). Comparing a set of simulations run for a shear layer depth of 500 meters with a shear magnitude of 7 m s^−1 , the most favorable orientation for intensifying near-ground rotation based on positioning of the outflow relative to the midlevel mesocyclone was the 0° case. The 90° case became more favorable after being run for another hour, where as the control and 180° cases did not develop favorable conditions. Changing the shear layer depth to 250 meters gives similar results, but when the shear layer depth is changed to 1 kilometer the most favorable simulation became the control. Finally, when the magnitude of the shear was increased to 15 m s^ −1 , none of the cases was found to be favorable, as the outflow was not found to be positioned in any of the simulations below the midlevel mesocyclone. Statistically, a significant negative correlation was found between the maximum near-ground vertical vorticity/circulation and the distance between the maximum near-ground rotation and the midlevel mesocyclone. When this distance decreased, the vertical vorticity/circulation increased, suggesting that the positioning of the outflow beneath the midlevel mesocyclone plays a key role in amplifying the surface rotation. For the particular sounding used in this study, a low-level shear orientation produces the most favorable positioning of the outflow beneath the mesocyclone, and thus lead to the strongest surface rotation among the cases considered.","abstract_has_math":false,"creators":["Guarriello, Felicia Rose"],"institution":"Texas A & M University","degree_name":"Master of Science","degree_level":"Masters","degree_discipline":"Atmospheric Sciences","degree_department":null,"school":null,"contributors":[],"advisors":["Nowotarski, Christopher","Epifanio, Craig"],"committee_chairs":[],"committee_members":["Hetland, Robert"],"year":2016,"date_issued":"2016-08-05","date_published":"2016-08-05","updated_at":"2026-08-21T16:48:40Z","subjects":["low-level shear","supercell"],"languages":["en"],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://hdl.handle.net/1969.1/158140","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"source_record":{"url":"https://oaktrust.library.tamu.edu/server/oai/request?verb=GetRecord&metadataPrefix=dim&identifier=oai%3Aoaktrust.library.tamu.edu%3A1969.1%2F158140","prefix":"dim"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.advisor","label":"Advisor","values":["Nowotarski, Christopher","Epifanio, Craig"]},{"key":"dc:contributor.committeemember","label":"Committee Member","values":["Hetland, Robert"]},{"key":"dc:creator","label":"Author","values":["Guarriello, Felicia Rose"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2016-09-22T19:54:23Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2016-09-22T19:54:23Z"]},{"key":"dc:date.issued","label":"Date","values":["2016-08-05"]},{"key":"dc:type","label":"Dc Type","values":["Thesis"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Atmospheric Sciences"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Masters"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Master of Science"]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["Texas A & M University"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["low-level shear","supercell"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language.iso","label":"Language (ISO)","values":["en"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["https://hdl.handle.net/1969.1/158140"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["Supercell thunderstorms simulated using the numerical model CM1 are used to analyze the effects of low-level vertical wind shear on near-ground rotation in the storm. In particular, the parameters being assessed are the orientation, magnitude, and depth of the low-level vertical wind shear. Particular emphasis is given to the effects of the shear in determining the position of the low-level outflow relative to the midlevel mesocyclone/updraft. The simulations are initialized using idealized soundings of quarter-circle, clockwise turning, with unidirectional westerly shear above 2 km hodographs. A control simulation is run without any low-level vertical wind shear to compare to the other runs. Experiments are then conducted in which the background sounding is modified by adding a low-level shear layer at one of three different orientation angles: 0° (easterly shear), 90° (southerly shear), or 180° (westerly shear). Comparing a set of simulations run for a shear layer depth of 500 meters with a shear magnitude of 7 m s^−1 , the most favorable orientation for intensifying near-ground rotation based on positioning of the outflow relative to the midlevel mesocyclone was the 0° case. The 90° case became more favorable after being run for another hour, where as the control and 180° cases did not develop favorable conditions. Changing the shear layer depth to 250 meters gives similar results, but when the shear layer depth is changed to 1 kilometer the most favorable simulation became the control. Finally, when the magnitude of the shear was increased to 15 m s^ −1 , none of the cases was found to be favorable, as the outflow was not found to be positioned in any of the simulations below the midlevel mesocyclone. Statistically, a significant negative correlation was found between the maximum near-ground vertical vorticity/circulation and the distance between the maximum near-ground rotation and the midlevel mesocyclone. When this distance decreased, the vertical vorticity/circulation increased, suggesting that the positioning of the outflow beneath the midlevel mesocyclone plays a key role in amplifying the surface rotation. For the particular sounding used in this study, a low-level shear orientation produces the most favorable positioning of the outflow beneath the mesocyclone, and thus lead to the strongest surface rotation among the cases considered."]},{"key":"dc:format.mimetype","label":"Dc Format Mimetype","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["The Effects of Low-Level Wind Shear Orientation, Depth, and Magnitude on Low-Level Rotation in Simulated Supercell Thunderstorms"]}]}],"canonical_facts":{"dc:contributor.advisor":["Nowotarski, Christopher","Epifanio, Craig"],"dc:contributor.committeemember":["Hetland, Robert"],"dc:creator":["Guarriello, Felicia Rose"],"dc:date.accessioned":["2016-09-22T19:54:23Z"],"dc:date.available":["2016-09-22T19:54:23Z"],"dc:date.issued":["2016-08-05"],"dc:description.abstract":["Supercell thunderstorms simulated using the numerical model CM1 are used to analyze the effects of low-level vertical wind shear on near-ground rotation in the storm. In particular, the parameters being assessed are the orientation, magnitude, and depth of the low-level vertical wind shear. Particular emphasis is given to the effects of the shear in determining the position of the low-level outflow relative to the midlevel mesocyclone/updraft. The simulations are initialized using idealized soundings of quarter-circle, clockwise turning, with unidirectional westerly shear above 2 km hodographs. A control simulation is run without any low-level vertical wind shear to compare to the other runs. Experiments are then conducted in which the background sounding is modified by adding a low-level shear layer at one of three different orientation angles: 0° (easterly shear), 90° (southerly shear), or 180° (westerly shear). Comparing a set of simulations run for a shear layer depth of 500 meters with a shear magnitude of 7 m s^−1 , the most favorable orientation for intensifying near-ground rotation based on positioning of the outflow relative to the midlevel mesocyclone was the 0° case. The 90° case became more favorable after being run for another hour, where as the control and 180° cases did not develop favorable conditions. Changing the shear layer depth to 250 meters gives similar results, but when the shear layer depth is changed to 1 kilometer the most favorable simulation became the control. Finally, when the magnitude of the shear was increased to 15 m s^ −1 , none of the cases was found to be favorable, as the outflow was not found to be positioned in any of the simulations below the midlevel mesocyclone. Statistically, a significant negative correlation was found between the maximum near-ground vertical vorticity/circulation and the distance between the maximum near-ground rotation and the midlevel mesocyclone. When this distance decreased, the vertical vorticity/circulation increased, suggesting that the positioning of the outflow beneath the midlevel mesocyclone plays a key role in amplifying the surface rotation. For the particular sounding used in this study, a low-level shear orientation produces the most favorable positioning of the outflow beneath the mesocyclone, and thus lead to the strongest surface rotation among the cases considered."],"dc:format.mimetype":["application/pdf"],"dc:identifier.uri":["https://hdl.handle.net/1969.1/158140"],"dc:language.iso":["en"],"dc:subject":["low-level shear","supercell"],"dc:title":["The Effects of Low-Level Wind Shear Orientation, Depth, and Magnitude on Low-Level Rotation in Simulated Supercell Thunderstorms"],"dc:type":["Thesis"],"thesis:degree_discipline":["Atmospheric Sciences"],"thesis:degree_level":["Masters"],"thesis:degree_name":["Master of Science"],"thesis:institution_name":["Texas A & M University"]},"updated_at":"2026-08-21T16:48:40Z"}