{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/20476"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/20476","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Modeling study of tropical nonsquall and squall clusters","abstract":"A numerical cloud model in both two-dimensional and three-dimensional form is used to investigate the dynamical differences between non-squall and squall line convection in the tropics. Two-dimensional simulations with cold-pool dynamics indicate that the simulated convective system propagates as a slow-moving multicellular squall line, in contrast to the nearly stationary observed non-squall convective line. Environmental winds are not included in the two-dimensional simulations. To assess their effect on the behavior and general structure of non-squall convection, three-dimensional simulations are performed. In addition, oceanic squall lines are also studied.","abstract_html":"A numerical cloud model in both two-dimensional and three-dimensional form is used to investigate the dynamical differences between non-squall and squall line convection in the tropics. Two-dimensional simulations with cold-pool dynamics indicate that the simulated convective system propagates as a slow-moving multicellular squall line, in contrast to the nearly stationary observed non-squall convective line. Environmental winds are not included in the two-dimensional simulations. To assess their effect on the behavior and general structure of non-squall convection, three-dimensional simulations are performed. In addition, oceanic squall lines are also studied.","abstract_has_math":false,"creators":["Chin, Hung-Neng Steve"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"Ph.D.","degree_level":"Dissertation","degree_discipline":"Atmospheric Science","degree_department":null,"school":null,"contributors":["Wilhelmson, Robert B."],"advisors":[],"committee_chairs":[],"committee_members":[],"year":null,"date_issued":"10000-01-01","date_published":"10000-01-01","updated_at":"2026-07-22T22:25:16Z","subjects":["Physics, Atmospheric Science"],"languages":["eng"],"rights":["Copyright 1990 Chin, Hung-Neng Steve"],"rights_urls":[],"identifier_entries":[{"key":"dc:identifier","label":"Identifier","values":["AAI9026157","(UMI)AAI9026157"],"render_values":[{"text":"AAI9026157","href":null,"code":true},{"text":"(UMI)AAI9026157","href":null,"code":true}]}]},"links":{"outbound_url":"http://hdl.handle.net/2142/20476","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Wilhelmson, Robert B."]},{"key":"dc:creator","label":"Author","values":["Chin, Hung-Neng Steve"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["10000-01-01","1990","2011-05-07T12:40:19Z"]},{"key":"dc:type","label":"Dc Type","values":["text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Atmospheric Science"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Dissertation"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Ph.D."]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["University of Illinois at Urbana-Champaign"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Physics, Atmospheric Science"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["eng"]},{"key":"dc:rights","label":"Dc Rights","values":["Copyright 1990 Chin, Hung-Neng Steve"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["AAI9026157","(UMI)AAI9026157","http://hdl.handle.net/2142/20476"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["A numerical cloud model in both two-dimensional and three-dimensional form is used to investigate the dynamical differences between non-squall and squall line convection in the tropics. Two-dimensional simulations with cold-pool dynamics indicate that the simulated convective system propagates as a slow-moving multicellular squall line, in contrast to the nearly stationary observed non-squall convective line. Environmental winds are not included in the two-dimensional simulations. To assess their effect on the behavior and general structure of non-squall convection, three-dimensional simulations are performed. In addition, oceanic squall lines are also studied.","An observed non-squall and a squall line associated with the passage of a easterly wave are simulated to study their different dynamic behavior, and to identify the environmental parameters (e.g., wind and thermodynamical structure) favoring the development of one or the other. The same model external parameters (i.e., random temperature perturbations and large-scale forcing) are used for the control non-squall and squall simulations. The effect of large-scale low-level convergence on the organization of tropical mesoscale convective systems (MCSs) is also explored. The results indicate that the dynamic structure of tropical MCSs is strongly controlled by the environmental wind and moisture structure.","Model simulations show that the dominant easterly shear and weak convectively unstable environment favor the occurrence of non-squall line convection. Both the bell-shaped large-scale ascent and the environmental winds together play a crucial role in aligning the initially random distributed convective cells. Once the aligned structure forms, the dominant easterly shear further elongate the existing line structure. In contrast, the strong veering shear and more convectively unstable environment lead to the development of intense oceanic squall lines. Under the strong veering shear environment with a drier mid-level layer, a long-lasting develops and produces a strong updraft and precipitation to generate an intense low-level cold pool, which is advected southward by the environmental northerly wind, and trigger new successive cells to the south along the leading edge of the cold pool to form an arc-shaped squall line with a fast propagation speed.","The non-squall convection is aligned roughly parallel to the environmental wind shear and to the low-level convergence line, while the developing squall line is aligned approximately perpendicular to the environmental wind shear. Once the organized structure has developed, the large-scale forcing has no further effect on maintaining the dynamical organization of both non-squall and squall line systems. However, it does contribute positively to the total precipitation for the non-squall system, but negatively for the squall line system.","Made available in DSpace on 2011-05-07T12:40:19Z (GMT). No. of bitstreams: 2 license.txt: 4922 bytes, checksum: 910b249b4beec47e7ab768910c8f966f (MD5) 9026157.pdf: 8788648 bytes, checksum: 61da07fdb39740d2474d9b65eebe847d (MD5) Previous issue date: 1990","Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Howard Ding (hding2@illinois.edu) on 2011-05-07T14:44:09Z Item is restricted indefinitely.","Restriction data tranferred 2014-07-01T11:19:24-05:00 Original Data Group with Access UIUC Users [automated] Release Date: none Reason: ETDs are only available to UIUC Users without author permission","ETDs are only available to UIUC Users without author permission","U of I Only"]},{"key":"dc:title","label":"Title","values":["Modeling study of tropical nonsquall and squall clusters"]}]}],"canonical_facts":{"dc:contributor":["Wilhelmson, Robert B."],"dc:creator":["Chin, Hung-Neng Steve"],"dc:date":["10000-01-01","1990","2011-05-07T12:40:19Z"],"dc:description":["A numerical cloud model in both two-dimensional and three-dimensional form is used to investigate the dynamical differences between non-squall and squall line convection in the tropics. Two-dimensional simulations with cold-pool dynamics indicate that the simulated convective system propagates as a slow-moving multicellular squall line, in contrast to the nearly stationary observed non-squall convective line. Environmental winds are not included in the two-dimensional simulations. To assess their effect on the behavior and general structure of non-squall convection, three-dimensional simulations are performed. In addition, oceanic squall lines are also studied.","An observed non-squall and a squall line associated with the passage of a easterly wave are simulated to study their different dynamic behavior, and to identify the environmental parameters (e.g., wind and thermodynamical structure) favoring the development of one or the other. The same model external parameters (i.e., random temperature perturbations and large-scale forcing) are used for the control non-squall and squall simulations. The effect of large-scale low-level convergence on the organization of tropical mesoscale convective systems (MCSs) is also explored. The results indicate that the dynamic structure of tropical MCSs is strongly controlled by the environmental wind and moisture structure.","Model simulations show that the dominant easterly shear and weak convectively unstable environment favor the occurrence of non-squall line convection. Both the bell-shaped large-scale ascent and the environmental winds together play a crucial role in aligning the initially random distributed convective cells. Once the aligned structure forms, the dominant easterly shear further elongate the existing line structure. In contrast, the strong veering shear and more convectively unstable environment lead to the development of intense oceanic squall lines. Under the strong veering shear environment with a drier mid-level layer, a long-lasting develops and produces a strong updraft and precipitation to generate an intense low-level cold pool, which is advected southward by the environmental northerly wind, and trigger new successive cells to the south along the leading edge of the cold pool to form an arc-shaped squall line with a fast propagation speed.","The non-squall convection is aligned roughly parallel to the environmental wind shear and to the low-level convergence line, while the developing squall line is aligned approximately perpendicular to the environmental wind shear. Once the organized structure has developed, the large-scale forcing has no further effect on maintaining the dynamical organization of both non-squall and squall line systems. However, it does contribute positively to the total precipitation for the non-squall system, but negatively for the squall line system.","Made available in DSpace on 2011-05-07T12:40:19Z (GMT). No. of bitstreams: 2 license.txt: 4922 bytes, checksum: 910b249b4beec47e7ab768910c8f966f (MD5) 9026157.pdf: 8788648 bytes, checksum: 61da07fdb39740d2474d9b65eebe847d (MD5) Previous issue date: 1990","Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Howard Ding (hding2@illinois.edu) on 2011-05-07T14:44:09Z Item is restricted indefinitely.","Restriction data tranferred 2014-07-01T11:19:24-05:00 Original Data Group with Access UIUC Users [automated] Release Date: none Reason: ETDs are only available to UIUC Users without author permission","ETDs are only available to UIUC Users without author permission","U of I Only"],"dc:identifier":["AAI9026157","(UMI)AAI9026157","http://hdl.handle.net/2142/20476"],"dc:language":["eng"],"dc:rights":["Copyright 1990 Chin, Hung-Neng Steve"],"dc:subject":["Physics, Atmospheric Science"],"dc:title":["Modeling study of tropical nonsquall and squall clusters"],"dc:type":["text"],"thesis:degree_discipline":["Atmospheric Science"],"thesis:degree_level":["Dissertation"],"thesis:degree_name":["Ph.D."],"thesis:institution_name":["University of Illinois at Urbana-Champaign"]},"updated_at":"2026-07-22T22:25:16Z"}