{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/127149"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/127149","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"The influence of environmental conditions and cold pool generation on surface-based vs. elevated convection in a nocturnal mesoscale convective system","abstract":"Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2025-03-28 without embargo terms","abstract_html":"Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2025-03-28 without embargo terms","abstract_has_math":false,"creators":["Adams, Alexander"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"Ph.D.","degree_level":"Dissertation","degree_discipline":"Atmospheric Sciences","degree_department":null,"school":null,"contributors":["Rauber, Robert","Jewett, Brian","McFarquhar, Greg","Trapp, Robert"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2024,"date_issued":"2024-09-10","date_published":"2024-09-10","updated_at":"2026-07-22T22:25:03Z","subjects":["Nocturnal Thunderstorms","Mesoscale Convective Systems","Elevated Convection","Cold Pools","Numerical Modeling"],"languages":["en","eng"],"rights":["Copyright 2024 Alexander Adams"],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://hdl.handle.net/2142/127149","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Rauber, Robert","Jewett, Brian","McFarquhar, Greg","Trapp, Robert"]},{"key":"dc:creator","label":"Author","values":["Adams, Alexander"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2024-09-10","2024-12"]},{"key":"dc:type","label":"Dc Type","values":["text","Thesis"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Atmospheric Sciences"]},{"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":["Nocturnal Thunderstorms","Mesoscale Convective Systems","Elevated Convection","Cold Pools","Numerical Modeling"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en","eng"]},{"key":"dc:rights","label":"Dc Rights","values":["Copyright 2024 Alexander Adams"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://hdl.handle.net/2142/127149"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2025-03-28 without embargo terms","The student, Alexander Adams, accepted the attached license on 2024-09-04 at 13:32.","The student, Alexander Adams, submitted this Dissertation for approval on 2024-09-04 at 13:53.","This Dissertation was approved for publication on 2024-09-10 at 13:15.","DSpace SAF Submission Ingestion Package generated from Vireo submission #21213 on 2025-03-28 at 14:25:02","The Plains Elevated Convection at Night (PECAN) project was designed to investigate the environmental factors responsible for nocturnal Mesoscale Convective Systems (MCSs) exhibiting either surface-based or elevated convection and to identify the mechanisms by which these MCSs can propagate when conditions conducive to the propagation of similar daytime storms are absent. In this paper, we analyze the 20 June 2015 nocturnal MCS and its response to the evolving nighttime environment. Because the system matured before the nocturnal transition, this case provides a unique opportunity to explore the direct impact of the nocturnal environment on the MCS’ tendency to ingest either elevated or near-surface air. A high-resolution Weather Research and Forecasting Model (WRF) simulation of the event is used to analyze a detailed series of parcel trajectories launched from within the inflow region of the storm. The trajectory analysis demonstrated that, before the nocturnal transition, the MCS was ingesting over 80% of parcels originating from anywhere near the surface up to 2.5 km MSL. After the transition, occurring simultaneously with the stabilization of the boundary layer and intensification of the low-level jet, parcels originating from within the boundary layer were no longer being ingested by the strongest updrafts, while parcels originating from above the boundary layer continued to be efficiently ingested by the MCS’ strongest updrafts, signifying a clear transition to elevated convection following the nocturnal transition. The surface cold pool of the MCS was shown to have persisted through the duration of the simulation, even when the MCS was most elevated. To better understand the role of the cold pool in the propagation of an elevated MCS, three additional WRF simulations were carried out in which the magnitude of latent cooling due to evaporation was either doubled, halved, or removed entirely, effectively controlling the strength of the cold pool. The trajectory analysis developed in the first part of this study was then repeated for the additional simulations. It was found that in an environment where both surface-based and elevated instability were present, a stronger cold pool led to less surface-based convection, while a weaker cold pool led to more surface-based convection. During the second half of the simulation, when only elevated instability existed, all simulated storms remained elevated, but the mechanism by which the elevated convection propagated differed. A strong cold pool led to bore-like features developing in response to the forcing of the cold pool, which displaced the stable boundary layer and forced elevated, conditionally unstable air upward to its level of free convection. A weaker cold pool led to waves developing on the stable boundary layer itself that propagated ahead of the weaker surface outflow, initiating new convective updrafts."]},{"key":"dc:format","label":"Dc Format","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["The influence of environmental conditions and cold pool generation on surface-based vs. elevated convection in a nocturnal mesoscale convective system"]}]}],"canonical_facts":{"dc:contributor":["Rauber, Robert","Jewett, Brian","McFarquhar, Greg","Trapp, Robert"],"dc:creator":["Adams, Alexander"],"dc:date":["2024-09-10","2024-12"],"dc:description":["Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2025-03-28 without embargo terms","The student, Alexander Adams, accepted the attached license on 2024-09-04 at 13:32.","The student, Alexander Adams, submitted this Dissertation for approval on 2024-09-04 at 13:53.","This Dissertation was approved for publication on 2024-09-10 at 13:15.","DSpace SAF Submission Ingestion Package generated from Vireo submission #21213 on 2025-03-28 at 14:25:02","The Plains Elevated Convection at Night (PECAN) project was designed to investigate the environmental factors responsible for nocturnal Mesoscale Convective Systems (MCSs) exhibiting either surface-based or elevated convection and to identify the mechanisms by which these MCSs can propagate when conditions conducive to the propagation of similar daytime storms are absent. In this paper, we analyze the 20 June 2015 nocturnal MCS and its response to the evolving nighttime environment. Because the system matured before the nocturnal transition, this case provides a unique opportunity to explore the direct impact of the nocturnal environment on the MCS’ tendency to ingest either elevated or near-surface air. A high-resolution Weather Research and Forecasting Model (WRF) simulation of the event is used to analyze a detailed series of parcel trajectories launched from within the inflow region of the storm. The trajectory analysis demonstrated that, before the nocturnal transition, the MCS was ingesting over 80% of parcels originating from anywhere near the surface up to 2.5 km MSL. After the transition, occurring simultaneously with the stabilization of the boundary layer and intensification of the low-level jet, parcels originating from within the boundary layer were no longer being ingested by the strongest updrafts, while parcels originating from above the boundary layer continued to be efficiently ingested by the MCS’ strongest updrafts, signifying a clear transition to elevated convection following the nocturnal transition. The surface cold pool of the MCS was shown to have persisted through the duration of the simulation, even when the MCS was most elevated. To better understand the role of the cold pool in the propagation of an elevated MCS, three additional WRF simulations were carried out in which the magnitude of latent cooling due to evaporation was either doubled, halved, or removed entirely, effectively controlling the strength of the cold pool. The trajectory analysis developed in the first part of this study was then repeated for the additional simulations. It was found that in an environment where both surface-based and elevated instability were present, a stronger cold pool led to less surface-based convection, while a weaker cold pool led to more surface-based convection. During the second half of the simulation, when only elevated instability existed, all simulated storms remained elevated, but the mechanism by which the elevated convection propagated differed. A strong cold pool led to bore-like features developing in response to the forcing of the cold pool, which displaced the stable boundary layer and forced elevated, conditionally unstable air upward to its level of free convection. A weaker cold pool led to waves developing on the stable boundary layer itself that propagated ahead of the weaker surface outflow, initiating new convective updrafts."],"dc:format":["application/pdf"],"dc:identifier":["https://hdl.handle.net/2142/127149"],"dc:language":["en","eng"],"dc:rights":["Copyright 2024 Alexander Adams"],"dc:subject":["Nocturnal Thunderstorms","Mesoscale Convective Systems","Elevated Convection","Cold Pools","Numerical Modeling"],"dc:title":["The influence of environmental conditions and cold pool generation on surface-based vs. elevated convection in a nocturnal mesoscale convective system"],"dc:type":["text","Thesis"],"thesis:degree_discipline":["Atmospheric Sciences"],"thesis:degree_level":["Dissertation"],"thesis:degree_name":["Ph.D."],"thesis:institution_name":["University of Illinois at Urbana-Champaign"]},"updated_at":"2026-07-22T22:25:03Z"}