{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/72453"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/72453","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Dynamics and Predictability of the Intraseasonal Disturbances","abstract":"We are interested in establishing how the instability properties of the background circulation might be related to the observed intraseasonal variability. We focus on the intraseasonal variability in two Northern Hemispheric winters with distinctly different background conditions. The daily 500-mb global streamfunction fields are used. The year-to-year variations of the intraseasonal variability are closely related to the variations of the corresponding seasonal-mean flow.","abstract_html":"We are interested in establishing how the instability properties of the background circulation might be related to the observed intraseasonal variability. We focus on the intraseasonal variability in two Northern Hemispheric winters with distinctly different background conditions. The daily 500-mb global streamfunction fields are used. The year-to-year variations of the intraseasonal variability are closely related to the variations of the corresponding seasonal-mean flow.","abstract_has_math":false,"creators":["Chang, Jen-Cheng"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"Ph.D.","degree_level":"Dissertation","degree_discipline":"Atmospheric Sciences","degree_department":null,"school":null,"contributors":["Mak, Mankin"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2014,"date_issued":"2014-12-17T22:39:28Z","date_published":"2014-12-17T22:39:28Z","updated_at":"2026-07-22T22:26:06Z","subjects":["Physics, Atmospheric Science"],"languages":[],"rights":[],"rights_urls":[],"identifier_entries":[{"key":"dc:identifier","label":"Identifier","values":["(UMI)AAI9411580"],"render_values":[{"text":"(UMI)AAI9411580","href":null,"code":true}]}]},"links":{"outbound_url":"http://hdl.handle.net/2142/72453","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Mak, Mankin"]},{"key":"dc:creator","label":"Author","values":["Chang, Jen-Cheng"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2014-12-17T22:39:28Z","10000-01-01","1993"]},{"key":"dc:type","label":"Dc Type","values":["text"]},{"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":["Physics, Atmospheric Science"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["http://hdl.handle.net/2142/72453","(UMI)AAI9411580"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["We are interested in establishing how the instability properties of the background circulation might be related to the observed intraseasonal variability. We focus on the intraseasonal variability in two Northern Hemispheric winters with distinctly different background conditions. The daily 500-mb global streamfunction fields are used. The year-to-year variations of the intraseasonal variability are closely related to the variations of the corresponding seasonal-mean flow.","A normal-mode instability analysis of a linear barotropic model reveals, however, that the seasonal-mean basic flow of the season with a stronger intraseasonal variability is in fact barotropically more stable than that of the weaker season. A DEOF (Dynamical-Empirical Orthogonal Function) analysis shows a fairly white spectrum in each season, implying a weak direct dynamical relation between the observed intraseasonal variability and the individual normal modes. Furthermore, the first few DEOFs are either barotropically neutral or weakly stable normal modes, but are not the more unstable modes.","A kinetic energy budget analysis confirms that the barotropic conversion process is one of the two major processes to generate the observed intraseasonal variability in NH wintertime. An optimal-mode analysis shows that about 40% of the observed intraseasonal disturbances can be potentially intensified through the non-modal instability process. The fraction of the intraseasonal kinetic energy of those growing modes has indeed increased to about 60% after 1 day. The result supports the conjecture that the non-modal barotropic instability of the seasonal-mean basic flow is important to the generation of the intraseasonal variability.","We also explore the feasibility of using a barotropic model to predict the intraseasonal flow. The predictability of the linear model is good for at most 6 days. Under certain favorable initial conditions, the model simulations can be useful for up to 10 days. The modest performance is due to the lack of other important dynamical/physical processes in the model. The initial uncertainty is only a minor issue. The high-frequency eddy forcing is essential to the simulations.","Made available in DSpace on 2014-12-17T22:39:28Z (GMT). No. of bitstreams: 1 9411580.pdf: 7120288 bytes, checksum: bb8f5739a15f2a8b8dfc8ed9f667827f (MD5) Previous issue date: 1993","Embargo set by: Seth Robbins for item 72621 Lift date: Forever Reason: Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs","Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs","U of I Only","182 p.","Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1993."]},{"key":"dc:title","label":"Title","values":["Dynamics and Predictability of the Intraseasonal Disturbances"]}]}],"canonical_facts":{"dc:contributor":["Mak, Mankin"],"dc:creator":["Chang, Jen-Cheng"],"dc:date":["2014-12-17T22:39:28Z","10000-01-01","1993"],"dc:description":["We are interested in establishing how the instability properties of the background circulation might be related to the observed intraseasonal variability. We focus on the intraseasonal variability in two Northern Hemispheric winters with distinctly different background conditions. The daily 500-mb global streamfunction fields are used. The year-to-year variations of the intraseasonal variability are closely related to the variations of the corresponding seasonal-mean flow.","A normal-mode instability analysis of a linear barotropic model reveals, however, that the seasonal-mean basic flow of the season with a stronger intraseasonal variability is in fact barotropically more stable than that of the weaker season. A DEOF (Dynamical-Empirical Orthogonal Function) analysis shows a fairly white spectrum in each season, implying a weak direct dynamical relation between the observed intraseasonal variability and the individual normal modes. Furthermore, the first few DEOFs are either barotropically neutral or weakly stable normal modes, but are not the more unstable modes.","A kinetic energy budget analysis confirms that the barotropic conversion process is one of the two major processes to generate the observed intraseasonal variability in NH wintertime. An optimal-mode analysis shows that about 40% of the observed intraseasonal disturbances can be potentially intensified through the non-modal instability process. The fraction of the intraseasonal kinetic energy of those growing modes has indeed increased to about 60% after 1 day. The result supports the conjecture that the non-modal barotropic instability of the seasonal-mean basic flow is important to the generation of the intraseasonal variability.","We also explore the feasibility of using a barotropic model to predict the intraseasonal flow. The predictability of the linear model is good for at most 6 days. Under certain favorable initial conditions, the model simulations can be useful for up to 10 days. The modest performance is due to the lack of other important dynamical/physical processes in the model. The initial uncertainty is only a minor issue. The high-frequency eddy forcing is essential to the simulations.","Made available in DSpace on 2014-12-17T22:39:28Z (GMT). No. of bitstreams: 1 9411580.pdf: 7120288 bytes, checksum: bb8f5739a15f2a8b8dfc8ed9f667827f (MD5) Previous issue date: 1993","Embargo set by: Seth Robbins for item 72621 Lift date: Forever Reason: Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs","Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs","U of I Only","182 p.","Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1993."],"dc:identifier":["http://hdl.handle.net/2142/72453","(UMI)AAI9411580"],"dc:subject":["Physics, Atmospheric Science"],"dc:title":["Dynamics and Predictability of the Intraseasonal Disturbances"],"dc:type":["text"],"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":"2026-07-22T22:26:06Z"}