{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/83217"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/83217","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Physical and Chemical Properties of Laboratory and Ambient Aerosols Related to Climate Change","abstract":"This study summarizes the evaluation of closure when measuring and modeling aerosol optical properties as a function of RH in a laboratory and reports measured ambient aerosol optical and chemical properties for an anthropogenically perturbed continental US site from 1995 to 2000. The optical closure experiment was completed in a laboratory set-up for NaCl, (NH4)2SO 4 and NH4NO3 aerosol using an RH scanning nephelometry system. Correcting for nephelometer non-idealities and RH of the sample improved the agreement between measured and predicted total scattering coefficients (sigmasp) at RH = 80% from 35% to 11%. The closure experiment revealed the importance of keeping the nephelometry system isothermal when measuring particle scattering coefficients as a function of RH or as particles exist in the ambient environment. Corrections based on the laboratory results were applied to ambient optical measurements. The averaged hygroscopic growth factor (f(RH = 82%)) at 550 nm was 1.74 +/- 0.31 for sub-micrometer particles for the site. Chemical analysis of submicrometer particles revealed that approximately 50% of the ambient aerosol mass was SO4 and NH4. Direct aerosol radiative forcing (DARF) for the site was estimated to be -1.3 W/m2 at an ambient RH of 72%. Therefore the net effect of ambient aerosols at the site is to cool the atmosphere.","abstract_html":"This study summarizes the evaluation of closure when measuring and modeling aerosol optical properties as a function of RH in a laboratory and reports measured ambient aerosol optical and chemical properties for an anthropogenically perturbed continental US site from 1995 to 2000. The optical closure experiment was completed in a laboratory set-up for NaCl, (NH4)2SO 4 and NH4NO3 aerosol using an RH scanning nephelometry system. Correcting for nephelometer non-idealities and RH of the sample improved the agreement between measured and predicted total scattering coefficients (sigmasp) at RH = 80% from 35% to 11%. The closure experiment revealed the importance of keeping the nephelometry system isothermal when measuring particle scattering coefficients as a function of RH or as particles exist in the ambient environment. Corrections based on the laboratory results were applied to ambient optical measurements. The averaged hygroscopic growth factor (f(RH = 82%)) at 550 nm was 1.74 +/- 0.31 for sub-micrometer particles for the site. Chemical analysis of submicrometer particles revealed that approximately 50% of the ambient aerosol mass was SO4 and NH4. Direct aerosol radiative forcing (DARF) for the site was estimated to be -1.3 W/m2 at an ambient RH of 72%. Therefore the net effect of ambient aerosols at the site is to cool the atmosphere.","abstract_has_math":false,"creators":["Kus, Pinar"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"Ph.D.","degree_level":"Dissertation","degree_discipline":"Civl and Environmental Engineering","degree_department":null,"school":null,"contributors":["Rood, Mark J."],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2015,"date_issued":"2015-09-25T21:03:37Z","date_published":"2015-09-25T21:03:37Z","updated_at":"2026-07-22T22:26:20Z","subjects":["Engineering, Environmental"],"languages":["eng"],"rights":[],"rights_urls":[],"identifier_entries":[{"key":"dc:identifier","label":"Identifier","values":["(MiAaPQ)AAI3101891"],"render_values":[{"text":"(MiAaPQ)AAI3101891","href":null,"code":true}]}]},"links":{"outbound_url":"http://hdl.handle.net/2142/83217","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Rood, Mark J."]},{"key":"dc:creator","label":"Author","values":["Kus, Pinar"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2015-09-25T21:03:37Z","10000-01-01","2003"]},{"key":"dc:type","label":"Dc Type","values":["text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Civl and Environmental Engineering"]},{"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":["Engineering, Environmental"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["eng"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["http://hdl.handle.net/2142/83217","(MiAaPQ)AAI3101891"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["This study summarizes the evaluation of closure when measuring and modeling aerosol optical properties as a function of RH in a laboratory and reports measured ambient aerosol optical and chemical properties for an anthropogenically perturbed continental US site from 1995 to 2000. 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The optical closure experiment was completed in a laboratory set-up for NaCl, (NH4)2SO 4 and NH4NO3 aerosol using an RH scanning nephelometry system. Correcting for nephelometer non-idealities and RH of the sample improved the agreement between measured and predicted total scattering coefficients (sigmasp) at RH = 80% from 35% to 11%. The closure experiment revealed the importance of keeping the nephelometry system isothermal when measuring particle scattering coefficients as a function of RH or as particles exist in the ambient environment. Corrections based on the laboratory results were applied to ambient optical measurements. The averaged hygroscopic growth factor (f(RH = 82%)) at 550 nm was 1.74 +/- 0.31 for sub-micrometer particles for the site. Chemical analysis of submicrometer particles revealed that approximately 50% of the ambient aerosol mass was SO4 and NH4. Direct aerosol radiative forcing (DARF) for the site was estimated to be -1.3 W/m2 at an ambient RH of 72%. 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