2026-09-21T12:52:21Z https://www.ideals.illinois.edu/oai-pmh

oai:www.ideals.illinois.edu:2142/83217 2023-07-11 col_2142_5131 col_2142_14770 com_2142_5130 com_2142_3518 com_2142_234

Rood, Mark J. Kus, Pinar 2015-09-25T21:03:37Z 2015-09-25T21:03:37Z 10000-01-01 2003 2003 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. Made available in DSpace on 2015-09-25T21:03:37Z (GMT). No. of bitstreams: 2 license.txt: 4848 bytes, checksum: 96035ab3f5e1c23cc7138a224ce498bd (MD5) 3101891.pdf: 6898332 bytes, checksum: 8a639a7a8d4710b3d6dae12c22f4eac7 (MD5) Previous issue date: 2003 Embargo set by: Seth Robbins for item 84498 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 123 p. Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2003. http://hdl.handle.net/2142/83217 (MiAaPQ)AAI3101891 eng Engineering, Environmental Physical and Chemical Properties of Laboratory and Ambient Aerosols Related to Climate Change text Civl and Environmental Engineering Civl and Environmental Engineering University of Illinois at Urbana-Champaign Dissertation Ph.D.