Aerosol optical properties in the southeastern United States in summer – Part 1: Hygroscopic growth
| Autor: | C. A. Brock, N. L. Wagner, B. E. Anderson, A. R. Attwood, A. Beyersdorf, P. Campuzano-Jost, A. G. Carlton, D. A. Day, G. S. Diskin, T. D. Gordon, J. L. Jimenez, D. A. Lack, J. Liao, M. Z. Markovic, A. M. Middlebrook, N. L. Ng, A. E. Perring, M. S. Richardson, J. P. Schwarz, R. A. Washenfelder, A. Welti, L. Xu, L. D. Ziemba, D. M. Murphy |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2016 |
| Předmět: | |
| Zdroj: | Atmospheric Chemistry and Physics, Vol 16, Pp 4987-5007 (2016) |
| Druh dokumentu: | article |
| ISSN: | 1680-7316 1680-7324 |
| DOI: | 10.5194/acp-16-4987-2016 |
| Popis: | Aircraft observations of meteorological, trace gas, and aerosol properties were made during May–September 2013 in the southeastern United States (US) under fair-weather, afternoon conditions with well-defined planetary boundary layer structure. Optical extinction at 532 nm was directly measured at relative humidities (RHs) of ∼ 15, ∼ 70, and ∼ 90 % and compared with extinction calculated from measurements of aerosol composition and size distribution using the κ-Köhler approximation for hygroscopic growth. The calculated enhancement in hydrated aerosol extinction with relative humidity, f(RH), calculated by this method agreed well with the observed f(RH) at ∼ 90 % RH. The dominance of organic aerosol, which comprised 65 ± 10 % of particulate matter with aerodynamic diameter f(RH) values of 1.43 ± 0.67 at 70 % RH and 2.28 ± 1.05 at 90 % RH. The subsaturated κ-Köhler hygroscopicity parameter κ for the organic fraction of the aerosol must have been κ = 0.05. This subsaturated κ value for the organic aerosol in the southeastern US is broadly consistent with field studies in rural environments. A new, physically based, single-parameter representation was developed that better described f(RH) than did the widely used gamma power-law approximation. |
| Databáze: | Directory of Open Access Journals |
| Externí odkaz: |
|