Title: Measurement report: Cloud condensation nuclei activity and its variation with organic oxidation level and volatility observed during an aerosol life cycle intensive operational period (ALC-IOP)

Abstract

Cloud condensation nuclei (CCN) spectrum and the CCN activated fraction of size-resolved aerosols (SR-CCN) were measured at a rural site on Long Island during the Department of Energy (DOE) aerosol life cycle intensive operational period (ALC-IOP) from 15 July to 15 August 2011. During the last week of the ALC-IOP, the dependence of the activated fraction on aerosol volatility was characterized by sampling downstream of a thermodenuder (TD) operated at temperatures up to 100°C. Here we present aerosol properties, including aerosol total number concentration, CCN spectrum, and the CCN hygroscopicity, for air masses of representative origins during the ALC-IOP. The hygroscopicity of organic species in the aerosol is derived from CCN hygroscopicity and chemical composition. The dependence of organic hygroscopicity on the organic oxidation level (e.g., atomic O:C ratio) agrees well with theoretical predictions and results from previous laboratory and field studies. The derived κ_org and O:C ratio first increase as TD temperature increases from 20°C (i.e., ambient temperature) to 50 or 75°C and then decrease as TD temperature further increases to 100°C. The initial increases of O:C and κ_org with TD temperature below 50°C are likely due to evaporation of more volatile organics with relatively lower O:C and hygroscopicitymore » such as primary organic aerosol. At the high TD temperatures, the decreases of O:C and κ_org indicate that evaporated organics were more oxygenated and had lower molecular weights. These trends are different from previous laboratory experiments and field observations, which reported that organic O:C increased monotonically with increasing TD temperature, whereas κ_org decreased with the TD temperature. One possible reason is that previous studies were either focused on laboratory-generated secondary organic aerosol (SOA) or based on field observations at locations more dominated by SOA.« less

Authors:

Mei, Fan ;

• Search DOE PAGES for author "Mei, Fan"
• Search DOE PAGES for ORCID "0000-0003-4285-2749"

Wang, Jian ;

• Search DOE PAGES for author "Wang, Jian"
• Search DOE PAGES for ORCID "0000-0002-2815-4170"

Zhou, Shan ;

• Search DOE PAGES for author "Zhou, Shan"
• Search DOE PAGES for ORCID "0000-0001-5031-1024"

Zhang, Qi ;

• Search DOE PAGES for author "Zhang, Qi"
• Search DOE PAGES for ORCID "0000-0002-5203-8778"

Collier, Sonya; Xu, Jianzhong

Publication Date:

Thu Sep 02 00:00:00 EDT 2021

Research Org.:

Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Atmospheric Radiation Measurement (ARM) Data Center; Washington Univ., St. Louis, MO (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Biological and Environmental Research (BER)

Contributing Org.:

Argonne National Lab. (ANL); Oak Ridge National Lab. (ORNL)

OSTI Identifier:

1818607

Alternate Identifier(s):

OSTI ID: 1820930; OSTI ID: 1837830

Grant/Contract Number:  

SC0007178; FG02-11ER65293; SC0020259; SC0021017

Resource Type:

Published Article

Journal Name:

Atmospheric Chemistry and Physics (Online)

Additional Journal Information:

Journal Name: Atmospheric Chemistry and Physics (Online) Journal Volume: 21 Journal Issue: 17; Journal ID: ISSN 1680-7324

Publisher:

Copernicus GmbH

Country of Publication:

Germany

Language:

English

Subject:

54 ENVIRONMENTAL SCIENCES