Cloud Condensation Nuclei Measurements During the SENEX 2013 Campaign: Observations, Analysis and ImpactsEPA Grant Number: R835410
Title: Cloud Condensation Nuclei Measurements During the SENEX 2013 Campaign: Observations, Analysis and Impacts
Investigators: Nenes, Athanasios
Institution: Georgia Institute of Technology
EPA Project Officer: Chung, Serena
Project Period: May 1, 2013 through April 30, 2015 (Extended to June 14, 2017)
Project Amount: $185,790
RFA: Anthropogenic Influences on Organic Aerosol Formation and Regional Climate Implications (2012) RFA Text | Recipients Lists
Research Category: Air Quality and Air Toxics , Global Climate Change , Climate Change , Air
This proposal targets the EPA-STAR Anthropogenic Influences on Organic Aerosol Formation and Regional Climate Implications, EPA-G2012-STAR-D1 question 3: “How are the climatically relevant properties of biogenic secondary organic aerosols (either optical properties or cloud interactions) impacted by anthropogenic emissions?”. The focus of this proposal is on the development and analysis of new data sets obtained from field measurements. We plan to do so by participating in the NOAA SENEX-2013 campaign (aboard the WB-P3 aircraft) and using the data to quantify the cloud & climate properties of carbonaceous aerosol.
We propose to integrate instrumentation and carry out measurements of high-resolution Cloud Condensation Nuclei (CCN) “spectra” (i.e., concentration of CCN as a function of water vapor supersaturation) onboard the NOAA WB-P3 during SENEX-2013. CCN measurements will be carried out using a Droplet Measurement Technologies Continuous-Flow Streamwise Thermal Gradient Chamber. Together with concurrent measurements of aerosol composition (AMS spectra, PILS water-soluble organic composition), aerosol size distribution and subsaturated hygroscopic water uptake, the complex relationship between size, composition, mixing state and droplet activation kinetics will be resolved with unprecedented resolution for aerosol in the Southeast United States (SE US).
The data collected will then be used to address the following scientific questions: i) What are the hygroscopicity, CCN activity and activation kinetics of SE US aerosols? How do these parameters relate to aerosol chemical composition and size distribution? What is the spatiotemporal evolution of these parameters? ii) How does the aerosol mixing state of SE US change over time and distance from their sources? How does this evolution affect CCN activity, hygroscopicity, and droplet activation kinetics of aerosol? What is the role of anthropogenic and biogenic sources on the properties? iii) What are the similarities and differences of SE US aerosol against other locations of the globe (urban, rural, continental, remote, anthropogenic, biogenic, biomass burning), and, iv) What is the direct and indirect forcing associated with SE US aerosol? How complex should be the size distribution-composition-CCN-activity relationship, to adequately represent the aerosol-CCN link?
An important outcome of the measurements and analysis thereof will be simple and comprehensive parameterizations that link aerosol chemical composition with CCN activity and droplet activation kinetics. These parameterizations can be readily used in regional and global model studies of the aerosol direct and indirect radiative forcing of climate. Data obtained in this proposed study will be made available according to the customary data-sharing agreements in EPA-sponsored field programs.