Description of Method.
Scanning Mobility CCN Analysis (SMCA; Moore et al., 2010), is a novel method for obtaining fast measurements of size-resolved CCN activity and growth kinetics. This is accomplished by coupling a Condensation Particle Counter (CPC) and a Cloud Condensation Nuclei (CCN) counter with the monodisperse outlet stream of a Differential Mobility Analyzer (DMA) operated in scanning voltage mode. By applying the same inversion algorithm as is currently used for obtaining size distributions, CCN activity and droplet growth kinetics are obtained as a function of mobility size over the timescale of a SMPS scan. The performance of the new method has been evaluated by Moore et al., (2010) for activation of laboratory-generated aerosol composed of ammonium sulfate, sodium chloride and for ambient aerosol measured at the AIRMAP Thompson Farm site during the ITCT2K4 field campaign. Overall, SMCA performs remarkably well, as essentially identical CCN properties are seen measured with “scanning” and “stepping” modes of the DMA.
SMCA has been successfully used in studies focused on size-resolved CCN measurements (e.g., Padro et al., 2007; Asa-Awuku et al., 2008, 2010, 2009; Engelhart et al., 2008; Moore et al., 2008; Padro et al., 2010). The fast time response and ease of setting up SMCA are very attractive features, especially if measurements are to be carried out in polluted environments and the laboratory (where counting statistics are most favorable for rapid measurements). SMCA can also be used to study the size-resolved CCN activity in clean environments, at the expense of some temporal (or size) resolution. Finally, SMCA can be applied to commercial SMPS and CFSTGC instruments with the manufacturer-provided control software coupled with a simple post-processing routines provided on this webpage to align the instrument response curves, correct for multiple charges, and correct for the non-sphericity of the aerosol.
Downloading the SMCA package
- These codes not to be included in any commercial package, or used for any commercial applications (or for profit) without prior authorization from the code authors (RM, AN).
- The code is to be used for educational or non-profit purposes only. Any other usage must first have authorization from the authors (RM, AN).
- SMCA codes cannot be modified in any way without the author’s (RM, AN) consent.
- No portion of the SMCA source codes can be used in other codes without the author’s (RM, AN) consent.
- The codes are provided as-is, and the authors have no liability from its usage.
- Usage of the model, for any pourpose (educational, research, or other) must acknowledge the usage of these codes, i.e.
- Links to the SMCA webpage must be provided (http://nenes.eas.gatech.edu/Experiments/SMCA.html) where users can download the latest version of the code, as well as manuals and other materials.
- The main SMCA reference (Moore et al., Aerosol Science and Technology, 2010) must be cited in all publications and documentation.
- If SMCA codes are to be included within another model, some kind of agreement is required (such as an e-mail confirmation) that subsequent users will abide to the terms as outlined here.
- Documentation and publications using the SMCA codes should cite the SMCA webpage.
Want more information? Try these links:
Comments or Questions? Contact [email protected]
Development history and acknowledgments
All the codes are written in FORTRAN can run on virtually any platform with a FORTRAN compiler. The inversion processor is an Microsoft Excel worksheet (tested on Excel 97, 2003, 2007 versions). The executables provided on this page have been compiled with Lahey FORTRAN v5.6 and can run on any Windows platform (from XP and on). The FORTRAN processors are written and maintained by AN since 2004; the Excel post-processors was originally developed by AN and subsequently modified by Akua Asa-Awuku, Luz-Tereza Padro. The multiple charging algorithm and modified interface was introduced by Richard Moore. LTP also developed a version of the package that runs under the Igor environment.
We acknowledge the support of a National Science Foundation CAREER award and the National Oceanic and Atmospheric Administration under grant NA04OAR4310088. RHM acknowledges support from a DOE Graduate Research Environmental Fellowship and a Georgia Tech Presidential Fellowship. We also thank M.Bilde, A.Bougiatioti, G.Engelhart, P.Kumar, T.Lathem and T.Raymond for their feedback on the SMCA package.
References
Moore., R., Nenes, A., and Medina, J. (2010) Scanning Mobility CCN Analysis – A method for fast measurements of size resolved CCN distributions and activation kinetics, Aeros.Sci.Tech., 44, 861-871 (Preprint, Journal reprint) Note
Padro, L.T., Tkacik, D., Lathem, T., Hennigan, C., Sullivan, A.P., Weber, R.J., Huey, L.G., and Nenes, A. (2010) Investigation of cloud condensation nuclei properties and droplet growth kinetics of the water-soluble aerosol fraction in Mexico City, J.Geoph.Res., 115, D09204, doi:10.1029/2009JD013195 (Preprint, Journal reprint) Note
Asa-Awuku, A., A. Nenes, S. Gao, R.C.Flagan, and Seinfeld, J.H. (2010) Water-soluble SOA from Alkene ozonolysis: composition and droplet activation kinetics inferences from analysis of CCN activity, Atmos.Chem.Phys., 10, 1585-1597 (Online Publication, Journal reprint) Note
Asa-Awuku, A., Engelhart, G.J., Lee, B.H., Pandis, S.N., and Nenes, A. (2009) Relating CCN activity, volatility, and droplet growth kinetics of beta-caryophyllene secondary organic aerosol, Atmos. Chem. Phys., 9, 795–812 (Online Publication, Journal reprint) Note
Engelhart, G.J., Asa-Awuku, A., Nenes, A., and Pandis, S.N. (2008) CCN activity and droplet growth kinetics of fresh and aged monoterpene secondary organic aerosol, Atmos. Chem. Phys., 8, 3937-3949 (Online Publication, Journal reprint) Note
Moore, R.H, Ingall, E.D., Sorooshian, A., and Nenes, A. (2008) Molar Mass, Surface Tension, and Droplet Growth Kinetics of Marine Organics from Measurements of CCN Activity, Geoph.Res.Let., 35, doi:10.1029/2008GL033350 (Preprint, Journal reprint) Note
Asa-Awuku, A., Nenes, A., Sullivan, A.P., Hennigan, C.J. and Weber, R.J. (2008) Investigation of molar volume and surfactant characteristics of water-soluble organic compounds in biomass burning aerosol, Atmos. Chem. Phys., 8, 799-812 (Online Publication, Journal reprint) Note
Padro, L.T., Asa-Awuku, A., Morrison, R., and A. Nenes (2007) Inferring thermodynamic properties from CCN activation experiments: single-component and binary aerosols, Atmos. Chem. Phys., 7, 5263-5274 (Online Publication, Journal reprint) Note
