DOI: 10.6075/j0p26w1t
title: Carbonaceous Aerosol Particle Measurements from Southeast Atmosphere Study (SOAS) 2013 in Look Rock, Tennessee, USA

description: Reading data in ICARTT Format (.ict files): Dates and times in file names are in UTC. The date and time in the file name give the date/time at which the data within the file begin. For more information on reading and understanding the data in ICARTT format visit: http://www-air.larc.nasa.gov/missions/etc/IcarttDataFormat.htm If you are using Igor Pro, you should be able to use this software to read the files: http://cires1.colorado.edu/jimenez-group/wiki/index.php/Analysis_Software#ICARTT Alternatively, you can open the .ict files directly using the import data tool in excel. Raw HDF AMS data can be analyzed with SQUIRREL and PIKA, which are available here on AMS wiki site from CU Boulder: http://cires1.colorado.edu/jimenez-group/ToFAMSResources/ToFSoftware/index.html
description: At Look Rock, TN, aerosol instruments used for this study were housed in a 20’x20’x8’ container with air conditioning set to 21 °C. The nozzle of the inlet for air sampling was ~5 m AGL and the site was at an elevation of 802 m. Ambient air was pulled isokinetically through the inlet at about 900 L min-1 using a blower to provide sufficient bypass air to keep flow conditions constant [Bates et al., 2004]. Sampled air lines were dried by diffusion driers in the van before distribution to instruments. Teflon filters (Teflo, Gelman Sciences, Ann Arbor, MI) were collected twice per day after a 2.5 μm cyclone (SCC, Rupprecht & Patashnick, East Greenbush, NY) from 0800 to 1900 and from 2000 to 0700 and four per day behind a 1 μm cyclone from 0800 to 1200, from 1200 to 1600, from 1600 to 1900, and from 2000 to 0700. Flow rates were controlled by mass flow controllers at constant volume flow rates (MCR-100SLPM, Alicat, Tucson, AZ) and recorded. A Bruker Tensor 27 FTIR spectrometer with a deuterated triglycine sulfate (DTGS) detector (Bruker, Waltham, MA) was used to scan the filters both before and after sampling. Filters were loaded each morning and solenoid valves controlled the start and stop of collection; the filter holders were mounted in a 5 ft3 refrigerator to keep the filter holders at 4℃ during and after collection each day to minimize losses due to vaporization of higher vapor pressure components and reactions that could change organic composition during storage. An automated algorithm was then applied to quantify the mass of the organic functional groups [Russell et al., 2009; Takahama et al., 2013]. Five functional groups are presented in the paper: Alkane, Amine, Alcohol, Carbonyl and Carboxylic acid groups. Other groups (Organosulfate, Organonitrate, Aromatic and Alkene group) were also fit but more than 80% of the samples were below detection limit. 42 of the Teflon filters were selected for X-ray fluorescence (XRF) (Chester Labnet, OR) of major elements above 23 amu. The mass of dust was calculated from the metals on these filters by assuming the dust is composed of Na2O, MgCO3, Al2O3, SiO2, K2O, CaCO3, TiO2, Fe2O3, MnO and BaO [Usher et al., 2003]. Samples were also collected at Centreville, Alabama, during SOAS for FTIR analysis by the same procedure. The light scattering (LS) module of the high-resolution time-of-flight aerodynamic mass spectrometer (AMS, Aerodyne Research, Inc.) uses a 405 nm source that emits a laser beam through the air beam of AMS. The length of the AMS chamber is divided by the difference between the time that the laser light is scattered and the time the chopper allows a particle to enter the chamber to give the particle velocity, which is used to determine the time to record the m/z spectra of that single particle. The AMS was operated with a 6 min duty cycle. Each cycle consisted of V-mode mass spectrum (MS) mode and particle time-of-fight (ptof) mode (2 min), W mode MS (2 min) and a light scattering mode (90 s). The remaining 30 sec in the cycle allowed time for voltage switching between modes. The particle size distribution from 10 nm to 20μm was measured by a Scanning Electrical Mobility System (SEMS, Model 2000C, Brechtel Manufacturing Incorporated), an Optical Particle Sizer (OPS, Model 3330,TSI) and an Aerodynamic Particle Sizer (APS, Model 3321, TSI). Meteorological conditions including temperature, relative humidity, precipitation, and wind direction and speed were monitored by a meteorological sensor (HMP45C RH/T, Vaisala Vantaa, Finland). Black carbon (BC), organic carbon (OC) as well as gas-phase sulfur dioxide (SO2), nitric oxide (NO), and sum of reactive and reservoir nitrogen oxides (NOy) were also measured in the permanent structure that houses the IMPROVE Great Smoky Mountains National Park site 20 m away, for which details are provided in the supplement file of [Budisulistiorini et al., 2015]. IMPROVE sampling during the study Included OC/EC, PM10, PM2.5, standard metals and common inorganic components in fine particles every three days. Density of submicron particles was estimated to be 1.5 g cm-3 by comparing the size of the AMS mass-based and SEMS number-based particle modes; AMS Collection efficiency (CE) was found to be 0.8 by comparing non-refractory mass concentration of AMS and SEMS mass concentration excluding BC and dust Measurements of volatile organic compound (VOC) mixing ratios as a function of time from June 11 to July 17, 2013 at Look Rock, TN. Size resolved cloud condensation number concentrations measured as a function of supersaturation. We also report the fraction of particles activated as well as the calculated hygroscopicity (k) parameter. Measurements of aerosol optical properties, specifically light absorption and light extinction, were made for dry particles at 405 nm and 532 nm from June 6 to July 13, 2013 at Look Rock, TN. We also report light extinction by particles humidified to ~85% RH, and from this determine the dimensionless “gammaRH” parameter to characterize the influence of water uptake on light extinction. The optical properties are reported for the sampled ambient, unaltered particles and for particles that were heated for ~20 seconds in a thermodenuder held at 250 degrees C. Measurements of volatile organic compound (VOC) mixing ratios as a function of time from June 11 to July 17, 2013 at Look Rock, TN.