skip to main content
US FlagAn official website of the United States government
dot gov icon
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
https lock icon
Secure .gov websites use HTTPS
A lock ( lock ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.


Title: Cloud Condensation Nuclei and Printed Optical Particle Spectrometer Measurements at Mt. Soledad during EPCAPE 2023-24. In Aerosol Microphysics and Chemical Measurements at Mt. Soledad and Scripps Pier during the Eastern Pacific Cloud Aerosol Precipitation Experiment (EPCAPE) from February 2023 to February 2024
These measurements are provided by a differential mobility analyzer operated as a scanning mobility particle sizer, a printed particle optical spectrometer (POPS), and a continuous flow diffusion cloud condensation nuclei (CCN) counter. The instruments sample from either a counterflow virtual impactor inlet or an isokinetic inlet. The measurements provide the mobility aerosol size distribution (30-360 nm), optical size distribution (150 - 6000 nm), size-resolved CCN distribution (30-360 nm) at 0.2, 0.4, 0.6, 0.8, and 1.0% supersaturation. CCN measurements are performed in denuded and undenuded configuration, where denuded refers to the removal of low molecular weight organic vapors. A detailed NetCDF header is included with the datafiles. Users of these measurements are encouraged to consult with the authors about appropriate interpretation before submitting for publication, offering coauthorship where appropriate.  more » « less
Award ID(s):
2410536 2133183
PAR ID:
10537825
Author(s) / Creator(s):
; ; ; ; ; ;
Publisher / Repository:
UC San Diego Library Digital Collections
Date Published:
Subject(s) / Keyword(s):
Aerosol size distribution Mount Soledad (San Diego, Calif.) Cloud condensation nuclei
Format(s):
Medium: X Other: text/x-c; application/vnd.openxmlformats-officedocument.spreadsheetml.sheet; application/zip; application/zip; application/zip; application/vnd.openxmlformats-officedocument.spreadsheetml.sheet; application/zip; application/zip; application/zip; application/vnd.openxmlformats-officedocument.spreadsheetml.sheet; application/zip; application/zip; application/zip
Location:
(Latitude:32.8398; Longitude:-117.2494)
Right(s):
Creative Commons Attribution 4.0 International
Sponsoring Org:
National Science Foundation
More Like this
  1. This dataset includes aerosol microphysics and chemical measurements collected at Mt. Soledad and Scripps Pier during the Eastern Pacific Cloud Aerosol Precipitation Experiment (EPCAPE) from February 2023 to February 2024. The measurements include the following instruments at Mt. Soledad: High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS, Aerodyne), Scanning Electrical Mobility Spectrometer (SEMS, Brechtel Manufacturing Inc.), Aerodynamic Particle Sizer (APS, Droplet Measurements Technologies), Single Particle Soot Photometer (SP2, Drople Measurements Technologies), Meteorological Station (WXT520, Vaisala), Ozone (Teco), and trace gas proxies (Teledyne). In addition, the analyses of particle filters collected at Mt. Soledad for three dry-diameter size cuts (<1 micron, <0.5 micron, <0.18 micron) and at Scripps Pier for one dry-diametr size cut (<1 micron) by Fourier Transform Infrared (FTIR) and X-ray Fluorescence (XRF) are reported. A differential mobility analyzer operated as a scanning mobility particle sizer (SMPS, TSI Inc.), a printed particle optical spectrometer (POPS, Grimm), and a continuous flow diffusion cloud condensation nuclei (CCN, DMT) counter provide the mobility aerosol size distribution (30-360 nm), optical size distribution (150 - 6000 nm), size-resolved CCN distribution (30-360 nm) at 0.2, 0.4, 0.6, 0.8, and 1.0% supersaturation. Measurements are reported for both sampling from an isokinetic aerosol inlet and from a Counterflow Virtual Impactor (CVI, Brechtel Manufacturing Inc.). Users of these measurements are encouraged to consult with the authors about appropriate interpretation before submitting for publication, offering coauthorship where appropriate. 
    more » « less
  2. Abstract. The aerodynamic aerosol classifier (AAC) is a novel instrument that size-selects aerosol particles based on their mechanical mobility. So far, the application of an AAC for cloud condensation nuclei (CCN) activity analysis of aerosols has yet to be explored. Traditionally, a differential mobility analyzer (DMA) is used for aerosol classification in a CCN experimental setup. A DMA classifies particles based on their electrical mobility. Substituting the DMA with an AAC can eliminate multiple-charging artifacts as classification using an AAC does not require particle charging. In this work, we describe an AAC-based CCN experimental setup and CCN analysis method. We also discuss and develop equations to quantify the uncertainties associated with aerosol particle sizing. To do so, we extend the AAC transfer function analysis and calculate the measurement uncertainties of the aerodynamic diameter from the resolution of the AAC. The analysis framework has been packaged into a Python-based CCN Analysis Tool (PyCAT 1.0) open-source code, which is available on GitHub for public use. Results show that the AAC size-selects robustly (AAC resolution is 10.1, diffusion losses are minimal, and particle transmission is high) at larger aerodynamic diameters (≥∼ 85 nm). The size-resolved activation ratio is ideally sigmoidal since no charge corrections are required. Moreover, the uncertainties in the critical particle aerodynamic diameter at a given supersaturation can propagate through droplet activation, and the subsequent uncertainties with respect to the single-hygroscopicity parameter (κ) are reported. For a known aerosol such as sucrose, the κ derived from the critical dry aerodynamic diameter can be up to ∼ 50 % different from the theoretical κ. In this work, we do additional measurements to obtain dynamic shape factor information and convert the sucrose aerodynamic to volume equivalent diameter. The volume equivalent diameter applied to κ-Köhler theory improves the agreement between measured and theoretical κ. Given the limitations of the coupled AAC–CCN experimental setup, this setup is best used for low-hygroscopicity aerosol (κ≤0.2) CCN measurements. 
    more » « less
  3. Marine boundary layer (MBL) clouds are an important, though uncertain, part of Earth’s radiative budget. Previous studies have shown sources of aerosol particles in the remote MBL consist of primary sea spray, the oxidation of organic and inorganic vapors derived from the ocean, entrainment from the free troposphere, and anthropogenic pollution. The potential for these particles to become cloud condensation nuclei (CCN) varies largely dependent on their hygroscopic properties. Furthermore, when clouds form, physical processes can alter the optical properties of the cloud. This dissertation aims to identify variations in aerosol sources that affect MBL CCN concentrations and physical processes throughout the cloud lifetime that influence cloud optical properties. Ambient measurements of marine particles and clouds were made throughout two campaigns in the north Pacific and four campaigns in the north Atlantic. Both clean marine and polluted clouds were sampled. In addition, dry MBL particles were measured to identify their chemical composition and size distribution, which is necessary to identify their potential to be CCN active. The organic hygroscopicity influenced CCN concentrations and cloud optical properties significantly for particles that were mostly organic, such as ship stack and generated smoke particles. For a typical range of organic hygroscopicity the amount of reflected solar radiation varied by 2-7% for polluted conditions and less than 1% for clean conditions. Simulated droplet spectral width was shown to be more representative of observations when using a weighted distribution of cloud base heights and updraft velocities, and increased the cloud reflectivity up to 2%. Cloud top entrainment and decoupling of the MBL were found to account for a decrease in cloud radiative forcing. Cloud top entrainment was corrected for homogeneous entrainment and accounted for a decrease in radiative forcing of up to 50 Wm-2. Clustering of individual marine aerosol particles resulted in the identification of particle types derived from dimethyl-sulfide (DMS) oxidation. Two particle types were identified to come from DMS oxidation products and accounted for approximately 25% and 65% of CCN at 0.1% supersaturation during the winter and summer, respectively. One of the particle types was found to be entrained from the free troposphere. 
    more » « less
  4. Abstract. We characterize the aerosol physical and optical properties of 13 transported biomass burning (BB) events. BB events included long-rangeinfluence from fires in Alaskan and Siberian boreal forests transported to Mt. Bachelor Observatory (MBO) in the free troposphere (FT) over 8–14+ d and regional wildfires in northern California and southwestern Oregon transported to MBO in the boundary layer (BL) over 10 h to 3 d. Intensive aerosol optical properties and normalized enhancement ratios for BB events were derived from measured aerosol light scattering coefficients (σscat), aerosol light-absorbing coefficients (σabs), fine particulate matter (PM1), and carbon monoxide (CO) measurements made from July to September 2019, with particle size distribution collected from August to September. The observations showed that the Siberian BB events had a lower scattering Ångström exponent (SAE), a higher mass scattering efficiency (MSE; Δσscat/ΔPM1), and a bimodal aerosol size distribution with a higher geometric mean diameter (Dg). We hypothesize that the larger particles and associated scatteringproperties were due to the transport of fine dust alongside smoke in addition to contributions from condensation of secondary aerosol, coagulation of smaller particles, and aqueous-phase processing duringtransport. Alaskan and Siberian boreal forest BB plumes were transported long distances in the FT and characterized by lower absorptionÅngström exponent (AAE) values indicative of black carbon (BC)dominance in the radiative budget. Significantly elevated AAE values wereonly observed for BB events with <1 d transport, which suggests strong production of brown carbon (BrC) in these plumes but limited radiative forcing impacts outside of the immediate region. 
    more » « less
  5. Abstract. Accurate airborne aerosol instrumentation is required to determine thespatial distribution of ambient aerosol particles, particularly when dealingwith the complex vertical profiles and horizontal variations of atmosphericaerosols. A versatile water-based condensation particle counter (vWCPC) hasbeen developed to provide aerosol concentration measurements under variousenvironments with the advantage of reducing the health and safety concernsassociated with using butanol or other chemicals as the working fluid.However, the airborne deployment of vWCPCs is relatively limited due to thelack of characterization of vWCPC performance at reduced pressures. Giventhe complex combinations of operating parameters in vWCPCs, modeling studieshave advantages in mapping vWCPC performance. In this work, we thoroughly investigated the performance of a laminar-flowvWCPC using COMSOL Multiphysics® simulation coupled withMATLAB™. We compared it against a modified vWCPC (vWCPC model 3789, TSI,Shoreview, MN, USA). Our simulation determined the performance of particleactivation and droplet growth in the vWCPC growth tube, including thesupersaturation, Dp,kel,0 (smallest size of particle that canbe activated), Dp,kel,50 (particle size activated with 50 %efficiency) profile, and final growth particle size Dd underwide operating temperatures, inlet pressures P (30–101 kPa), and growthtube geometry (diameter D and initiator length Lini). Theeffect of inlet pressure and conditioner temperature on vWCPC 3789performance was also examined and compared with laboratory experiments. TheCOMSOL simulation result showed that increasing the temperature difference(ΔT) between conditioner temperature Tcon andinitiator Tini will reduce Dp,kel,0 and thecut-off size Dp,kel,50 of the vWCPC. In addition, loweringthe temperature midpoint(Tmid=Tcon+Tini2) increasesthe supersaturation and slightly decreases the Dp,kel. Thedroplet size at the end of the growth tube is not significantly dependent onraising or lowering the temperature midpoint but significantly decreases atreduced inlet pressure, which indirectly alters the vWCPC empirical cut-offsize. Our study shows that the current simulated growth tube geometry (D=6.3 mm and Lini=30 mm) is an optimized choice forcurrent vWCPC flow and temperature settings. The current simulation can morerealistically represent the Dp,kel for 7 nm vWCPC and alsoachieved good agreement with the 2 nm setting. Using the new simulationapproach, we provide an optimized operation setting for the 7 nm setting.This study will guide further vWCPC performance optimization forapplications requiring precise particle detection and atmospheric aerosolmonitoring. 
    more » « less