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At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1981

Comparison between two Aitken counters and with cloud condensation nuclei counters at the 1980 International CCN Workshop

The Pollak and the TSI 3020 counters agreed to within about 10% at concentrations below 1000 cu cm, whereas above that concentration, substantial systematic differences were observed. When the test aerosol was monodisperse and the CCN counters were operated at supersaturations that should nucleate all the aerosol, the Pollak counter read about 6% to 20% lower than the CCN counter in the concentration range from 250/cu cm to 1800/cu cm. The TSI 3020 read about 20% lower than the CCN counter at concentrations less than 1000/cu cm, and a factor of about two higher at concentrations above 1000/cu cm.

Rogers, C. F.↗
NASA NTRS1997

A Balloon-Borne Cloud Condensation Nuclei Counter

A balloon-borne instrument was constructed for observations of vertical profiles of cloud condensation nucleus (CCN) concentrations, active at 1% supersaturation. Droplet concentration in the static thermal-gradient diffusion chamber is deduced from the amount of scattered laser light detected by a photodetector. The photodetector is calibrated using a video camera and computer system to count the number of droplets produced from NaCl aerosol. Preliminary data are available from nine early morning profiles obtained at Laramie, Wyoming, between June 1995 and January 1997. To complement the CCN measurements, instruments that measure condensation nuclei (CN) and aerosols with diameter greater than 0.30 micrometers (D(sub 0.3) were also included on the balloon package. CCN concentrations exhibited a general decrease from the surface to the top of the boundary layers, were generally uniform through well-mixed layers, and show variability above well-mixed layers. In general, the structure of the CCN profile appears to be closely related to the structure in the CN and D(sub 0.3) profiles. Summer profiles generally have CCN concentration greater than 200/cu cm up to 500 mbar, whereas winter profiles are less than 200/cu cm at all levels.

Delene, David J.↗
DOE OSTI2025

CCN Measurements at Urban Site during CoURAGE

Cloud condensation nuclei (CCN) measurements were collected during CoURAGE from March - June 2025 at the BSEC urban atmospheric chemistry supersite (39.32057 N, 76.6246 W). CCN number concentrations (# cm-3) were obtained at a frequency of 1 second using a cloud condensation nuclei counter (CCN-100, Droplet Measurement Technologies). The CCN counter was operated in stepping mode, measuring CCN over a range of supersaturations from 0.2 to 1.0%. The settings of the instrument were set such that the supersaturation increased in increments of 0.2% up to the maximum supersaturation, and then decreased in increments of 0.2% down to the minimum supersaturation in a repeating cycle. The supersaturation of the instrument was calibrated weekly using ammonium sulfate. The weekly calibrated supersaturation values have been applied to the data. Data during transitions between supersaturation values were removed and replaced with a value of -999. Transitions are defined as the first 210 seconds after a new supersaturation value to ensure the instrument has stabilized following a change in supersaturation. Data were also flagged with a value of -999 if there were concerns with the function of the instrument, specifically the presence of alarm codes, fogging of the optical particle counter (1st stage monitor > 0.4 V), or a sheath to sample flow ratio outside the expected range (< 9 or > 11).

CCN number density↗
DOE OSTI2024

Coastal Cloud Chemistry during EPCAPE Field Campaign Report

For this campaign, Principal Investigator Markus Petters deployed a suite of instruments inside Lynn Russell’s container that was sited at Mt. Soledad during the Eastern Pacific Cloud Aerosol Precipitation Experiment (EPCAPE) campaign. Funding for this activity was provided by National Science Foundation Award 2410536. The instrument rack (Figure 1) included a differential mobility analyzer, a condensation particle counter, a portable optical particle spectrometer, and a continuous flow diffusion cloud condensation nuclei counter (CCN). The instruments sampled from a counterflow virtual impactor (CVI) inlet and an isokinetic inlet. The measurements provided aerosol size distribution, size-resolved CCN activity, and denuded versus undenuded CCN activity of aerosols and cloud drop residuals.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2026

CCN PI sample dataset from two BNF facilities

This dataset contains CCN instrument data files showing the sample time series of CCN concentrations in #/cm^3. The file also shows the instrument records and CCN data. The CCN_S20_data_250605000000.csv data file contains information from the S20 facility at Courteland, and the CCN_S30_data_250605000000.csv data file contains information from the S30 facility at Falkville. See the attached CCN-200 Manual for information about the variables and units with the data files.

ccn↗
DOE OSTI2025

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 UCSD Library Collection

This dataset includes guest instrument measurements and other PI products for 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-diameter 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.). The data are available at the following link: https://library.ucsd.edu/dc/collection/bb0898306q

54 ENVIRONMENTAL SCIENCES↗
NASA NTRS1981

The Third International Cloud Condensation Nuclei Workshop

Twenty-five instruments were tested, including size characterization devices and two Aitken counters. The test aerosols were supplied to the instruments by an on-line generation system, thereby eliminating the need for storage bags. Cloud condensation chambers and haze chambers are highlighted.

Kocmond, W. C.↗
DOE OSTI2025

Investigating Spatial Variability of Aerosol, Cloud Condensation Nuclei, and Ice Nucleating Particles in Mountainous Terrain Field Campaign Report

The U.S. Department of Energy Atmospheric System Research (ASR)-supported Surface Atmosphere Integrated Field Laboratory (SAIL) campaign in the East River Watershed (ERW) of the Upper Colorado River Basin in southwestern Colorado ran from fall 2021 to spring 2023. Two monitoring sites were deployed in the ERW as part of SAIL. The two sites were the Aerosol Observation System (AOS) located on Crested Butte Ski Mountain, and the second ARM Mobile Facility (AMF2), located at the Rocky Mountain Biological Laboratory in Gothic, Colorado. To gain a more comprehensive understanding of aerosols in complex, mountainous terrain, Handix Scientific deployed SAIL-Net, a distributed network of six measurement nodes spanning the domain of the SAIL research area from October 2021 to July 2023. Each node measured aerosol particles between 140 nm and 3.4 μm in diameter using a small portable optical particle spectrometer (POPS; Gao et al. 2016), cloud condensation nuclei (CNN) using a miniature CCN counter (CloudPuck), and ice nucleating particles (INP) using the time-resolved aerosol filter sampler (TRAPS; Creamean et al. 2018). Our approach was similar to other studies that aimed to better characterize and understand aerosols and gas-phase pollutants using networks of lower-cost sensors (Caubel et al. 2019, Kelly et al. 2021, Asher et al. 2022). Such studies have identified neighborhood-level variations in pollutant concentrations (Schneider et al. 2017, Popoola et al. 2018, Caubel et al. 2019). Small-scale variations such as this are poorly represented in models and poorly measured by a single monitoring system (Caubel et al. 2019). Previous work has shown the representation error (the ability of measurements to represent a larger area) increases with complex orography, leading to decreases in model accuracy (Schutgens et al. 2017). The overall goal of SAIL-Net was to improve our understanding of the variability of aerosol in the ERW, thus increasing our knowledge of aerosol-cloud interactions in this region and informing the usefulness of distributed networks of measurements for future studies. We met this goal by answering the following science questions: 1. What is the aerosol temporal variability, and how does aerosol inhomogeneity vary seasonally? Is there significant seasonal variability in sources, or are short-term meteorological conditions the most important determining factor in sources for cloud nuclei? 2. What is the aerosol spatial variability? What are the aerosol characteristics at cloud base, presumably the particles most representative of those acting as cloud nuclei? 3. How should measurement networks be designed to capture aerosol-cloud interactions, and what do they need to measure? Can a single measurement site accurately represent aerosol properties in regions of complex terrain? SAIL-Net consisted of six measurement nodes spread across the ERW near Crested Butte, Colorado. The primary objective in site placement was to select locations that captured the vertical variation in aerosol properties while also spanning the domain of the SAIL campaign. The elevation of the sites ranged from roughly 2750 m along the valley floor of the ERW to approximately 3500 m near the top of Crested Butte Mountain, which is one of the taller peaks in the ERW. The farthest distance between sites was 14 km, while the closest two sites were approximately 1 km apart. Two of the sites were collocated with the ARM SAIL sites; our instruments sat on top of one of the trailers at AOS and another one of our sites was located in a meadow just above AMF2.

54 ENVIRONMENTAL SCIENCES↗
NASA NTRS1985

Cloud Microphysics by Thermal Wave Methods

This experiments series is the first application of a low-gravity experimental technique to the study of cloud microphysics. The low-gravity environment is provided by the parabolic maneuver of NASA's KC-135 aircraft. The primary objective is to compare experimental observations of cloud droplet growth and evaporation in a convection free environment with a numerical model of the process. Beyond that, the work also involves the development and testing of low-gravity research techniques. In particular, passive methods of thermal control have been devised and used effectively. The study to date has shown that the method is particularly suitable for looking at interactions between adjoining portions of the cloud drop field and interactions of the drop field with a solid interface. After final analysis of the data, it is expected the results will shed light on the development of cloud droplet size spectra in natural clouds as well as the performance of certain types of cloud physics instrumentation, particularly continuous flow diffusion chambers and loud condensation nuclei counters.

Anderson, B. J.↗
NASA NTRS1989

Observations of condensation nuclei in the Airborne Antarctic Ozone Experiment - Implications for new particle formation and polar stratospheric cloud formation

This paper discusses the results of the ER-2 Condensation Nucleus Counter operated in the Airborne Ozone Experiment in August, September, and October 1987, providing data on the mixing ratio of aerosol condensation nuclei (CN) with diameters between about 0.02 and 1 micron. It is shown that the vertical profile of the CN mixing ratio is closely related to that of N2O, and that, between the -71 and -53 deg latitude, the location of the minima in the CN mixing ratio profile was near the 160 ppbv N2O isopleth, indicating that the processes of mixing and subsidence, which determine the inclination of that isopleth, also strongly affect the spatial distribution of the sulfate aerosol. Evidence for new sulfate particle formation is presented and related to the amount of subsidence experienced by air parcels in the formation of the polar vortex. Concentrations of CN are compared with those of larger particles (with diameters between 0.81 micron and 9.75 microns) to study polar stratospheric cloud formation mechanisms.

Wilson, J. C.↗
NASA NTRS1989

Balloon-borne measurements of aerosol, condensation nuclei, and cloud particles in the stratosphere at McMurdo Station, Antarctica, during the spring of 1987

Measurements of the vertical profile of particles with condensation nuclei counters and eight channel aerosol detectors at McMurdo Station, Antarctica, in 1987 verified observations made in 1986 concerning the absence of upwelling in the polar vortex and the presence of a condensation nuclei layer in conjunction with the ozone hole region. New observations of a bimodal aerosol size distribution, consisting of a large-particle mode mixed in with the small-particle sulfate mode, at temperatures below -79 C are consistent with the presence of nitric acid-water particles at low concentrations. Higher concentrations of large particles were observed in association with nacreous clouds. An unusual particle layer which contained enhanced concentrations of both the small-particle (sulfate) mode and the large-particle (nitric acid) mode was detected at temperatures below -85 C, suggesting simultaneous nucleation and growth phenomena. The vortex condensation nuclei layer was observed to form at the same time as the ozone hole, indicating that formation of the layer is triggered by photochemical processes and may be important in controlling ozone depletion above 22 km.

Hofmann, D. J.↗
NASA NTRS1990

Aerosol measurements in the stratocumulus project

Cloud Condensation Nuclei (CCN) and Condensation Nuclei (CN) were measured from the National Center for Atmospheric Research (NCAR) Electra throughout the marine stratocumulus project. The total particle concentration was measured with a condensation nucleus counter. The CCN were measured with the Desert Research Institute (DRI) instantaneous CCN spectrometer. This instrument simultaneously measures the concentration of aerosol active at up to 100 different critical supersaturations (Sc). This is accomplished by exposing the sample to a fixed supersaturation field and using the size of the droplets produced in this cloud chamber to deduce the Sc of the nuclei upon which they have grown. Droplet size is associated with Sc through a calibration which is accomplished by passing soluble aerosols of known size and composition through the cloud chamber. This procedure results in a calibration curve of Sc vs. droplet size. This then allows the channel number to be directly associated with Sc. Thus, number concentration vs. Sc is obtained and this is a CCN spectrum. Since the instrument operates continuously, the measurements at all Sc's are available simultaneously. Samples are drawn directly from the ambient air and data is displayed in nearly real time. Samples were integrated over times of about 10 seconds so that substantial spatial resolution is available. Calibrations were performed once or twice a day and were found to be consistent. Preliminary results are shown.

Hudson, James G.↗
DOE OSTI2025

Fast and sensitive measurements of sub-3 nm particles using Condensation Particle Counters For Atmospheric Rapid Measurements (CPC FARM)

New particle formation (NPF) is the atmospheric process whereby gas molecules react and nucleate to form detectable particles. NPF has a strong impact on Earth's radiative balance as it produces roughly half of global cloud condensation nuclei. However, the time resolution and sensitivity of current instrumentation are inadequate in measuring the size distribution of sub-3 nm particles, the particles critical for understanding NPF. Here we present the Condensation Particle Counters For Atmospheric Rapid Measurements (CPC FARM), a method to measure the concentrations of freshly nucleated particles. The CPC FARM consists of five CPCs operating in parallel, each configured to operate at different detectable particle sizes between 1–3 nm. This study explores two methods to calculate the size distribution from the differential measurements across the CPC channels. The performance of both inversion methods was tested against the size distribution measured by a pair of stepping particle mobility sizers (SMPSs) during an ambient air sampling study in Pittsburgh, PA. Observational results indicate that the CPC FARM is more accurate with higher time resolution and sensitivity in the sub-3 nm range compared to the SMPS.

Cheng, Darren [Carnegie Mellon Univ., Pittsburgh, ↗
NASA NTRS1981

Simultaneous operation of three CCN counters and an isothermal haze chamber at the 1980 International CCN Workshop

Four devices were operated for the detection and characterization of cloud condensation nuclei (CCN) and fog condensation nuclei (FCN). In chronological order of development, the CCN devices are the conventional continuous-flow diffusion chamber (CFD), the rapid-cycle CCN spectrometer, and the instantaneous CCN spectrometer. The FCN detection device is an isothermal haze chamber (IHC). These four instruments are discussed and general comments on their performance at the workshop are given.

Hudson, J. G.↗
NASA NTRS1994

Cloud-Aerosol Interactions in Tropical Storms

During the Coupled Ocean-Atmosphere Response Experiment (COARE) of the Tropical Ocean and the Global Atmosphere (TOGA) program we measured cloud and aerosol particles aboard the NASA DC-8 over the warm pool of the western Pacific. Instruments on the aircraft included a condensation nuclei counter, optical particle counters, two-dimensional shadow probes and an ice crystal replicator. The size range covered by these instruments was from =0.01 micron to 6.4 mm diameter; particle shapes were determined for particles of sizes D greater than 1 micron.

Puesschel, R. F.↗
NASA NTRS1988

Aerosol measurements in the winter/spring Antarctic stratosphere. I - Correlative measurements with ozone. II - Impact on polar stratospheric cloud theories

Aerosol measurements collected from August 25-November 3, 1986 at McMurdo Station using balloon-borne optical particle counters are examined in order to study the relationship between aerosol and ozone distribution and the formation of polar stratospheric clouds (PSCs). Ozone, aerosol, and condensation nuclei profiles, and pressure, temperature, and humidity measurements are analyzed. It is observed that the height of the stratospheric sulfate layer decreases over the period of measurement suggesting that upwelling in the votex is not important in the zone depletion process. Three theories on PSC formation are described, and the effects of the aerosol measurements on the theories are considered. The three theories are: (1) the original theory of water vapor pressure over a solution of H2SO4 of Steele et al. (1983) and Hamill and Mc Master (1984); (2) the nitric acid theory of PSCs of Toon et al. (1986) and Hamill et al. (1986); and (3) the quasi-cirrus cloud theory of Heymsfield (1986).

Hofmann, D. J.↗
DOE OSTI2025

A new technique to retrieve aerosol vertical profiles using micropulse lidar and ground-based aerosol measurements

Accurately characterizing the vertical distribution of aerosols and their cloud-forming properties is crucial for understanding aerosol-cloud interactions and their impact on climate. This study presents a novel technique for retrieving vertical profiles of aerosols, cloud condensation nuclei (CCN), and ice nucleating particles (INP) by combining micropulse lidar, radiosonde, and ground-based aerosol measurements. Herein, the technique is applied to data collected by our team at Texas A&M University during the Tracking Aerosol Convection Interactions ExpeRiment (TRACER) campaign. Ground-based aerosol size distribution and CCN counter data are used to estimate the value of the aerosol hygroscopicity parameter, κ. The derived κ, together with Mie scattering theory and the relative humidity profile from the radiosonde, is used to estimate aerosol size growth and the associated increase in backscatter at each altitude. We then correct the lidar backscatter to dry conditions to produce the dry aerosol backscatter coefficient profile. The dry aerosol backscatter coefficient profile is linearly scaled to collocated surface measurements of aerosols, CCN, and INP to produce corresponding vertical profiles. Combining lidar backscatter profiles with aerosol and cloud nucleation measurements leads to a more realistic representation of vertical distributions of aerosol properties. The method could be readily applied to lidar measurements in future field campaigns.

Chen, Bo [Texas A & M Univ., College Station, TX (↗
NASA NTRS2003

Toward Aerosol/Cloud Condensation Nuclei (CCN) Closure during CRYSTAL-FACE

During July 2002, measurements of cloud condensation nuclei were made in the vicinity of southwest Florida as part of the Cirrus Regional Study of Tropical Anvils and Cirrus Layers-Florida Area Cirrus Experiment (CRYSTAL-FACE) field campaign. These observations, at supersaturations of 0.2 and 0.85%, are presented here. The performance of each of the two CCN counters was validated through laboratory calibration and an in situ intercomparison. The measurements indicate that the aerosol sampled during the campaign was predominantly marine in character: the median concentrations were 233 cm-3 (at S = 0.2%) and 371 cm(sup -3) (at S = 0.85%). Three flights during the experiment differed from this general trend; the aerosol sampled during the two flights on 18 July was more continental in character, and the observations on 28 July indicate high spatial variability and periods of very high aerosol concentrations. This study also includes a simplified aerosol/CCN closure analysis. Aerosol size distributions were measured simultaneously with the CCN observations, and these data are used to predict a CCN concentration using Kohler theory. For the purpose of this analysis, an idealized composition of pure ammonium sulfate was assumed. The analysis indicates that in this case, there was good general agreement between the predicted and observed CCN concentrations: at S = 0.2%, N(sub predicted)/N(sub observed)= 1.047 (R(sup 2)= 0.911)); at S = 0.85%, N(sub predicted)/N(sub observed)=1.201 (R(sup 2)= 0.835)). The impacts of the compositional assumption and of including in-cloud data in the analysis are addressed. The effect of removing the data from the 28 July flight is also examined; doing so improves the result of the closure analysis at S = 0.85%. When omitting that atypical flight, N(sub predicted)/N(sub observed) = 1.085 (R(sup 2) = 0.770) at S = 0.85%.

VanReken, Timothy M.↗