DOI: 10.5061/dryad.xksn02vtv
title: Data from: Ultrafine aerosol formation and growth in a southern California desert

description: Ultrafine aerosol number-size distributions were collected in the
 northwestern Sonoran Desert from January 2018 to April 2019 to
 assess the frequency and intensity of particle formation and
 growth events in this region. Daily and seasonal patterns of
 particle formation and growth events were compared with meteorology,
 ozone mixing ratios, air mass back-trajectories, and modeled
 boundary layer height to determine potential environmental and
 anthropogenic influences. These were supplemented with
 measurements of gas-phase biogenic volatile organic
 compounds (BVOCs) during a period of active particle formation to
 gather insights into the potential role of condensation of highly
 oxidized organic molecules. Particle formation peaked in summer,
 trending with dominant westerly winds crossing the
 southern California megalopolis with correspondingly high ozone,
 higher peak solar radiation, and greater variability in planetary
 boundary layer height. The timing of the start of growth events
 corresponded to abrupt increases in both modeled
 planetary boundary layer height and measured solar radiation.
 Formation and/or growth events occurred on 22% of days with an
 average observed diameter growth rate of 5.2 ± 2.2 nm/hr.
 Gas-phase measurements of BVOCs suggest a
 low-isoprene, high-monoterpene environment that, when combined
 with high ozone, creates ideal conditions for aerosol formation.
 These observations indicate that the formation and growth of
 ultrafine particles is common in this California desert atmosphere and
 is likely influenced by the products of anthropogenic pollutants
 and biogenic emissions.
description: Date of data collection: 2018-01 to 2019-04
 Geographic location of data collection:  Steele/Burnand
 Anza-Borrego Desert Reseach Center (33°14'25"N
 116°23'19"W), Borrego Springs, CA USA. Other
 details regarding these measurements can be found in the associated
 manuscript: Cramer K. L., Guenther, A. G., and Smith, J. N.: Ultrafine
 aerosol formation and growth in a southern California desert,
 <em>Aerosol Science and Technology</em>.
description: # Data from: Ultrafine aerosol formation and growth in a southern
 California desert Dataset DOI:
 [10.5061/dryad.xksn02vtv](10.5061/dryad.xksn02vtv) ## Description of the
 data and file structure ### Files and variables #### File List: *
 SBAB_Meteorology * SBAB_Ozone * SBAB_SizeDistribution_010518-032918 *
 SBAB_SizeDistribution_033018-051118 * SBAB_SizeDistribution_051118-062118
 * SBAB_SizeDistribution_062118-082218 *
 SBAB_SizeDistribution_082218-101618 * SBAB_SizeDistribution_101618-040219
 #### DATA-SPECIFIC INFORMATION FOR ALL DATA FILES: **File:
 SBAB_Meteorology.csv** Meteorological measurements collected between Jan
 1, 2018, and Apr 2, 2019. Presented with variables: Datetime (PST),
 Average Windspeed (m/s), Wind Direction, Total Solar Radiation (W/m²),
 Average Relative Humidity (%), Rainfall (mm), Air Temperature (°C). The
 n/a values refer to data not available, indicating a lapse in measurement.
 **File: SBAB_Ozone.csv** Calculated average ozone (ppb) calculated from on
 ozone data collected at Palm Springs and Westmorland AQMD sites. Presented
 with the variables: Datetime (PST) and Average Ozone (ppb). The n/a values
 refer to data not available, indicating a lapse in measurement. **File:
 SBAB_SizeDistribution_010518-032918.csv** Particle number size
 distributions collected between Jan 1, 2018, and March 29, 2018. Presented
 as a matrix of average particle concentration (dN/dlogDp, cm^-3) against
 date and time (PST, column 1) and midpoint bin diameter (nm, row 1). The
 n/a values refer to data not available, indicating a lapse in measurement.
 **File: SBAB_SizeDistribution_033018-051118.csv** Particle number size
 distributions collected between March 30, 2018, and May 11, 2018.
 Presented as a matrix of average particle concentration (dN/dlogDp, cm^-3)
 against date and time (PST, column 1) and midpoint bin diameter (nm, row
 1). The n/a values refer to data not available, indicating a lapse in
 measurement. **File: SBAB_SizeDistribution_051118-062118.csv** Particle
 number size distributions collected between May 11, 2018, and June 21,
 2018. Presented as a matrix of average particle concentration (dN/dlogDp,
 cm^-3) against date and time (PST, column 1) and midpoint bin diameter
 (nm, row 1). The n/a values refer to data not available, indicating a
 lapse in measurement. **File: SBAB_SizeDistribution_062118-082218.csv**
 Particle number size distributions collected between June 21, 2018, and
 Aug 22, 2018. Presented as a matrix of average particle concentration
 (dN/dlogDp, cm^-3) against date and time (PST, column 1) and midpoint bin
 diameter (nm, row 1). The n/a values refer to data not available,
 indicating a lapse in measurement. **File:
 SBAB_SizeDistribution_082218-101618.csv** Particle number size
 distributions collected between Aug 22, 2018, and Oct 16, 2018. Presented
 as a matrix of average particle concentration (dN/dlogDp, cm^-3) against
 date and time (PST, column 1) and midpoint bin diameter (nm, row 1). The
 n/a values refer to data not available, indicating a lapse in measurement.
 **File: SBAB_SizeDistribution_101618-040219.csv** Particle number size
 distributions collected between Oct 16, 2018, and Apr 2, 2019. Presented
 as a matrix of average particle concentration (dN/dlogDp, cm^-3) against
 date and time (PST, column 1) and midpoint bin diameter (nm, row 1). The
 n/a values refer to data not available, indicating a lapse in measurement.