Intercomparisons and Aerosol Calibrations of 12 Commercial Integrating Nephelometers of Three Manufacturers

Abstract

This study determined measured and Mie-calculated angular signal truncations for total and backscatter TSI, Inc., nephelometers, as a function of wavelength and for particles of known size and composition. Except for the total scattering channels, similar agreements as in a previous study of measured and calculated truncations were derived for submicrometer test aerosols. For the first time, instrument responses were also determined for supermicrometer test aerosols up to 1.9 m in geometric mean diameter. These supermicrometer data confirm the theoretical predictions of strong angular truncations of the total scatter signals in integrating nephelometers due to the limited range of measured forward scattering angles. Truncations up to 60% were determined for the largest measured particles. Rough empirical truncation corrections have been derived from the calibration data for Radiance Research and Ecotech nephelometers for which no detailed response characteristics exist. Intercomparisons of the nephelometers measuring urban atmospheric aerosols yield average deviations of the slope from a 1:1 relation with a TSI reference nephelometer of less than 7%. Average intercepts range between ϩ0.53 and Ϫ0.19 Mm Ϫ1 . For the Radiance Research and Ecotech nephelometers ambient regressions of the Radiance Research and Ecotech instruments with the TSI nephelometer show larger negative intercepts, which are attributed to their less well characterized optics.

Estimation of cloud condensation nuclei concentration from aerosol optical quantities: influential factors and uncertainties

“…The 470 nm σ ap was normalized to 450 nm to match the σ sp measured by the nephelometer. Anderson et al (1996) and Heintzenberg et al (2006) have reported that the uncertainty in nephelometermeasured σ sp ranges from 1 to 4 Mm −1 for one-minute averaged data. The uncertainty also depends on the magnitudes of σ sp and σ ap (Jefferson et al, 2011).…”

Study of mineral dust entrainment in the planetary boundary layer by lidar depolarisation technique

“…Additionally, the raw s sp data are corrected for truncation and non-Lambertian illumination errors using the method described by Anderson and Ogren (1998). The uncertainty in s sp is of 7% (Heintzenberg et al, 2006). The aerosol-particle absorption coefficient was measured at 637 nm, s ap (637 nm), using a MAAP with an estimated uncertainty of 12% (Petzold and Schonlinner, 2004;Petzold et al, 2005).…”

A new method to determine the mixing state of light absorbing carbonaceous using the measured aerosol optical properties and number size distributions

“…The measured HBF at 700 nm is too high, so most of them are around the calculated values of core-shell mixture. Heintzenberg et al (2006) performed a laboratory comparison study for 12 commercial nephelometers. Compared to calculated values, a systematic deviation of about -20 % was found for σ sp,700 nm of TSI 3563 nephelometer.…”