Particle sizing calibration with refractive index correction for light scattering optical particle counters and impacts upon PCASP and CDP data collected during the Fennec campaign

Rosenberg, Phil; Dean, A.; Williams, P. I.; Dorsey, J. R.; Minikin, Andreas; Pickering, M. A.; Petzold, A.

doi:10.5194/amt-5-1147-2012

Cited by 158 publications

(191 citation statements)

References 32 publications

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“…Differences in the refractive index can be accounted for with the method of Rosenberg et al (2012). The size calibration was stable over the whole campaign.…”

Section: Cas-dpol Measurementsmentioning

confidence: 99%

Comparing parameterized versus measured microphysical properties of tropical convective cloud bases during the ACRIDICON–CHUVA campaign

et al. 2017

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Abstract. The objective of this study is to validate parameterizations that were recently developed for satellite retrievals of cloud condensation nuclei supersaturation spectra, N CCN (S), at cloud base alongside more traditional parameterizations connecting N CCN (S) with cloud base updrafts and drop concentrations. This was based on the HALO aircraft measurements during the ACRIDICON-CHUVA campaign over the Amazon region, which took place in September 2014. The properties of convective clouds were measured with a cloud combination probe (CCP), a cloud and aerosol spectrometer (CAS-DPOL), and a CCN counter onboard the HALO aircraft. An intercomparison of the cloud drop size distributions (DSDs) and the cloud water content (CWC) derived from the different instruments generally shows good agreement within the instrumental uncertainties. To this end, the directly measured cloud drop concentrations (N d ) near cloud base were compared with inferred values based on the measured cloud base updraft velocity (W b ) and N CCN (S) spectra. The measurements of N d at cloud base were also compared with drop concentrations (N a ) derived on the basis of an adiabatic assumption and obtained from the vertical evolution of cloud drop effective radius (r e ) above cloud base. The measurements of N CCN (S) and W b reproduced the observed N d within the measurements uncertainties when the old (1959) Twomey's parameterization was used. The agreement between the measured and calculated N d was only within a factor of 2 with attempts to use cloud base S, as obtained from the measured W b , N d , and N CCN (S). This underscores the yet unresolved challenge of aircraft measurements of S in clouds. Importantly, the vertical evolution of r e with height reproduced the observation-based nearly adiabatic cloud base drop concentrations, N a . The combination of these results provides aircraft observational support for the various components of the satellite-retrieved methodology that was recently developed to retrieve N CCN (S) under the base of convective clouds. This parameterization can now be applied with the proper qualifications to cloud simulations and satellite retrievals.

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“…Differences in the refractive index can be accounted for with the method of Rosenberg et al (2012). The size calibration was stable over the whole campaign.…”

Section: Cas-dpol Measurementsmentioning

confidence: 99%

Comparing parameterized versus measured microphysical properties of tropical convective cloud bases during the ACRIDICON–CHUVA campaign

et al. 2017

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“…Due to (i) it is feasible to use Mie scattering calculations for estimating the number size distribution values and applying the refractive index correction (Rosenberg et al, 2012). Under those conditions LIRIC revealed a good performance regarding the fine mode aerosol concentration retrievals, especially for the height range above 2 km where the fine mode contribution is highly predominant, and the LIRIC code is less influenced by the overlap height.…”

Section: Validation Of Volume Concentration Retrievalsmentioning

confidence: 97%

“…In Figure 9, the volume concentrations retrieved with PCASP at various aircraft flight heights over the GAA, along with the effective-column volume size distribution retrieved by AERONET at 13:27 UTC are shown. The error bars on the size distributions of PCASP, denote the refractive index correction uncertainty (according to Rosenberg et al, 2012). For a direct comparison of the effective-column AERONET data (in units of m 3 m -2 ) with the height-resolved PCASP data (in units of m 3 cm -3 ), the 5 AERONET volume size distribution has been divided by a layer depth of 2±1 km (black solid and dashed lines in Figure 9).…”

Section: Validation Of Volume Concentration Retrievalsmentioning

confidence: 99%

“…However, since scattering cross section depends among other parameters also on particle's shape and refractive index, a correction regarding refractive index have to be applied. Thus, for deriving 25 calibrated particle's number density distributions we followed the procedure demonstrated by Rosenberg et al, (2012), and applied also by Tsekeri et al, (2016), for ACEMED campaign dataset.…”

Section: In-situ Airborne Aerosol Instrumentationmentioning

confidence: 99%

“…The case study of coarse mode (dust), 5 non-spherical particles, is introducing limitations regarding, the potential of in-situ instrumentation to measure size distribution in the size range above 3 m (diameter). Thus, during their study, they combined: in-situ depolarization measurements from Cloud and Aerosol Spectrometer with Polarization detection (CAS-POL; Baumgardner et al, 2001), operating at the size range 0.6-50 m (diameter), and a Passive Cavity Aerosol Spectrometer (PCASP 100X; Rosenberg et al, 2012;Cai et al, 2013) measuring aerosol size distribution in 0.1-3 m diameter range. Correcting the retrieved size 10 distributions, for refractive index assumptions, they demonstrated volume concentration discrepancies less than 20 m 3 cm -3 (0.02 ppbv) and they attributed them to CAS-POL overestimation due to the asphericity of dust particles and to the possible underestimation of LIRIC, despite the fact that the derived size distributions from CAS-POL and lidar, were found to be in a good agreement.…”

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confidence: 99%

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Validation of LIRIC aerosol concentration retrievals using airborne measurements during a biomass burning episode over Athens

Kokkalis

Amiridis

Allan

et al. 2017

Atmospheric Research

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In this paper we validate the Lidar-Radiometer Inversion Code (LIRIC) retrievals of the aerosol concentration in the fine mode, using the airborne aerosol chemical composition dataset obtained over the Greater Athens Area (GAA) in Greece, during the ACEMED campaign. The study focuses on the 2 nd of September 2011, when a long-range transported smoke 5 layer was observed in the free troposphere over Greece, in the height range from 2 to 3 km. CIMEL sun-photometric measurements revealed high AOD (~0.4 at 532 nm) and Ångström exponent values (~ 1.7 at 440/870 nm), in agreement with coincident ground-based lidar observations. Airborne chemical composition measurements performed over the GAA, revealed increased CO volume concentration (~ 110 ppbv), with 57% sulphate dominance in the PM1 fraction. For this case, we compare LIRIC retrievals of the aerosol concentration in the fine mode with the airborne Aerosol Mass Spectrometer 10 (AMS) and Passive Cavity Aerosol Spectrometer Probe (PCASP) measurements. Our analysis shows that the remote sensing retrievals are in a good agreement with the measured airborne in-situ data from 2 to 4 km. The discrepancies observed between LIRIC and airborne measurements at the lower troposphere (below 2 km), could be explained by the spatial and temporal variability of the aerosol load within the area where the airborne data were averaged along with the different time windows of the retrievals. 15

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Quantifying particle size and turbulent scale dependence of dust flux in the Sahara using aircraft measurements

Rosenberg

Parker

Ryder

et al. 2014

J. Geophys. Res. Atmos.

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The first size-resolved airborne measurements of dust fluxes and the first dust flux measurements from the central Sahara are presented and compared with a parameterization by Kok (2011a). High-frequency measurements of dust size distribution were obtained from 0.16 to 300 μm diameter, and eddy covariance fluxes were derived. This is more than an order of magnitude larger size range than previous flux estimates. Links to surface emission are provided by analysis of particle drift velocities. Number flux is described by a À2 power law between 1 and 144 μm diameter, significantly larger than the 12 μm upper limit suggested by Kok (2011a). For small particles, the deviation from a power law varies with terrain type and the large size cutoff is correlated with atmospheric vertical turbulent kinetic energy, suggesting control by vertical transport rather than emission processes. The measured mass flux mode is in the range 30-100 μm. The turbulent scales important for dust flux are from 0.1 km to 1-10 km. The upper scale increases during the morning as boundary layer depth and eddy size increase. All locations where large dust fluxes were measured had large topographical variations. These features are often linked with highly erodible surface features, such as wadis or dunes. We also hypothesize that upslope flow and flow separation over such features enhance the dust flux by transporting large particles out of the saltation layer. The tendency to locate surface flux measurements in open, flat terrain means these favored dust sources have been neglected in previous studies.

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Particle sizing calibration with refractive index correction for light scattering optical particle counters and impacts upon PCASP and CDP data collected during the Fennec campaign

Abstract: Abstract. Optical particle counters (OPCs) are used regularly for atmospheric research, measuring particle scattering cross sections to generate particle size distribution histograms.

Cited by 158 publications

References 32 publications

Comparing parameterized versus measured microphysical properties of tropical convective cloud bases during the ACRIDICON–CHUVA campaign

Comparing parameterized versus measured microphysical properties of tropical convective cloud bases during the ACRIDICON–CHUVA campaign

Validation of LIRIC aerosol concentration retrievals using airborne measurements during a biomass burning episode over Athens

Quantifying particle size and turbulent scale dependence of dust flux in the Sahara using aircraft measurements

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