Investigations of Atmospheric Extinction Using Direct Solar Radiation Measurements Made with a Multiple Wavelength Radiometer

Shaw, Glenn E.; Reagan, John A.; Herman, Benjamin M.

doi:10.1175/1520-0450(1973)012<0374:ioaeud>2.0.co;2

Cited by 283 publications

(139 citation statements)

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“…τ pλ at 1µm) is the turbidity parameter indicating the aerosol loading and λ is the wavelength in µm (Angstrom, 1964;Shaw et al, 1973). Lower values of α indicate larger abundance of super micron aerosols (Satheesh and Moorthy, 1997).…”

Section: Size Characteristicsmentioning

confidence: 99%

Large aerosol optical depths observed at an urban location in southern India associated with rain-deficit summer monsoon season

et al. 2004

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Section: Size Characteristicsmentioning

confidence: 99%

Large aerosol optical depths observed at an urban location in southern India associated with rain-deficit summer monsoon season

et al. 2004

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“…Table 3 lists the aerosol extinction to backscatter ratio, S,, mixing layer height, mixing layer optical depth and total optical depth (actually optical depth to a height of 19.3 km) associated with each of the extinction profiles. The majority of the extinction profile retrievals yielded fairly low extinction standard deviations ( -$-15%) for the mixing layer, which is an indication that the requirements that horizontal homogeneity in / 3, and S, be constant with height were reasonably well met (Spinhirne et al, 1980 (Shaw, et al, 1973;King et al, 1980). The solar radiometer optical depth measurements provide a cross check to verify the lidar extinction retrieval.…”

Section: Electron Microscope Analysismentioning

confidence: 99%

Lidar and Balloon-Borne Cascade Impactor Measurements of Aerosols: A Case Study

Reagan

Apte

Bruhns

et al. 1984

Aerosol Science and Technology

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Aerosol size distributions, elemental components, complex refractive indices, extinction profiles and extinctionto-backscatter ratios have been measured and inferred from balloon-borne cascade impactor and lidar observations made during a cooperative joint experiment conducted during the period 4-10 April, 1980 in Tucson, AZ. Size distributions obtained from quartz crystal microbalance (QCM) cascade impactor measurements at different heights (1 to 1000 m) and times over a period of several days were fairly similar in form, being clearly bimodal in their mass distributions with the coarse particle mode being dominant. Electron microscope and energy dispersive X-ray analyses of particles deposited on the QCM stages over the particle radii range -0.5-4.0 ym revealed that the particle samples were elementally dominated by both sulfur and crustal type (Al, Ca, Mg and Si) elements. Complex refractive index estimates for a wavelength of 649 nm were obtained by comparing the lidar inferred aerosol extinction-to-backscatter ratios with theoretically computed values calculated for the impactor-derived size distributions. The real part of the index was estimated to be 1.45 for most cases, while the estimates for the imaginary part ranged between 0.000 and 0.01. Aerosol extinction coefficients calculated for the impactor-derived size distributions were found to be somewhat smaller but in fair agreement with the extinction coefficients retrieved from the lidar measurements.

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“…Optical instruments performing remote sensing measurements from the ground or from space with photometric, lidar, and extinction techniques (e.g. Shaw et al, 1973;Bitar et al, 2010;Winker et al, 2010;Salazar et al, 2013) provide indications on the size distribution and on the nature of the particles (liquid, carbon, minerals, ice, ...), generally assuming a priori hypotheses in the retrieval process. Complementarily, in situ optical measurements with optical particle counters can provide more accurate information on the local size distributions of the particles (Deshler et al, 2003).…”

Section: Introductionmentioning

confidence: 99%

LOAC: a small aerosol optical counter/sizer for ground-based and balloon measurements of the size distribution and nature of atmospheric particles – Part 1: Principle of measurements and instrument evaluation

et al. 2016

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Abstract. The study of aerosols in the troposphere and in the stratosphere is of major importance both for climate and air quality studies. Among the numerous instruments available, optical aerosol particles counters (OPCs) provide the size distribution in diameter range from about 100 nm to a few tens of µm. Most of them are very sensitive to the nature of aerosols, and this can result in significant biases in the retrieved size distribution. We describe here a new versatile optical particle/sizer counter named LOAC (Light Optical Aerosol Counter), which is light and compact enough to perform measurements not only at the surface but under all kinds of balloons in the troposphere and in the stratosphere. LOAC is an original OPC performing observations at two scattering angles. The first one is around 12 • , and is almost insensitive to the refractive index of the particles; the second one is around 60 • and is strongly sensitive to the refractive Published by Copernicus Publications on behalf of the European Geosciences Union. J.-B. Renard et al.: Size distribution and nature of atmospheric particlesindex of the particles. By combining measurement at the two angles, it is possible to retrieve the size distribution between 0.2 and 100 µm and to estimate the nature of the dominant particles (droplets, carbonaceous, salts and mineral particles) when the aerosol is relatively homogeneous. This typology is based on calibration charts obtained in the laboratory. The uncertainty for total concentrations measurements is ±20 % when concentrations are higher than 1 particle cm −3 (for a 10 min integration time). For lower concentrations, the uncertainty is up to about ±60 % for concentrations smaller than 10 −2 particle cm −3 . Also, the uncertainties in size calibration are ±0.025 µm for particles smaller than 0.6 µm, 5 % for particles in the 0.7-2 µm range, and 10 % for particles greater than 2 µm. The measurement accuracy of submicronic particles could be reduced in a strongly turbid case when concentration of particles > 3 µm exceeds a few particles cm −3 . Several campaigns of cross-comparison of LOAC with other particle counting instruments and remote sensing photometers have been conducted to validate both the size distribution derived by LOAC and the retrieved particle number density. The typology of the aerosols has been validated in well-defined conditions including urban pollution, desert dust episodes, sea spray, fog, and cloud. Comparison with reference aerosol mass monitoring instruments also shows that the LOAC measurements can be successfully converted to mass concentrations.

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Investigations of Atmospheric Extinction Using Direct Solar Radiation Measurements Made with a Multiple Wavelength Radiometer

Cited by 283 publications

References 0 publications

Large aerosol optical depths observed at an urban location in southern India associated with rain-deficit summer monsoon season

Large aerosol optical depths observed at an urban location in southern India associated with rain-deficit summer monsoon season

Lidar and Balloon-Borne Cascade Impactor Measurements of Aerosols: A Case Study

LOAC: a small aerosol optical counter/sizer for ground-based and balloon measurements of the size distribution and nature of atmospheric particles – Part 1: Principle of measurements and instrument evaluation

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