Retrievals of aerosol optical and microphysical properties from Imaging Polar Nephelometer scattering measurements
A method for the retrieval of aerosol optical and microphysical properties from in situ light-scattering measurements is presented and the results are compared with existing measurement techniques. The Generalized Retrieval of Aerosol and Surface Properties (GRASP) is applied to airborne and laborat...
| Main Authors: | , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2017-03-01
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| Series: | Atmospheric Measurement Techniques |
| Online Access: | http://www.atmos-meas-tech.net/10/811/2017/amt-10-811-2017.pdf |
| Summary: | A method for the retrieval of aerosol optical and microphysical properties
from in situ light-scattering measurements is presented and the results are
compared with existing measurement techniques. The Generalized Retrieval of
Aerosol and Surface Properties (GRASP) is applied to airborne and laboratory
measurements made by a novel polar nephelometer. This instrument, the
Polarized Imaging Nephelometer (PI-Neph), is capable of making high-accuracy
field measurements of phase function and degree of linear polarization, at
three visible wavelengths, over a wide angular range of 3 to
177°. The resulting retrieval produces particle size
distributions (PSDs) that agree, within experimental error, with
measurements made by commercial optical particle counters (OPCs).
Additionally, the retrieved real part of the refractive index is generally
found to be within the predicted error of 0.02 from the expected values for
three species of humidified salt particles, with a refractive index that is well
established. The airborne measurements used in this work were made aboard the
NASA DC-8 aircraft during the Studies of Emissions and Atmospheric
Composition, Clouds and Climate Coupling by Regional Surveys
(SEAC<sup>4</sup>RS) field campaign, and the inversion of this data
represents the first aerosol retrievals of airborne polar nephelometer data.
The results provide confidence in the real refractive index product, as well
as in the retrieval's ability to accurately determine PSD, without
assumptions about refractive index that are required by the majority of OPCs. |
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| ISSN: | 1867-1381 1867-8548 |