Calendar Event Details
AEROCENTER: Reed Espinosa
Affiliation: UMBC
Event Date: Tuesday, October 4, 2016
Location: G133
Time: 11:00 AM
Retrievals of Aerosol Properties from Imaging Polar Nephelometer Scattering Measurements Using the GRASP Software Package
Aerosols and their interaction with clouds play a key role in earth’s climate. Despite the importance of these particles, accurate in situ measurements of their optical and microphysical properties remain a significant challenge. This work presents a new method for aerosol characterization based on the inversion of in situ light scattering data. 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 degrees. The resulting retrieval produces particle size distributions (PSD) that agree, to within experimental error, with measurements made by commercial optical particle counters (OPC). 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 salts particles, whose refractive index 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 (SEAC4RS) field campaign, and the inversion of this data represent the first aerosol retrievals of airborne polar nephelometer data. The results provide confidence in the 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. Lastly, the advantages and potential applications of a new Open path polar Imaging Nephelometer (OI-Neph) will be discussed.
Posted or updated: Thursday, September 22, 2016
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