613 Seminar by Dr. Meloë Kacenelenbogen (Ames)



Identifying Chemical Aerosol Signatures using Optical Suborbital Observations: How much can optical properties tell us about composition?

Aerosol speciation in chemical transport models needs to be improved using observational constraints. Atmospheric aerosol composition is typically determined using in situ instrumentation. Although some composition instruments operate on aircraft, widespread aerosol speciation measurements are not available above the planetary boundary layer and only available from surface networks. This study investigates the retrieval of aerosol chemical composition information from aerosol optical properties. We first prescribe a few source-based Air Mass aerosol Types (AMTs) using mostly airborne gas-phase measurements during SEAC4RS. We confirm that these AMTs have unique aerosol optical and chemical properties.  We then assess the ability of airborne passive aerosol optical properties to capture these AMTs and define which subset of available passive in situ retrieved optical properties is the most useful in capturing them. We find distinct chemical and optical signatures for agricultural and wildfire biomass burning, biogenic and dust AMTs. We then use these aerosol optical properties and the pre-Specified Clustering and Mahalanobis Classification method to derive optical-based AMTs during SEAC4RS. The results in this study show that a few AMTs, prescribed using mostly gas measurements, can be successfully extracted from a combination of aerosol optical properties over the US. This technique may enable widespread retrieval of dominant aerosol species using existing and future remote sensing instruments/networks. Ultimately, it has the potential to provide a much broader observational aerosol data set to evaluate global transport models than is currently available by direct in situ measurements. 

Bio: Meloë Kacenelenbogen is a research scientist at NASA Ames Research Center (ARC). She obtained her PhD in 2008 (LOA, France). Since then, she has spent many years studying the optical remote sensing observation of fine suspended particles (aerosols) in the atmosphere from ground-based, airborne and space-borne passive and active instruments. Her expertise is mostly in the characterization of aerosol type, amount, vertical distribution and direct radiative effects. She is currently part of the NASA ARC Sunphotometer/ Satellite team (https://airbornescience.nasa.gov/sunsat), which flies airborne sunphotometers to characterize aerosols, clouds and gas constituents. She is also currently a member of the AtmOS science and application transition team, which helps define the science objectives for the Aerosol Clouds, Convection and Precipitation (ACCP) Designated Observable (https://science.nasa.gov/earth-science/decadal-accp).

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613 Seminar Series Coordinators 
Reed.Espinosa@nasa.gov 
Jie.Gong@nasa.gov