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Patricia Sawamura Successfully Defended Her Dissertation!

August 21, 2013 9:45 AM

Patricia Sawamura, graduate student in Physics, successfully defended her dissertation entitled "Retrieval of Optical and Microphysical Properties of Aerosols from a Hybrid Lidar Dataset".   Patricia's work is also being submitted to Atmospheric Measurement Techniques.  Lidar data from the DISCOVER-AQ experiment in Baltimore and Washington DC in 2011 provided a unique opportunity to that point to attempt a retrieval of the complex index of refraction, size, number and volume distribution, and single scatter albedo of an urban aerosol, in profiles.  While these parameters are retrieved from a multiwavelength inversion of AERONET sunphotometer data, the results are an average of an entire column of aerosol.   Using three lidar wavelengths from neodymium YAG lasers, the backscatter at the three wavelengths and the extinction at 355 and 532 nanometers is sufficient to attempt such a microphysical retrieval of these aerosol properties in confined layers above the surface.  This gives the opportunity to discern different aerosol properties of aerosols which may come from different sources.   To date, such an inversion has only been attempted with Raman Lidars (mostly in Europe) and all at night.   This is the first attempt to do a daytime retrieval where the results could be compared with AERONET.

Using the NASA Langley High Spectral Resolution Lidar (HSRL) for two of the wavelengths and the UMBC ground based lidars for 355nm and a 532nm confirmation of assumptions, Patricia retrieved properties of aerosols for 13 case studies during the DISCOVER-AQ experiment.  Her results were in agreement with AERONET for most of the cases, except where the aerosol was overlying smoke or depolarizing as in dust.  She also compared her results with profiles from the NASA P3-B aircraft sampling which was done in spirals near UMBC.

The techniques she used in her thesis are now part of the instrument processing suite for the NASA Langley HSRL system and Patricia has been offered a NASA Post-Doctoral Program fellowship to continue her research at Hampton Virginia.   Patricia is a native of Brazil and did her undergraduate studies with Eduardo Landulfo of the University of Sao Paolo.  Her mentor at UMBC was Ray Hoff.