Estimation of aerosol particle density, dynamic shape factor, and mass concentration during the Metro Manila Aerosol Characterization Experiment (MACE) 2015

Date of Award

2017

Document Type

Thesis

Degree Name

Master of Science in Atmospheric Science

Department

Physics

First Advisor

Simpas, James B., Ph.D.

Abstract

Comprehensive physical properties of particulate matter (PM) were measured at an urban background site (Manila Observatory-MO) and two roadside sites (Katipunan and Taft Avenue) during the Metro Manila Aerosol Characterization Experiment (MACE), from March to June 2015. Among the most important parameters of aerosol particles that have not been widely reported are the number size distribution and the total number concentration. These were measured by the Mobility Particle Size Spectrometer (MPSS) and the Aerodynamic Particle Sizer (APS), covering aerosol particle size ranges from 10 nm to 10 m. The combination of the measured mobility and the aerodynamic particle size distribution using an inversion algorithm provide an estimated value for the particle density and the dynamic shape factor (morphology). A closure study of the PM2.5 mass concentration from a gravimetric method and the estimated mass concentration from the total number size distribution is also presented. The atmospheric aerosol distribution in all sampling locations is characterized by three modes (nucleation, accumulation, and coarse). The ultrafine particles (<100nm) dominated the PM2.5 number concentration (Kat = 95%, MO = 91 %, and Taft = 94%) while contributing the least (Kat = 12 %, MO = 8%, Taft = 15 %) to the mass concentration. Estimated values of dynamic shape factor from the three sites (Kat = 1.59, MO = 1.43, and Taft = 1.95) suggest that roadside site aerosol is dominated by irregularly shaped (soot-like) particles. The derived effective density has an average of 1.28 g/cm3, 1.15 g/cm3 and 0.94 g/cm3 for MO, Katipunan, and Taft, respectively. The number-derived PM2.5 mass concentration is on average 17% higher than that measured using the gravimetric method. Despite the slight variation of results from the two techniques, the number-derived daily PM2.5 mass concentrations correlate reasonably well with the measured daily gravimetric mass (R2 = 0.79). The results of these comparisons build confidence in the accuracy of these real-time measurements.

Comments

The A7.C38 2017

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