AAAR 32nd Annual Conference
September 30 - October 4, 2013
Oregon Convention Center
Portland, Oregon, USA
Abstract View
Mixing of Biogenic Emissions with Urban Plume: A Case Study from CARES
NOOPUR SHARMA, Swarup China, Manvendra Dubey, Kyle Gorkowski, Bradley Flowers, Madhu Gyawali, W. Patrick Arnott, Rahul Zaveri, Arthur J. Sedlacek, R. Subramanian, Claudio Mazzoleni, Michigan Technological University
Abstract Number: 439 Working Group: Carbonaceous Aerosols in the Atmosphere
Abstract Single particle analysis can provide detailed characterization of morphology and mixing states of atmospheric aerosol particles and facilitate a better understanding of sources, transport and processing in the atmosphere. The Carbonaceous Aerosol and Radiative Effects Study (CARES) took place in the Sacramento urban area, California in June 2010 to study urban aerosols, their transport, aging and mixing with other atmospheric aerosols. Metrological data show that the measurement sites during the field campaign were dominated by South Westerly (SW) winds which were favorable for transporting the plume from the urban site of Sacramento (T0) to the T1 site located in Cool, a small town 40-km East of T0 in a forested area at the foothills of the Sierra Nevada. During such SW transport events, particles emitted in the Sacramento area mixed with local biogenic particles abundant at T1. In contrast, during NW transport events the urban plume was transported to the Southeast without significantly impacting T1.
In this study we investigate the variations in aerosol optical and morphological properties during the SW transport periods versus NW transport periods. Aerosol samples were collected on nuclepore filters during the campaign for electron microscopy analysis of single particles. For the detailed single particle analysis, we selected two days: 1) June 21, 2010 with NW wind patterns, and 2) June 25, 2010 with SW wind patterns. We analyzed morphology and mixing states of using a scanning electron microscopy. A single particle soot photometer was used to study the black carbon mass concentration and mixing state. The aerosol light scattering and absorption at three wavelengths were studied using a photoacoustic spectrometer. We will present the results of the analysis on biogenic aerosol morphology, mixing state and optical properties with and without influence of the urban plume.