Local and Regional Influences on Aerosol Composition at two Coastal Sites during EPCAPE
SANGHEE HAN, Abigail Williams, Veronica Berta, Jeramy Dedrick, Christian Pelayo, Nattamon (Jeep) Maneenoi, Atsushi Osawa, Maria Zawadowicz, Arthur J. Sedlacek, Lynn M. Russell, Scripps/UCSD
Abstract Number: 675
Working Group: Aerosol Chemistry
Abstract
In coastal areas, aerosol composition is influenced by both local and regional emissions, with variations depending on meteorological conditions. The Eastern Pacific Cloud Aerosol Precipitation Experiment (EPCAPE) characterized aerosol composition in a coastal area using measurements at Scripps Pier (300 m Offshore and 18 m ASL) and inland at Mt. Soledad (3 km downwind and 250m ASL). This study compares the aerosol composition, focusing on the refractory black carbon (rBC) measured by Single Particle Soot Photometer (SP2), and non-refractory (NR) aerosol composition measured by high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) or aerosol chemical speciation monitor (ACSM) at each site. The hourly averaged mass concentrations of rBC and NR aerosol compositions at Mt. Soledad moderately correlate to those measured at Scripps Pier (r=0.64-0.74). The seasonal patterns and magnitudes of chemical mass concentrations were similar at both sites, indicating a consistency in aerosol sources. During summer, low concentrations of rBC, NR-organics, and NR-NO3 were observed for air masses transported from the coastal northwesterly region (about 80% of the time). However, when the air masses originated from the Santa Ana or southerly directions, concentrations of rBC were up to 2.5 times higher, NR-organics were 1.3 times higher, and NR-NO3 were 1.5 times higher at both sites, bringing higher concentrations from inland San Diego. During coastal northwesterly trajectories, the concentrations of rBC, NR-organics, and NR-NO3 at Mt. Soledad were significantly higher (p < 0.05) than at Scripps Pier, likely attributed to the local impact on aerosol composition at Mt. Soledad under constant and strong sea breeze. These analyses quantify the local differences in concentrations that constrain aerosol composition and their sources in this coastal region.