Aircraft Observations of Aerosols, O sub(3) and NO sub(y) in a Nighttime Urban Plume

• Published in: Atmospheric environment (1994) Vol. 35; no. 13; pp. 2395 - 2404
• Main Authors: Berkowitz, Carl M, Zaveri, Rahul A, Bian, Xindi, Zhong, Shiyuan, Disselkamp, Robert S, Laulainen, Nels S, Chapman, Elaine G
• Format: Journal Article
• Language: English
• Published: 01.01.2001
• Subjects: USA, Oregon, Portland; Portland, Oregon
• ISSN: 1352-2310

On the evening of September 1 and early morning of September 2, 1998, two aircraft flights were conducted downwind of Portland, OR, and air chemistry observations were made. Results are presented in terms of aerosol concentrations, ozone, and reactive nitrogen compounds (NO sub(y)). During the flights, a surface thermal low extended inland from Medford to Portland, with an anticyclonic system building from the southwest. During the night, positive correlations were noted between O sub(3), relative humidity, NO sub(y), and aerosol number density, but in the early morning, the O sub(3) mixing ratios were anti-correlated significantly with the other parameters. Two sets of hypotheses are presented to explain the anti-correlation, involving homogeneous and heterogeneous gas-phase chemistry.