Vertical Distribution of Ozone and Nitric Acid Vapor on the Mammoth Mountain, Eastern Sierra Nevada, California

In August and September 1999 and 2000, concentrations of ozone (O(3)) and nitric acid vapor (HNO(3)) were monitored at an elevation gradient (2184–3325 m) on the Mammoth Mountain, eastern Sierra Nevada, California. Passive samplers were used for monitoring exposure to tropospheric O(3) and HNO(3) vapor. The 2-week average O(3) concentrations ranged between 45 and 72 ppb, while HNO(3) concentrations ranged between 0.06 and 0.52 μg/m3. Similar ranges of O(3) and HNO(3) were determined for 2 years of the study. No clear effects of elevation on concentrations of the two pollutants were detected. Concentrations of HNO(3) were low and at the background levels expected for the eastern Sierra Nevada, while the measured concentrations of O(3) were elevated. High concentrations of ozone in the study area were confirmed with an active UV absorption O(3) monitor placed at the Mammoth Mountain Peak (September 5–14, 2000, average 24-h concentration of 56 ppb).