Ozone Concentrations, Fluctuations, and Related Atmospheric Chemistry Pertaining to the Lake Tahoe Basin

During the summer of 2012, air quality data were collected at four different sites within the Lake Tahoe Basin.  Two of the sites were located at the Homewood Mountain Resort on the western side of Lake Tahoe (1921 m and 2399 m above sea level) while the other two sites were located on the southeastern side of the lake (Heavenly Mountain Resort in South Lake Tahoe, CA, at 2615 m above sea level, and the Tahoe Regional Planning Agency (TRPA) headquarters in Stateline, NV, at 1939 m above sea level).  All four sites experienced similar midday ozone maxima of approximately 55 parts per billion (ppbv).  Most of this ozone was attributed to air parcels traveling into the basin from the Sacramento Valley.  Nitrogen oxide concentrations were very low at three of the measurement sites, but one site (TRPA) displayed sufficiently high concentrations of NO and NO₂ that it might occasionally be considered NOx (nitrogen oxide) saturated.  Therefore, while an increase in nitrogen oxides concentrations would be expected to increase ambient ozone at most areas around the Lake Tahoe basin, the opposite could be true near the TRPA site.