Wednesday, May 31
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TOPAZ data were recorded from 7:34 PDT through the night until 7:02 PDT on June 1 (data collection was continued the next day without interruption). Slight cooldown compared to the day before (35 C max), light winds early, increasing to 15 m/s in the afternoon and becoming light again after sunset. Mid- and high-level clouds associated with the West Coast trough, clearing out in the early morning hours the next day. Between 11 and 12 PDT, a sudden increase in ozone by about 10 ppbv at the surface and throughout the BL (up to 1.5 km AGL) was observed. This bumpup in ozone was likely associated with the advection of air in sourtherly flow aloft that was influenced by fires burning in western Mexico. This was corroborated by the insitu observations at Angel Peak (enhanced NOx, NOy, CO, CO2, and CH4, but no increase in O3) and backtrajectory calculations. The BL rose to about 3.5 km AGL in the late afternoon. TOPAZ observed a persistent ozone layer (75 - 85 ppbv) above 4 km AGL.