Las Vegas Ozone Study (LVOS) 2013 TOPAZ Data

May 21, 2013

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Daily Summary:

May 21. Tuesday. Thick high clouds all day, but well above the lidar range. Winds were steady and from the SW all day. Lidar data was collected from 1151 to 1751 PDT. The preliminary TOPAZ curtain plot shows 60-70 ppbv O3 below 0.7 km AGL in the morning, with 50-60 ppbv above. TOPAZ measured ~65 to 75 ppbv from the surface to 3 km AGL in the afternoon. In situ O3 also gradually increased from ~60 to 75 ppbv over the data collection period while CO decreased from ~135 to 130 ppbv. Several surface stations in the valley measured 1-h averages in excess of 75 ppbv during the late afternoon. A second O3 peak was recorded to the SW of Las Vegas at Jean with a 1-h concentration of 84 ppbv at 2100 PDT (0400 UT). The MDA8 at Jean exceeded the NAAQS with 78 ppbv. The Angel Peak in situ O3/CO measurements recorded 75/125 ppbv at 2100 PDT, which suggests that the sampled air was not influenced by the Grand Fire in Southern California, but may have been transported downward from the UT/LS somewhere to the SW of Las Vegas the previous day.
Note: the low (purple) ozone values seen near the top of the curtain plot near midday are biased by the solar background in these preliminary analyses.