FAST-LVOS 2017 TOPAZ Data

June 23, 2017

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Daily Summary:

Friday, June 23
TOPAZ data were recorded from 09:26 - 21:02 PDT. Another extremely hot day (max. of 45 C at the lidar site) and 112 F at the NLVA NWS tower. Very clear with a few scattered FWC in the late afternoon. Calm for most of the day with very light (5 m/s) NW winds before 0900 and W after 1800 PDT. There was no evidence of elevated aerosol or ozone layers from either the aged AZ and Mexican Fires, or from the Holcomb Fire aloft, and the in situ ozone concentrations remained below 65 ppbv at Angel Peak. Surface ozone at NLVA was about 40 ppbv at 0900 PDT, but increased monotonically to a peak of more than 100 ppbv aound 1600 PDT. TOPAZ found similar concentrations throughout the mixed layer, which remained less than 1500 m deep until after 1400 PDT. The ML then developed a series of short-lived 4 km deep plumes that persisted until nearly 1900 PDT, and modulated the aerosol and ozone concentrations above the surface. The ML abruptly collapsed around 1900 PDT, leading to a rapid drop in ozone from the surface to 2 km agl as the surface winds shifted to the west and increased to 5 m/s. The MDA8 calculated from the 1-min running average ozone was greater than 80 ppbv at the TOPAZ truck, and the MDA8 reached values of 77, 76, 78, and 75 at the Joe Neal, Palo Verde, Walter Johnson, and JD Smith monitoring sites, respectively.