FAST-LVOS 2017 TOPAZ Data

June 5, 2017

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Daily Summary:

Monday, June 5
TOPAZ data were recorded from 9:46 - 18:10 PDT. Hot once again with an max of 101F at the NLVA (VGT) NWS station. Clear skies with a few scattered Cu over the mountains. Strong southwesterly winds persisted throughout the night before calming between 0800 and 1200 PDT. The winds prevented surface deposition and in situ ozone remained relatively high except for a period of local titration around 0600 PDT. TOPAZ showed the high ozone associated with the streamers observed yesterday to still be present. Some of this ozone was mixed down to the surface when the ML rapidly grew around 1100 PDT, causing a short-lived increase in the surface concentrations to more than 70 ppbv. High O3/Low CO UT/LS air also descended to Angel Peak around 0300 PDT and later in the morning. The MLH was limited to 3.2 km by the stable cap of the streamer, and the deep SW flow (from the surface to the stratosphere) advected relatively clean air (50-55 ppbv) to Las Vegas beneath the streamer. This air offset any ozone increase caused by entrainment of the overlying streamer, and the in situ concentrations at NLVA dropped to 55 ppbv when the 10-15 m/s SW winds resumed at noon, and remained below 65 ppbv for the rest of the day.