Thursday, May 18
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TOPAZ data were taken from 09:37 - 21:13 PDT. The data gap from about 11:00 - 14:00 PDT was due to an extensive laser system realignment. Cool temperatures throughout the day, low clouds and strong winds from a NE/NW direction in the afternoon and early evening. Due to the clouds and strong winds, surface and boundary layer ozone dropped to below 40 ppbv in the afternoon. High ozone (80 - 120 ppbv) aloft descended during the day to about 2 km AGL, but did not reach the surface.