TOPAZ Data

July 18, 2016

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Daily Summary:

Monday, July 18: CABOTS IOP2
Day 1 of CABOTS IOP 2 observations. TOPAZ data were taken from 08:05 to 21:01 PDT. High of about 35C with weak winds.Clear all day with decent visibility; the Sierra's were fairly sharp. A narrow layer of elevated backscatter was observed near 1800 m in the morning, gradually descending to nearly 800 m in the late afternoon before disappearing at about 19:30 PDT. A more diffuse layer of elevated (65-75 ppbv) ozone coincided with the enhanced aerosol. HYSPLIT trajectories suggest that this layer was advected inland from the Pacific. The ozone data suggest that the descending layer may have reached the top of the CBL, which the wind profiler placed at 500-800 m. However, surface ozone remained fairly low with a broad maximum of about 45 ppbv giving no indication of entrainment from aloft. This tentative conclusion is also supported by the aerosol backscatter measurements, which show that the transport layer remained sharply distinct from the boundary layer aerosol.