CABOTS 2016 TOPAZ Data
July 24, 2016
Sunday, July 24: CABOTS IOP2
Day 7 of CABOTS IOP 2 observations. TOPAZ data were taken from 09:46 to 00:58 PDT. The SA Mooney made 4 missed approaches in the early afternoon and evening and 2 missed approaches with one spiral profile to 3 km soon after midnight. The sky was cloud-free all day, but with poor visibility in the morning. Very hot with a high of 41C (106F) at the airport tower around 1800 PDT. Southeasterly surface winds in the morning, veering to the southwest in the mid-afternoon, and then becoming much weaker in the evening. Surface ozone peaked at about 80 ppbv* near 1500 PDT, decreased to 60 ppbv, then fell rapidly after 1900 PDT when the winds dropped. Lack of wind allowed surface ozone to be almmost completely titrated by traffic on CA-99 around midnight, much earlier than usual. The profiler winds were westerly up to about 1000 m in the early afternoon, and rotated to the north in the late afternoon and evening. The profiler showed the CBL to be less than 800 m deep. The lidar showed ozone to be relatively high (>60 ppbv) from the top of the morning BL to more than 2 km. Ozone increased to 70-80 ppbv in the CBL from about 1200 to 1600 PDT, then decreased to about 60 ppbv. The region of enhanced backscatter was shallower than the profiler CBL top. Higher ozone was also observed between 4 and 6 km. Smoke and high ozone from the Sobaranes Fire began to appear just above 2 km around 1700 PDT and was more widespread between 1 and 2 km by 1900 PDT. There was an interesting decrease in ozone around the leading edge of the diffuse plume between 1800 and 2000 PDT. Comparisons to the Mooney data when the smoke was present in the evening and night will be particular interesting.
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