TOPAZ Data

July 28, 2016

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Daily Summary:

Thursday, July 28: CABOTS IOP2
Day 11 of CABOTS IOP 2 observations. TOPAZ data were taken from 11:40 to 19:40 PDT. The measurements overlapped with the Fresno-Visalia transects by the SA Mooney and the Alpha Jet missed approach in the afternoon. The CARB audit team checked the 2B ozone monitor in the morning; the in situ measurements between about 820 and 0920 are not ambient concentrations. Very hot again with an offical high of 41C (106F) at the airport met tower at 1800 PDT. Cloud-free overhead all day with significant Cu formation above the Sierra. Very hazy, with PM2.5 concentrations near 25 ug/m3 at Visalia-Church St. throughout the afternoon. The mountains were once again totally obscured from view all day. South-southeasterly surface winds in the morning, veering to the west and becoming weaker in the afternoon. The CBL remained very shallow (about 600 m), with southwesterly flow up to about 2 km. TOPAZ found highly variable aerosol backscatter and ozone (up to about 100 ppbv) both in the CBL and in layers between the CBL and about 2000 m (aged smoke?). Another thin aerosol layer without ozone appeared around 4000 m in the late afternoon. The Mooney and the Alpha Jet made low approaches at 1528 and 1547 PDT, respectively. Surface ozone was lower than on the previous day, peaking at about 85 ppbv* near 1430 PDT.