TOPAZ Data

July 27, 2016

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Daily Summary:

Wednesday, July 27: CABOTS IOP2
Day 10 of CABOTS IOP 2 observations. TOPAZ data were taken from 11:22 to 19:46 PDT. The measurements overlapped with the Fresno-Visalia transects by the SA Mooney in the afternoon. The TARDIS Doppler lidar was also set up today to measure vertical velocities; this system confirmed the 600 m CBL depth determined from the TOPAZ aerosol profiles and radar wind profiler. Very hot again with an offical high of 41C (106F) at the airport tower between 1705 and 1740 PDT. Cloud-free overhead all day, but significant FWC above the Sierra. Very hazy, with the mountains totally obscured from view all day. The lidar backscatter reached unprecedented levels. Typical southeasterly surface winds in the morning, veering to the northwest and becoming weaker in the afternoon. The CBL remained very shallow (about 600 m), with SE-to-SW winds in the morning and west-northwesterly in the afternoon. Northwesterly to northerly winds above 1 km all day. Surface ozone peaked at about 110 ppbv* around 1400 PDT. Did I say it was hot? TOPAZ found extremely high aerosol backscatter and ozone (100-120 ppbv) in the CBL and up to about 1500 m (aged smoke?). Much cleaner air temporarily appeared above the CBL after 1700 PDT, when the winds shifted to the north. Both ozone and aerosol backscatter in the BL slowly diminished after 1800 PDT.