CABOTS 2016 TOPAZ Data
July 31, 2016
Sunday, July 31: CABOTS IOP2
Day 14 of CABOTS IOP 2 observations. TOPAZ data were taken from 10:33 to 20:01 PDT. Hot again with an offical high of 39C (102F) at the airport met tower. Cloud-free overhead all day, Cu clouds over the Sierra crest. Less hazy with the Sierra foothills somewhat visible. Typical surface wind pattern with south-southeasterly surface winds in the morning, gradually veering to the southwest/west and becoming weaker in the afternoon. Surface and BL ozone values stayed fairly low all day, peaking at about 60 ppbv* around midday and then decreasing during the afternoon. TOPAZ data show a clean layer with very low ozone mixing ratios of 30-35 ppbv extending from about 600 up to 1500 m AGL. The BL grew to about 800 m in the early/mid adfternoon, entraining low aerosol and ozone concentrations into the BL, which likely caused the unusally low surface ozone values. Between 1430 and 1630 PDT, surface dewpoints dropped from about 13 C down to 4 - 10 C, indicating that the clean layer that overlaid the BL was also quite dry. Above 1500 m AGL, TOPAZ detected several layers with high aerosol and moderate ozone concentrations associated with the Soberanes Fire (and perhaps also the Goose Fire). Above 5 km AGL a high ozone layer (70 - 90 ppbv) with low aerosol concentrations was observed.
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