TOPAZ Data

August 1, 2016

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Daily Summary:

Monday, August 1: CABOTS IOP2
Day 15 of CABOTS IOP 2 observations. TOPAZ data were taken from 08:42 to 19:18 PDT. Not quite as hot as the last couple of days with an offical high of 38C (100F) at the airport met tower. Cloud-free overhead all day, some Cu clouds over the Sierra crest. Very hazy in the morning with improving visibility in the afternoon, but the Sierra foothills were invisible all day. South-southeasterly surface winds thru mid-afternoon, veering to the west and becoming weaker in the late afternoon. Surface and BL ozone values stayed fairly low all day, peaking in the low 60s ppbv* around midday, decreasing during the afternoon, and then rising again into the low 60s ppbv* around 1830 PDT. TOPAZ data show a complex layered structure aloft with a thin, clean layer between 800 and 1200 m AGL, a 300 m-thick layer containing 65 ppbv of ozone and moderately high aersool concentrations up to 1500 m AGL, and above that a very clean layer with ozone mixing ratios as low as 30 ppbv up to about 2500 m AGL. These three layers were descending rapidly after 1300 PDT and it appeared that the lower two were entrained into the BL in the afternoon. Between 3 and 4 km AGL, TOPAZ detected a layer containing moderate aerosol and ozone concentrations, and a high ozone layer (75 - 90 ppbv) with low aerosol concentrations above 5 km AGL, similar to the day before.