CABOTS 2016 TOPAZ Data
June 12, 2016
Sunday, June 12: CABOTS IOP1
Day 15 of CABOTS IOP 1 observations. TOPAZ data were taken from 11:11 PDT on Sunday - 11:35 PDT on Monday. Cooler with a high of 35C and widespread clouds near 4.3 and 6.5 km. The clouds dispappered around 1900 PDT and a narrow layer of high (more than 125 ppbv) ozone consistent with a stratospheric intrusion appeared near 8 km agl around midnight and sloped downward to about 4 km agl at 11 am when it had largely disappeared. (Note that the vertical scale in the curtain plots extends to 7 km). The aerosol backscatter was generally very low in the descending air, consistent with a lower stratospehric origin, but with layers of weakly enhanced backscatter suggestive some entrained pollution. The BL Ozone reached about 1.4 km on Sunday afternoon and surface ozone reached about 65 ppbv with a few periods of higher (75 ppbv) concentrations in the lowest lidar measurements. The BL collapsed during the evening, but air with higher backscatter and less than 50 ppbv of ozone appeared in the lowest 500 m when the southerly synoptic flow aloft caused the surface winds to shift to the south before midnight. The BL increased to nearly 800 m by 1100 PDT on Monday, mixing ozone from aloft to the surface. An elevated aerosol layer was present between 2 and 3 km from Sunday afternoon through the early morning, converging with a lower, higher backscatter layer with high ozone that appeared to rise upward during the night.
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