Evidence of convection as a major source of condensation nuclei in the northern midlatitude upper troposphere

• Main Authors: Wang, Y, Liu, SC, Anderson, BE, Kondo, Y, Gregory, GL, Sachse, GW, Vay, SA, Blake, DR, Singh, HB, Thompson, AM
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: eScholarship, University of California 2000
• Subjects: Meteorology & Atmospheric Sciences; North Atlantic
• Online Access: https://escholarship.org/uc/item/9p2286ng

We examine concurrent measurements of CN (size > 8 nm), NO, and NO(y) in the upper troposphere over the North Atlantic during the SONEX Experiment (Oct.-Nov., 1997). High CN and NO(y) observations are attributed largely to the enhancement in convective outflow. Using the ratio of NO/NO(y) as a chemical clock, we estimate that dilution of convective high-CN plumes is rapid (on a time scale of <2 days) and accounts for a large fraction of elevated CN concentrations above the background. We estimate that less than 7% of observed high-CN (> 10000 cm−3) plumes may be attributed to aircraft emissions. The contribution by aircraft emissions to upper tropospheric CN concentrations is estimated to be significantly higher than 7% because aircraft plumes dilute much faster than convective plumes and hence are sampled less frequently.