Observations of ozone production in a dissipating tropical convective cell during TC4

From 13 July-9 August 2007, 25 ozonesondes were launched from Las Tablas, Panama as part of the Tropical Composition, Cloud, and Climate Coupling (TC4) mission. On 5 August, a strong convective cell formed in the Gulf of Panama. World Wide Lightning Location Network (WWLLN) data indicated 563 flashes (09:00-17:00 UTC) in the Gulf. NO₂ data from the Ozone Monitoring Instrument (OMI) show enhancements, suggesting lightning production of NO _x. At 15:05 UTC, an ozonesonde ascended into the southern edge of the now dissipating convective cell as it moved west across the Azuero Peninsula. The balloon oscillated from 2.5-5.1 km five times (15:12-17:00 UTC), providing a unique examination of ozone (O₃) photochemistry on the edge of a convective cell. Ozone increased at a rate of ∼1.6-4.6 ppbv/hr between the first and last ascent, resulting cell wide in an increase of ∼(2.1-2.5) × 10⁶ moles of O₃. This estimate agrees to within a factor of two of our estimates of photochemical lightning O₃ production from the WWLLN flashes, from the radar-inferred lightning flash data, and from the OMI NO₂ data (∼1.2, ∼1.0, and ∼1.7 × 10⁶ moles, respectively), though all estimates have large uncertainties. Examination of DC-8 in situ and lidar O₃ data gathered around the Gulf that day suggests 70-97% of the O₃ change occurred in 2.5-5.1 km layer. A photochemical box model initialized with nearby TC4 aircraft trace gas data suggests these O₃ production rates are possible with our present understanding of photochemistry.