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

• Main Authors: G. A. Morris, A. M. Thompson, K. E. Pickering, S. Chen, E. J. Bucsela, P. A. Kucera
• Format: Article
• Language: English
• Published: Copernicus Publications 2010-11-01
• Series: Atmospheric Chemistry and Physics
• Online Access: http://www.atmos-chem-phys.net/10/11189/2010/acp-10-11189-2010.pdf

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. NO<sub>2</sub> data from the Ozone Monitoring Instrument (OMI) show enhancements, suggesting lightning production of NO<sub>x</sub>. 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 (O<sub>3</sub>) 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) × 10<sup>6</sup> moles of O<sub>3</sub>. This estimate agrees to within a factor of two of our estimates of photochemical lightning O<sub>3</sub> production from the WWLLN flashes, from the radar-inferred lightning flash data, and from the OMI NO<sub>2</sub> data (~1.2, ~1.0, and ~1.7 × 10<sup>6</sup> moles, respectively), though all estimates have large uncertainties. Examination of DC-8 in situ and lidar O<sub>3</sub> data gathered around the Gulf that day suggests 70–97% of the O<sub>3</sub> change occurred in 2.5–5.1 km layer. A photochemical box model initialized with nearby TC4 aircraft trace gas data suggests these O<sub>3</sub> production rates are possible with our present understanding of photochemistry.