Atmospheric Chemistry and Physics (Nov 2010)

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

  • G. A. Morris,
  • A. M. Thompson,
  • K. E. Pickering,
  • S. Chen,
  • E. J. Bucsela,
  • P. A. Kucera

DOI
https://doi.org/10.5194/acp-10-11189-2010
Journal volume & issue
Vol. 10, no. 22
pp. 11189 – 11208

Abstract

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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) &times; 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 &times; 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.