Measurement report: In situ observations of deep convection without lightning during the tropical cyclone Florence 2018

Abstract

Abstract. Hurricane Florence was the sixth named storm in the Atlantic hurricane season 2018. It caused dozens of deaths and major economic damage. In this study, we present in situ observations of trace gases within tropical storm Florence on September 2, 2018 after it had developed a rotating nature, and of a tropical wave observed close to the African continent on August 29, 2018 as part of the research campaign CAFE Africa (Chemistry of the Atmosphere – Field Experiment in Africa) with the HALO (High Altitude Long Range) research aircraft. We show the impact of deep convection on atmospheric composition by measurements of the trace gases nitric oxide (NO), ozone (O3), carbon monoxide (CO), hydrogen peroxide (H2O2), dimethyl sulfide (DMS) and methyl iodide (CH3I), and by the help of color enhanced infrared satellite imagery taken by GOES-16. While both systems, the tropical wave and the tropical storm, are deeply convective, we only find evidence for lightning in the tropical wave using both in situ NO measurements and data from the World Wide Lightning Location Network (WWLLN).

Modification of a conventional photolytic converter for improving aircraft measurements of NO<sub>2</sub> via chemiluminescence

“…NO concentrations varied between 0.005 and 0.56 ppbv for MF10 and between 0.005 and 0.46 ppbv for MF12. We have recently shown that enhanced NO concentrations in the morning and afternoon of MF12 were due to local, recent light- ning activity (Nussbaumer et al, 2021). For MF10, enhanced NO concentrations at high altitudes had their source over the African continent.…”

New photolytic converter for improving aircraft measurements of NO<sub>2</sub> via chemiluminescence

“…NO concentrations varied between 0.005 and 0.56 ppbv for MF10 and between 0.005 and 0.46 ppbv for MF12. We have recently shown that enhanced NO concentrations in the morning and afternoon of MF12 were due to local, recent lightning activity (Nussbaumer et al, 2021). For MF10, enhanced NO concentrations at high altitudes had their source over the African continent.…”