Convective Transport of Trace Gases from Near the Surface to the Upper Troposphere - a Case Study
Abstract:Deep convection transports chemically reactive trace gases from near the Earth’s surface to the upper troposphere (UT). Short-lived compounds which are usually only present close to their sources on the ground are rapidly injected into the upper troposphere where they alter the chemical equilibria typical of that region of the Earth’s atmosphere. One important consequence is, for example, the formation of ozone which acts as a greenhouse gas in the UT.
NASA’s SEAC4RS mission took advantage of the heavily instrumented DC-8 aircraft to study convective events in the South Eastern and South Central US. Here we will show a detailed experimental and modeling analysis of a convective event sampled on September 11, 2013 over Arkansas. Insoluble species such as isoprene were strongly elevated in the UT while soluble species had been removed by strong precipitation. Ozone was formed in the presence of lightning NOx. The textbook-like example is shown to discuss chemical and physical processes affecting trace gas composition in a convective updraft event.