Wednesday, 14 January 2009: 9:45 AM
NOx Production by Laboratory Simulated TLEs
Room 126A (Phoenix Convention Center)
This research examines nitrogen oxides (NOx) produced in the middle atmosphere by transient luminous events (TLEs), which is transported to the polar stratosphere via the global meridional circulation and downward diffusion. A pressure-controlled vacuum chamber was used to simulate middle atmosphere pressures, while a power supply and in-chamber electrodes were used to simulate TLEs in the pressure controlled environment. Chemiluminescence NOx analyzers were used to sample NOx produced by the chamber discharges. Total NOx production for each discharge as well as NOx per ampere of current and NOx per Joule of discharge energy were plotted. Absolute NOx production was greatest for discharge environments with upper tropospheric pressures (100-380 torr), while NOx/J was greatest for discharge environments with stratospheric pressures (around 10 torr). The different production efficiencies in NOx/J as a function of pressure pointed to three different production regimes, each with its own reaction mechanisms: one for tropospheric pressures, one for stratospheric pressures, and one for upper stratospheric to mesospheric pressures (no greater than 1 torr). Using global lightning frequency as a proxy for sprite frequency, global annual average sprite NOx production was determined to be between 3.06x10^25 and 1.56x10^28 molecules per second.