Surface NOx Measurements in Northern Alabama During and After DC3

A residual gas nitrogen oxides (NOx) analyzer was employed for the purpose of measuring surface NOx in Huntsville, Alabama during the Deep Convective Clouds and Chemistry (DC3) campaign. Measurements were taken during a variety of conditions, including storm-free days and nights, non-thunderstorm outflow, and several thunderstorm outflows. In addition to the regular diurnal cycle in NOx caused by local anthropogenic activity, thunderstorm outflows produced small but measurable increases in surface NOx. The magnitude of NOx increase is supportive of the "backwards C" model profile of lightning NOx.