9634125 Stith A one month field experiment will be carried out to study the formation of nitrogen oxides (NOx) by lightning and the transport of air and trace gases by thunderstorms, as a part of the Stratosphere Troposphere Experiments: Radiation, Aerosols, and Ozone (STERAO) experiment in June and July of 1996. The main facilities of STERAO are the NCAR WB57F high altitude aircraft, the NOAA WP3D aircraft with a tail Doppler radar, and the Colorado State University CHILL multiparameter Doppler radar. Both of these aircraft will collect aerosol, trace gas and kinematic data on thunderstorms. However, neither of the two aircraft are able to penetrate the upper portions of the anvil cloud from thunderstorms. This project will add the University of North Dakota Citation fanjet aircraft to STERAO, so that penetrations of anvil clouds can be made during the project. These are thought to be a critical part of the experiment, because previous measurements of NOx in thunderstorms found that a significant portion of the NOx produced by lightning was in the upper portion of the anvil cloud and not in the clear air around the cloud which will be the region sampled by the WB57F. If the same holds true for thunderstorms in STERAO, the lack of an anvil penetrating aircraft may render calculations of the NOx production by lightning difficult or impossible. The Citation will carry wind and turbulence instrumentation, trace gas instruments, and cloud microphysical probes. In particular, a fast-response chemiluminescence-based instrument for NOx measurements will be used. The experimental data along with storm kinematic data from the radars will be used to study the storm features that are responsible for the transport and redistribution of trace gases. These results will also be compared with proposed numerical cloud modeling studies of convective redistribution.
