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Atmospheric Odd Nitrogen (AON) Group
AON Group Members:
As of August, 2006, the AON Group is now part of the Community Airborne Research (CARI) Group Summary of Activities:
The group participated in the Terrain-Induced Rotor Experiment (T-REX) with airborne measurements of O 3 in waves in the lee of the Sierra Nevada range in California . The primary objective of T-REX was to study the structure and evolution of intense low-level horizontal vortices (rotors) over the Owens Valley immediately downstream of the mountain range. These waves have chemical implications as well as dynamical. Wave-breaking can lead to turbulence and mixing of chemical constituents among different layers of the atmosphere. In particular, they may promote mixing across the tropopause region and so contribute to bi-directional stratosphere-troposphere exchange. Our instrument was deployed on NCAR's new G5 (HIAPER) aircraft. The instrument package included a previously flow detection unit and some components designed and certified as part of the HAIS O 3 instrument development, which will result in a requestable resource for outside investigators.
The figure shows data obtained in a wave during T-REX. The tropopause region is one of steep vertical gradients in mixing ratios. As a result, the vertical wave motions lead to a pronounced wave structure when sampled by a horizontally-flying aircraft, as evident in the figure. Air that is displaced upward brings low-O 3 air up from below, while downward moving air brings O 3 -rich air from above. Water and CO have vertical gradients opposite in sign from O 3 , so they vary together in a manner opposite to O 3 .
The group also participated in MIRAGE/IMPEX with measurements of NO, NO 2 , NO y , and O 3 from the C130. The existing 4-channel WB57 instrument was re-configured for installation on the C130, with the incorporation of new capabilities for O 3 and NO 2 , along with NO and NO y channels, as well as adaptation to a new inlet location.
The new photolytic converter appears to have worked well, as did the new modular data acquisition system and power supply, compatible with those for the group's HIAPER instruments. A lot of interesting data were obtained in these two-dozen-plus flights and analysis is just beginning. In conjunction with the measurement of PANs , we will first take a look at the partitioning of NO y in the various air-mass types sampled in MIRAGE and IMPEX.
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