[1] On 3 and 5 September 2002 the OH all-sky imager at Platteville, Colorado (40.2°N, 104.7°W), observed small-scale, wavelike patterns (known as ripples), with horizontal wavelengths of $9 km and $7 km and lifetimes of $9 min and $15 min, respectively. The Colorado State University sodium lidar at nearby Fort Collins, Colorado (40.6°N, 105°W), also made concurrent observations of temperature and zonal and meridional winds, which allowed us to determine the nature of the ripples observed. Our observations suggest that the 3 September ripple was induced by a convective instability located at 87.5 km and the 5 September ripple was induced by a dynamic instability at 88.5 km. The ripples clearly advected as packets with the background wind. Lidar measurements also allowed us to relate the directions of wind shear to the phase front alignments of both the ripples and the nearby short-period atmospheric gravity waves. These spatial relationships provided a meaningful comparison with previously observed ripples as well as with current theoretical models. Using the 16-hour continuous lidar data set for each case, we deduced that long-period waves created an unusually large temperature perturbation at the ripple times on 3 September and an unusually large wind shear perturbation on 5 September. These perturbations prepared the background atmosphere to be near the verge of local instability, but, as revealed again by lidar observation, it was the superposition of smaller-scale perturbations at the time of the ripples that helped to actually reach the conditions required for instability and generation of the ripples.

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Ground-based optical instrumentation supported the AIDA '89 wind measurement comparisons by describing the gravity waves affecting the 8@ 100 km altitude region during clear dark hours over Puerto Rico. This study tabulates the characteristics of gravity waves with fractional column emission rate amplitudes up to 30% and with periods greater than 45 min as seen in the O2 airglow layer by MORTI. a sensor of 0, rotational temperature and column emission rate in twelve look directions. Data from seven other sensors operating at Guanica and the Arecibo Observatory are then compared with the MORTI data to check the consistency of the entire data set with the wave parameters, primarily velocities, deduced from MORTI. Nine nights of visually distinct crests and troughs were found, one of which was dominated by an evanescent wave and the rest by internal waves. The nights of 5/6 April and 4/5 May 1989 were selected for multi-sensor comparisons. The comparisons showed substantial agreement between the MORTI characterizations and the observations by others, and most differences were attributed to complexities introduced by higher frequency components with shorter coherence distances. Nightly summaries of the 0, rotational temperature and column emission rate are also given.

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