HIGH-RESOLUTION HORIZONTAL WAVE-NUMBER SPECTRA OF MESOSPHERIC WAVE PERTURBATIONS OBSERVED DURING THE 21 OCTOBER TRIANGULAR FLIGHT OF ALOHA-93

On 21 October 1993 during ALOHA-93 the NCAR Electra flew a triangular path to the northwest of Maui. To improve the horizontal resolution of the Na lidar and OH imager, the aircraft cruising speed was reduced t o an average of similar to 135 m/s. The lidar and imager observations are used to study the high horizontal wave number (k) region of mesosp heric wave perturbation spectra. The relative atmospheric density spec trum inferred from the Na lidar data is well approximated by the k(-1. 3) power-law over the complete wave number range from k = 2 pi/(400 km ) to 2 pi/(2 km). The observed spectrum shows no evidence of the index change near k = m predicted by the separable gravity wave model of G ardner et al. [1993], where m is the characteristic vertical wave num ber. The OH intensity spectra computed across and along the flight tra ck, as well as the Na abundance spectrum, are inconsistent with both t he separable gravity wave model [Gardner et al., 1993] and scale-indep endent diffusive filtering theory [Gardner, 1994]. Existing models of Na abundance and OH intensity fluctuations are based on linear perturb ation theory and may not be valid because they do not include nonlinea r effects.