In January 1993 an extensive set of radar and optical data was gathered from various key sites around the world during a coordinated ''10 Day Run'' designed to investigate the coupled dynamic behavior of the upper atmosphere on a large, medium and small scale. As part of this campaign an all-sky CCD imaging system was operated at Arecibo Observatory, Puerto Rico, to help quantify the response of the low latitude mesosphere-thermosphere system to short period (<1 hour) gravity waves. Measurements of the OI(557.7 nm) and near infrared OH nightglow emissions were made in conjunction with photometric and ISR radar soundings and revealed an abundance of small-scale structure in the 80--100 km range. In this letter we apply two-dimensional spectral analysis techniques to aid in the interpretation of a complex set of image data that consisted of two intersecting quasi-monochromatic gravity wave patterns progressing on approximately orthogonal headings. An investigation of the spectral content and temporal evolution of these wave motions at each emission altitude is presented. ¿ American Geophysical Union 1995.