A 3-year study of gravity wave variability covering 1991, 1992, and 1993 was conducted using horizontal wind measurements collected by a partial reflection MF radar located on the island of Kauai, Hawaii (22 N, 160 W). High echo return rates between 70 and 98 km provided ample time resolution for the study of gravity wave variability in this height range. Horizontal wind measurements were band pass filtered for periods between 20 min and 6 hours, establishing a gravity wave band time series. Gravity wave variance and polarization calculations were carried out over various time frames and examined with regard to their response to season and background environment. Among the more interesting observed phenomena were the annual and semiannual oscillations in the gravity wave variances, a significant diurnal and semidiurnal variability in the variances, and an extended enhancement of these variances during the latter half of 1992 and the beginning of 1993. ¿ American Geophysical Union 1996