Four extended observational campaigns were conducted during August and November 1988 with an ST (stratosphere–troposphere) radar in southern Australia during the passage of cold fronts over the system, giving around 30 days of three-dimensional wind measurements with 15-min time and 0.5-km height resolution over the 2–11.5-km height range. Order of magnitude increases in the variance of time-fluctuating wind velocities were measured during frontal passages, which are definitively ascribed to gravity waves. The time–height morphology of the horizontal- and vertical-velocity fluctuations differed. Bursts of horizontal-velocity variance u′2 + υ′2 ∼ 10–100 m2 s−2 arose at upper levels about a day before the frontal boundary arrived, and this activity gradually extended to lower heights as the front neared. The arrival of the frontal boundary marked a sudden reduction in this activity. After the frontal boundary passed, reduced activity persisted for ∼ 12 hours, after which bursts in u′2 + υ′2 returne... Abstract Four extended observational campaigns were conducted during August and November 1988 with an ST (stratosphere–troposphere) radar in southern Australia during the passage of cold fronts over the system, giving around 30 days of three-dimensional wind measurements with 15-min time and 0.5-km height resolution over the 2–11.5-km height range. Order of magnitude increases in the variance of time-fluctuating wind velocities were measured during frontal passages, which are definitively ascribed to gravity waves. The time–height morphology of the horizontal- and vertical-velocity fluctuations differed. Bursts of horizontal-velocity variance u′2 + υ′2 ∼ 10–100 m2 s−2 arose at upper levels about a day before the frontal boundary arrived, and this activity gradually extended to lower heights as the front neared. The arrival of the frontal boundary marked a sudden reduction in this activity. After the frontal boundary passed, reduced activity persisted for ∼ 12 hours, after which bursts in u′2 + υ′2 returne...