Observations of inertia‐gravity wave motions in the stratosphere over Jicamarca, Peru

We present results obtained with the MST radar at Jicamarca, Peru over 10 days in January, 1993. During this campaign, inertia‐gravity waves with observed periods of ∼36 hours were seen in the stratosphere (19–30 km). The radar was operated with a high (400‐m) range resolution allowing accurate determination of wave propagation characteristics. The large variation of wave amplitude (∼2–10 ms⁻¹) with height and time suggests a superposition of several wave motions. As consistent with upward energy propagation, the phase fronts descended with time, and a vertical wavelength of ∼5 km was inferred from the rate of this phase descent. Orbital ellipses imply largely zonal propagation with an intrinsic period of roughly 30 hours, somewhat less than the observed period. The shorter intrinsic period suggests eastward wave propagation, in opposition to the predominantly westward mean motion.