Abstract for Kudeki and Riggin proposals ATM 9709251 & ATM 9709030 The investigators will conduct a series of experiments using two radars located at Jicamarca near Lima, Peru, to study the gravity wave dynamics in the tropical middle atmosphere over a three-year time span. The objective is to study the processes that produce the saturated wave spectrum in the stratosphere and mesosphere from long periods to the shortest buoyancy waves. One of the radars is a mesosphere-stratosphere-troposphere radar and the other is called JULIA a subsystem of the large 50 MHz Jicamarca incoherent scatter radar. JULIA will be operated continuously for an entire month to measure stratospheric winds. The larger Jicamarca system will operate for a five-day campaign within the month to measure winds over a wider range of heights. Preliminary evidence from recent experimental campaigns at Jicamarca suggest the presence of isolated wave packets. The new experiments will allow the investigators to assess the contribution of these isolated wave packs to the overall wave spectrum. Other recent experiments suggest that inertia-gravity waves with periods of 1-3 days may transport much of the momentum that drives the quasi-biennial oscillation in the tropical stratosphere. The 24-hour coverage of the JULIA radar will allow more comprehensive analysis of the low-frequency waves and a more accurate determination of their intrinsic wave parameters to provide guidance for large-scale models of the middle atmosphere. This is a joint effort involving the University of Illinois and Northwest Research Associates. The University of Illinois investigators will be responsible for experiment planning and data acquisition and analysis, while Northwest Research Associates will be responsible for modeling the implications on middle atmospheric dynamics.
