GALILEO ENTRY PROBE RECOVERY OF FINE-STRUCTURE IN THE ZONAL WIND-PROFILE AT JUPITER

The algorithm developed to recover the zonal (east-west) wind profile at Jupiter by Doppler tracking of the Galileo probe is well establishe d in theory and verified by computer simulation. We extend the Doppler wind recovery algorithm to include detection and extraction of micros cale wind structure. When the probe encounters regions of high wind sh ear, turbulence, atmospheric waves, or nonsteady aerodynamics (buffeti ng) a rapidly varying component is introduced into the probe telemetry Doppler data. These effects can be isolated by their respective Doppl er signatures. Analysis of residuals allows fine structure in the wind profile to be located and retrieved. The overall wind recovery is a t hree-step process: (1) The large-scale zonal wind profile is recovered by converting the probe telemetry frequency residuals (as caused by t he Doppler effect) to a velocity and back-projecting it into the local horizontal east-west direction at the probe location. The zonal winds are derived from the velocity residuals by a least squares algorithm. (2) Regions of high zonal wind shear are recovered numerically relati ve to the large-scale wind structure and serve as a correction to the previously derived large-scale profile. (3) The probe trajectory is up dated to reflect both the large- and small-scale wind structure, and t he large-scale wind profile is recalculated. The Galileo Doppler wind experiment described previously and the wind microstructure retrieval algorithm outlined here are the only reasonable means by which the ver tical profile of the zonal winds at Jupiter can be directly sampled.