Voyager Infrared Observations of the Outer Solar System
Abstract
During the Voyager 1 and Voyager 2 encounters with Jupiter and Neptune, global mapping sequences (known as the north-south maps) were obtained by the Infrared Interferometer Spectrometer (IRIS). Previously performed inversions of these spectra allow the maps to be converted to digital images of various atmospheric properties. Fourier transforms of these images indicate significant longitudinally periodic structure. Cross-correlations of the Jupiter maps show that the thermal fields are dominated by large slow or stationary features, despite substantial aerosol velocities at those pressure levels. Two mechanisms are proposed as explanations for the above. The first, forcing from the non-rotating deep atmosphere, is explored analytically. It is found that a pressure perturbation can vertically extend its influence parallel to the planetary rotation axis without attenuation within the adiabatic interior. For the second explanation, horizontal influence, a numerical model is developed in which resonances within an equatorial channel are initiated by a meridional perturbation velocity at one boundary. Resonances are found as functions of thickness of a "weather layer", density discontinuity between that layer and the deep atmosphere, and the change in the background zonal velocity with depth. The first model applies to both Jupiter and Neptune, and predicts features moving at or near the magnetic field rotation rate of the planet. The second can be applied only to Neptune and implies structures moving at the velocity of the supposed forcing feature (e.g. the GDS). The absence of velocity measurements from IRIS data at Neptune means that neither hypothesis can be ruled out.
- Publication:
-
Ph.D. Thesis
- Pub Date:
- 1990
- Bibcode:
- 1990PhDT.........7W
- Keywords:
-
- JUPITER;
- NEPTUNE;
- Physics: Astronomy and Astrophysics, Physics: Atmospheric Science;
- Fronts (Meteorology);
- Infrared Astronomy;
- Infrared Spectra;
- Mathematical Models;
- Solar System;
- Temperature Distribution;
- Thermal Mapping;
- Aerosols;
- Atmospheric Chemistry;
- Cross Correlation;
- Fourier Transformation;
- Infrared Interferometers;
- Infrared Spectrometers;
- Meridional Flow;
- Meteorological Parameters;
- Neptune (Planet);
- Voyager Project;
- Astronomy