Pioneer 10 and 11 Observations and the Dynamics of Jupiter's Atmosphere

Abstract

Three new results of the Pioneer 10 and 11 mission are discussed. The first is that effective temperature is the same at the poles and equator in spite of the large differences in solar energy deposition. This is consistent with theories of convection which suggest that an extremely small equator-to-pole temperature difference at the level of infrared emission could suppress the internal heat flux at the equator relative to the pole by an amount sufficient to balance the difference in solar energy deposition. The second result is that the effective temperature of belts is 3 to 4K greater than that of zones, which is almost exactly accounted for by the lower albedo of belts. This result cannot be interpreted uniquely, but is consistent with a model in which the internal heat flux is the same under belts and zones, and the horizontal atmospheric heat flux is zero. The third observation provides evidence of instability along the south edges of zones in the northern hemisphere. These are the latitudes of minimum prograde velocity, where instability is most likely to occur in a barotropic fluid, as pointed out by Ingersoll and Cuzzi (1969). A more realistic baroclinic stability analysis suggests instability at these same latitudes.