Infrared polar brightenings on Jupiter. V. A thermal equilibrium model for the north polar hot spot

Infrared hydrocarbon emissions from Jupiter's north polar region, recorded using the Voyager IRIS instrument, determine spatial and other properties of the north polar hot spot. Emission at 7.8 μm by stratospheric methane reveals that the peak is asymmetric with respect to system III longitude. A thermal equilibrium model exploits this asymmetry to derive an estimate for the zonal wind velocity in the stratosphere. The same model predicts accurately the observed asymmetry in acetylene emission at 13.6 μm, but requires that the acetylene abundance be enhanced in the hot spot. Ethane, in contrast, appears to be depleted. Energetic charged particles are the most probable cause of these effects; their energies determine the altitude of the hot spot in the stratosphere, estimated here to be between the 1-mbar and 1-μbar pressure levels.