Evidence of Heat Transport from Jupiter's Polar Ionosphere to Lower Latitudes Found in Ground-based Keck-telescope Maps of Jupiter's Ionospheric H3+

Abstract:

The non-auroral ionospheres of Jupiter, Saturn and Uranus have been regularly observed to be hundreds of Kelvin hotter than models can explain based on solar heating alone. Finding the missing heat source and mechanism has been a problem in the field of ionospheres for several decades, and it is generally termed in literature as the "giant planet energy crisis". One way to apparently cause heating in the non-auroral ionosphere is to redistribute heat from the auroral ionosphere at the poles down to lower latitudes: the auroral region itself is heated thermally by collisions as a result of the auroral mechanism. However, the majority of models of global circulation predict that heat within the polar/auroral is confined there by Coriolis forces, such that auroral energy cannot be communicated to lower latitudes. Until now, there have been no high-spatial-resolution observations of temperature in the auroral region simultaneous with non-auroral regions to confirm whether or not this actually happens. In this presention we will present ground-based observations of Jupiter's ionospheric H3+ temperature at high spatial resolution (~1000km per pixel). H3+ is a major ion at Jupiter, considered in quasi-thermodynamic equilibrium with its surroundings, and therefore a good proxy for energy balance of the ionosphere. These observations, taken by the 10-meter Keck telescope on April 14, 2016 and Jan 25, 2017, strongly suggest heat from the auroral region is spreading to lower latitudes, such that the missing heat source causing the "energy crisis" may ultimately be auroral in nature.