Processes of equatorial thermal structure at Jupiter: An analysis of the Galileo temperature profile with a three-dimensional model

摘要

The Jupiter Thermospheric General Circulation Model (JTGCM) calculates the global dynamical structure of Jupiter's thermosphere self-consistently with its global thermal structure and composition. The main heat source that drives the thermospheric flow is high-latitude Joule heating. A secondary source of heating is the auroral process of particle precipitation. Global simulations of Jovian thermospheric dynamics indicate strong neutral outflows from the auroral ovals with velocities up to ～1.2 km/s and subsequent convergence and downwelling at the Jovian equator. Such circulation is shown to be an important process for transporting significant amounts of auroral energy to equatorial latitudes and for regulating the global heat budget in a manner consistent with the high thermospheric temperatures observed by the Galileo probe. Adiabatic compression of the neutral atmosphere resulting from downward motion is an important source of equatorial heating from the top boundary of the JTGCM to 0.06 μbar. The adiabatic heating continues to dominate between 0.06 and 0.2 μbar, but with the addition of comparable heating due to horizontal advection induced by the meridional flow. Thermal conduction plays an important role in transporting heat down to lower altitudes (>0.2 μbar). The total heating transported in this region is radiated away by infrared hydrocarbon cooling via CH4 (7.8 μm) and C2H2 (12.6 μm) emissions.