Infrared Observations of Jupiter’s Ionosphere
thesisposted on 05.06.2018, 15:20 by Rosie Eleanor Johnson
In this thesis I have used infrared observations of Jupiter to investigate the flows of ions in the ionosphere and how they are coupled to the ionospheric heating in the auroral regions, determining the drivers of the heating and how they are related to the thermosphere and the magnetosphere. I investigated the H3+ line-of-sight velocity in the mid-to-low latitude region, derived from the Doppler shift of the Q(1,0-) emission line taken by IRTF-CSHELL. No evidence of flows in the region of the H Ly-α bulge predicted by a global circulation model were measured, and the H3+ ions in the mid-to-low latitude region were found to be corotating. Using observations taken by VLT-CRIRES, polar projections of the intensity and line-of-sight velocity of the H3+ ions in Jupiter’s northern auroral region were created. This revealed the ionospheric flows and how they relate to different morphological regions of the northern aurora. These flows vary from extremely sub-rotational to super-rotational, and the drivers of the flows range from the solar wind and magnetospheric interaction to a potential thermospheric driver. The same set of VLT-CRIRES observations are then used to derive the rotational temperature, column density, and total emission of the H3+ ions in the northern auroral regions. These properties were mapped onto polar projections, which revealed changes in temperature during the observations (over a short period of ~80 minutes). The changes in temperature could be caused by local time changes in particle precipitation energy, or they could be caused by the thermospheric response to a transient enhancement of solar wind dynamic pressure, as predicted by models. By comparing all of the H3+ properties, the complex interplay between heating by impact from particle precipitation and Joule heating, as well as cooling by the H3+ thermostat effect was revealed.