P41B-2070
Global Response of the Upper Thermosphere to Large Ion Drifts in the Jovian Ovals
Thursday, 17 December 2015
Poster Hall (Moscone South)
Tariq Majeed1,2, Stephen W Bougher2, Aaron J Ridley3, Randy Gladstone4, Jack H Waite Jr5 and Jared Micheal Bell6, (1)American University of Sharjah, Physics, Sharjah, United Arab Emirates, (2)University of Michigan Ann Arbor, Ann Arbor, MI, United States, (3)University of Michigan Ann Arbor, AOSS, Ann Arbor, MI, United States, (4)Southwest Research Inst, San Antonio, TX, United States, (5)Southwest Research Institute San Antonio, San Antonio, TX, United States, (6)National Institute of Aerospace, Yorktown, VA, United States
Abstract:
We use our fully coupled 3-D Jupiter Thermosphere General Circulation Model (JTGCM) to quantify wind processes that are responsible for generating neutral winds in the auroral thermosphere from 20 μbar to 10-4 nbar self-consistently with the thermal structure and compositions. The heat sources in the JTGCM that drive the global circulation of neutral flow are charge particle heating from particle impact of extreme auroral conditions and large amount of Joule heating produced in the Jovian ovals by imposing high speed anticorotational ion drifts up to ~3.5 kms-1. These sources are strongly related to the current system in the equatorial plasma sheet that allows plasma to flow outward from the ionosphere to the magnetosphere in the inner part and return from the magnetosphere to the ionosphere in the outer part. We find that strong pressure gradients are developed in the auroral regions, affecting zonal and meridional winds in addition to local temperature distributions. We also find that the zonal flow of neutral winds in the ovals of both hemispheres is primarily driven by competition between Coriolis forcing and ion drag processes near the ionospheric peak. However, above the ionospheric peak, the acceleration of neutral flow due to pressure gradients is found to be the most effective parameter impacting zonal winds. One of the most important findings of this investigation is that the meridional flow of neutral winds in the Jovian ovals is poleward near the peak of the auroral ionosphere. The strength of this flow is gradually weakened and turned equatorward at the sub-nanobar levels with wind speeds up to ~250 ms-1 in the southern oval and ~75 ms-1 in the northern oval. The corresponding neutral motion in this region is upward with wind speeds up to 4 ms-1 in both ovals. We will discuss the model assumptions, numerical framework and several parameterizations of inputs quantities. Comparisons of key model outputs (e.g. neutral temperatures and wind components) will be provided.
