M3-I2 Session 2 - Ionosphere Boundary to Outflow
Notes by Barbara Giles and the M3-I2 session leaders. Shasha Zou moderated the session.
Shasha Zou directs the session and discussion on the modeling and measurement of ionosphere upflow to outflow process. In her introduction she identifies the Bob Strangeway et al, 2005 flow chart as a useful starting place for a discussion on the outflow processes from the ionosphere. The question on what drives upflow to outflow and is it multiple processes for different regions of the polar ionosphere: Joule dissipation (ion scale height), electron heating (scale height), kinetic flow processes (non-Maxwellian flow), and/or wave-particle heating. Defining the ionospheric boundary may be very important for outflow modeling and GPS TEC can provide important structure definition of the polar conditions during storms. The main questions for this session on the ionospheric boundary definition for the upflow and outflow of ionospheric plasma are:
Roger Varney (SRI) (invited speaker) presents on “Areas for Improvement in Ion Outflow Modeling.” He identifies a number of effects that need to be defined within the models to obtain realistic ion outflow for M-I coupling. Neutral winds (vertical winds) within the Cusp regions can lift the ionosphere dramatically to initiate ion upflow. The elevated neutral densities from soft precipitation in the cusp can cause a vertical lift of ~150 m/s. These are non-hydrostatic flows, but the models stop at 600km. There is a need for kinetic exosphere models.
Ion energization through wave-particle interactions is poorly defined but very important. The temperature anisotropy (Tperp/Tpar = 5) is a source of free energy for instabilities. Candidates for wave-particle interactions are numerous: Landau resonance with BBELF waves, Landau resonance with EMIC waves, others. Altitude of energization (W-P) is the big question [Bouhram et al. 2004; Barghouthi et al. 1997, 1998; Retterer et al. 1987]. SCIFER sees energization at 1200 km and higher, SERSIO sees it at 520-780 km in cusp, AMICIST sees ELF heating at 880km.
In the cusp and auroral region it might be important to handle the parallel E fields in a self-consistent treatment of high latitude electric fields. These may be important for collisionless plasmas. Generally the Knight relation for e acceleration for regions of upward current is used within models.
Comments to Roger Varney’s talk:
George Khazanov (NASA/GSFC) presents a invited talk entitled “Kinetic modeling is a Must”. The M-I system is a complicated system with important differences in the altitude ranges: Collisional (100 to 1000km), semi-collisional (1000 to 2500km), and collisionless (2500 up). Fokker-Planck code is important for ion outflow (Khazanov and Liemohn, 1997-2000). Kinetic model of H+ and O+ is necessary with at least Maxwellian e with super thermal electrons added.
Shunrong Zhang (Millstone Hill Radar) gives an overview of ISR capability. The ISRs can see plasma upflow at ~400km during disturbed conditions. Madrigal CEDAR website is open to explore these data.
Bruce Fritz (U. of New Hampshire) reviews the potential science of the RENU2 rocket flight. It measures neutral upwelling in cusp region, N2+ emissions for plasma flow, indicates that Alfven waves drive electron precipitation.
Doug Roland reviews the potential science of VISION rockets
W.K. (Bill) Peterson (LaSP) reviews the status of the ePOP experiment. The satellite has been spin stabilized. It carries a radio receiver, GPS instruments, ion mass spectrometer, scintillation monitor, and a magnetometer. The mass spectrometer measures thermal ion energy range from 1 to 10 V. It sees N+ and O+ and Low flux of NO+ and O2+. Currently only quantitative estimates of outflow distributions can be generated. The data is limited to 5-minute passes a day over US (composition, velocity, energy). Input is requested to define measurement period to optimize science.
