[GEM] THE GEM MESSENGER, Volume 26, Number 43

Newsletter Editor editor at igpp.ucla.edu
Mon Oct 24 23:13:11 PDT 2016


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     THE GEM MESSENGER
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Volume 26, Number 43
Oct.25,2016

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Table of Contents

1. 2016 GEM-CEDAR Workshop Report: Merged Modeling & Measurement of Injection Ionospheric Plasma into the Magnetosphere and Its Effects (M3-I2) Focus Group

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1. 2016 GEM-CEDAR Workshop Report: Merged Modeling & Measurement of Injection Ionospheric Plasma into the Magnetosphere and Its Effects (M3-I2) Focus Group
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From: Vince Eccles, Shasha Zou, and Barbara Giles (vince.eccles at aggiemail.usu.edu)

M3-I2 held four sessions during the GEM/CEDAR Joint Workshop. The first focused on the magnetospheric effects of ionospheric injection. The second focused on the ion upflow and outflow physics from the ionospheric boundary through the topside ionosphere to the polar wind. The third and fourth sessions focused on collaboratively integrating these two areas in physics discussions and planning. 

Session 1: Monday PM1 - Status, Questions, & Opportunities: Magnetospheric Effects of Ionospheric Injection

It has become apparent to the magnetospheric and inner magnetospheric modeling community that model results are dramatically altered by the presence and placement of ionospheric ions throughout the magnetosphere. Both quiet time and storm time ionospheric upflow and outflow must be correctly established to advance a better understanding of the magnetosphere-ionosphere-thermosphere (M-I-T) coupled system. This must be a GEM-CEDAR joint effort to address: 

• the ionosphere boundary layer,
• the ion energization region of the polar wind
• the magnetospheric response to solar wind drivers and the ionospheric outflow
• the feedback into the lower ionosphere-thermosphere 

Invited speakers reviewed the status of current understanding and modeling of the effects of ionospheric ion injections on the magnetosphere. The GEM Focus Group Chairs presented goals-overview of plans and moderate a discussion on new in situ observational opportunities for metric studies on plasma sheet, ring current, and substorm dynamics to direct improvements in the current Geospace General Circulation Models (GGCMs). 

Charles R. Chappell (invited speaker) of Vanderbilt University reminds the GEM community of the necessary but slow paradigm shift towards viewing the ionosphere as the dominant source of magnetospheric plasma. In the 1960s the solar wind plasma was viewed as the dominant source. The earth's polar wind of ionospheric outflow was identified in the 1970s and there was a substantial increase in observations of O+, H+, and He+ outflow in the 1980s. The main magnetosphere models and theoretical studies did not account for these observations until the late 1990s. In the 2000s the new paradigm begins to take hold with the move towards multiple species MHD models and coupling with polar wind outflow models. A recent Chapman Conference has produced a book on the effects of ionospheric outflow on the whole magnetosphere system (due out soon). Continued studies on the effects on the different magnetosphere regions are needed to complete the community's full shift to the new perspective of the ionosphere-magnetosphere system. Because the magnetosphere community primarily uses MHD models it is necessary to include Delcourt ion trajectory studies [Delcourt et al., 1993] to follow the history of injected ions. This helps explore the process of populating the different regions and the energization of these ion populations.

Dan Welling (invited speaker) of the University of Michigan stated the primary result from the coupling of ionospheric outflow models and MHD magnetosphere models: Outflow Really Matters! A number of effects observed: (1) dayside reconnection rate influenced by cold plasma presence, (2) polar cap potential is reduced (or limited) with increased presence of O+, (3) the magnetosphere tail is stretched, (4) fast outflows escape through the tail but slow populations 'hang around' to increase their relative importance and influence, (5) source location and composition of the outflow matters to different magnetosphere regions, (6) O+ cusp outflow can influence the initiation of a substorm, which causes nightside auroral ion outflow, which can drive subsequent sawtooth substorms, (7) ring current calculations are improved with better H+/O+ composition in the ring current region. The final conclusion is that the coupled ionosphere-magnetosphere behavior needs to be studied in greater detail because the magnetosphere affects the ionosphere, affects the magnetosphere, affects the ionosphere, affects ... A final suggestion was put forward that magnetosphere models need a minimum of three ion fluids: H+ from the solar wind, H+ from the ionosphere, and O+ from the ionosphere. 

Subsequent speakers provided a short synopsis of their current work. 

Barbara Giles of Goddard Space Flight Center/NASA presented a survey of the Magnetospheric Multiscale (MMS) Mission, which are available at https://lasp.colorado.edu/mms/sdc/public/ website. One quick observation from the FPI shows that H+, He+, O+ species are seen in the Warm Plasma Cloak. 

Naritoshi Kitamura of ISAS/JAXA presented MMS FPI data showing O+ 1000 eV beam and H+ 100 eV beams in the tail lobe in nightside region. Dayside shows no O+ beams but H+ beams are structured between 100 to 1000 eV. 

Matina Gkioulidou of APL Johns Hopkins University presented Van Allen Probe ring current observations. O+ outflow at 300 eV is seen during storm periods with multiple bands of energy in the O+ outflow. Additional O+ outflow observed in the post midnight sector begs the question on the source region: is it Joule heating or auroral processes? 

Jonathan Krall of NRL presented SAMI3 model results of the plasmapause. The dawn side plasmapause is most evident in the model results. Rick Chappell commented that the drift of plasma from noon to nightside generally produces this steepening on the dawn side. The SAMI3 results may be capturing this effect. 

Chris Mouikis of University of New Hampshire presented a Dst epoch study of outflow for isolated moderate storms. The storm epochs were divided into pre-storm, main phase, early recovery and late recovery. Magnetic local time & latitude dial plots of H+ outflow and O+ outflow demonstrated clear trends through the storm epochs. This is an excellent study to be used as a benchmark for ionospheric outflow model results. 

Lynn Kistler of University of New Hampshire has gathered multi-satellite, multi-instrument measurements of a particular storm with sawtooth oscillations. LANL was used for sawtooth identification, ACE for solar wind drivers, CLUSTER for plasma sheet O+ presence, FAST for auroral outflow, IMAGE for auroral morphology. She is producing a morphology of the magnetosphere-ionosphere (M-I) interactions during sawtooth substorm events of October 1, 2001. Dr. Kistler presented an early conclusion that the 1st observed sawtooth substorm may be connected to auroral outflow from the previous substorm (10 eV O+ outflow observed in nightside). The next sawtooth substorm seemed to be connected to cusp outflow.  

Session 2: Monday PM2 - Status, Questions, & Opportunities: Polar Wind and the Ionospheric Boundary

This session was to review the status of current understanding and modeling of ion outflow to the magnetosphere initiated in the ionospheric boundary. There are many open questions on ion energization for the ionospheric polar wind that the community still must address. However, to address this question properly, the spatial and temporal variations of the ionospheric boundary (below 600km) must be defined accurately in the polar and sub-auroral regions for appropriate comparison of PW model results to satellite data. This effort should strive to marshal new in situ and ground-based observational abilities with current modeling capabilities to addressing these open issues. 

Convener Shasha Zou identifies the flow chart of Strangeway et al. [2005] as a useful starting place for a discussion on the outflow processes from the ionosphere. There are multiple processes for different regions of the polar ionosphere that drive ion outflow such as Joule dissipation (ion scale height), electron heating (scale height), kinetic flow processes (non-Maxwellian flow), and wave-particle heating. Defining the ionospheric boundary will be very important for outflow modeling. GPS TEC can provide important structure definition to the ionosphere plasma content. Incoherent scatter radars can help define F region and topside conditions in sub auroral and polar regions. The main questions for the upflow and outflow of ionospheric plasma are:

What are the energization processes?
How influential is the spatial and temporal structuring of the ionosphere?
What are the differences over the ranging seasonal and solar conditions? 

Roger Varney (invited speaker) of SRI identified areas for improvement in ion outflow modeling. First, the vertical neutral winds within an active cusp region can lift the ionosphere dramatically to initiate ion upflow. Soft precipitation and Joule heating in the cusp can help cause a vertical lift of up to 150 m/s. These represent non-hydrostatic flows in the thermosphere. One of the issues in thermospheric modeling is that the models stop at 600 km. There is a need to extend into the kinetic exosphere altitudes. Second, ion energization through wave-particle interactions is poorly defined, but it is very important. The ion temperature anisotropy (Tpara/Tperp ~ 5) is a source of free energy for instabilities. Candidates for wave-particle interactions are numerous: Landau resonance with broadband extremely low frequency (BBELF) waves, Landau resonance with electromagnetic ion cyclotron (EMIC) waves, and others. The altitude range of the energization by wave-particle processes is the big question [Bouhram et al. 2004; Barghouthi et al. 1997, 1998; Retterer et al. 1987]. Structure of the Cleft Ion Fountain sounding rocket (SCIFER) sees energization at 1200 km and higher. The Svalbard EISCAT rocket study of ion outflows (SERSIO) sees it at 520-780 km in cusp. The AMICIST sounding rocket sees ELF heating at 880km. Storms, solar cycle, season and polar region may influence energization altitudes. Third, 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. The parallel fields may be important within collisionless plasmas. Subsequent discussion on Roger Varney’s presentation identified the need for kinetic plasma models to address wave-particle interactions fundamentally. Current modeling that assigns an altitude range is insufficient since the size of heating region may be limited in altitude, horizontal region, and in time. Transport models need dynamic parameterization or fundamental model to provide best results. 

George Khazanov (invited speaker) from Goddard Space Flight Center/NASA divides the M-I system into the altitude ranges of: collisional (100 to 1000km), semi-collisional (1000 to 2500km), and collisionless (2500 up). Fokker-Planck physics is important for ion outflow (Khazanov and Liemohn, 1997-2000) with kinetic modeling for H+ and O+ with at least Maxwellian electron fluid with super thermal electrons added. 

Subsequent speakers provided a short synopsis of their current work. 

Shunrong Zhang from Millstone Hill Radar provided an overview of ISR capability for observing plasma upflow at ~400km during disturbed conditions. Madrigal CEDAR website is available to explore these data. 

Bruce Fritz of the University 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 can drive electron precipitation. 

Doug Roland reviewed the potential science of VISION rockets. 

W.K. (Bill) Peterson of Laboratory for Atmosphere and Space Physic reviewed the ePOP experiment. 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 and it sees N+ and O+ fluxes and low flux values 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.

Session 3 & 4: Friday PM - Recap, Organize, And Planning

These sessions were provided to reviewed the earlier sessions and plan for future focus area studies. 

Robert Strangeway (invited speaker) of UCLA presented the importance of understanding the ion outflow physics in the terrestrial environment as well as other planets. He briefly reviewed the terrestrial observations, which highlight that precipitating electron density is the single best controlling factor for ion outflow but also the hardest to parameterize in models. He then talked about several areas for progress necessary to further advance our understanding of ion outflow physics. For example both dayside and nightside data show there is a lower flux limit and upper flux limit to ion outflow. Multi-species coupled ionosphere-thermosphere-magnetosphere models are a necessary step. However, the anisotropy of the ion distributions in the magnetosphere must be addressed in the MHD transport models.

Naritoshi Kitamura (invited speaker) of Institute of Space and Astronautical Science (ISAS/JAXA) presented a comparison between the USU Generalized Polar Wind model results and the Akabono satellite data. He found that the model prediction of ion density was 30-500 smaller than observations in these middle altitudes (~2000 km) within the polar cap. There is much work to be done in the model-measurement comparisons for the different regions of the aurora, cusp, and polar cap. Dr. Kitamura gave the important caution that the H neutral profile of MSIS is wrong. The important resonant reactive collision between H and O+ and O and H+ will be strongly affected by the incorrect H profile within MSIS.  

Open flow discussions on the science and plans of the M3-I2 focus group hit on previously identified points from the earlier sessions.

First, ion outflow particle energy and location of the outflow from the ionosphere are important because they determine where the ion populations go in the magnetosphere. Delcourt Ion tracing studies are important for this effort to examine ion energization history within the magnetosphere and to determine ion distributions in the different regions. These are necessary insights into the examination of MHD model magnetic fields configurations when comparing ion measurements with the models. The kinetic populations derived from the ray tracing can also identify where MHD models can benefit from kinetic physics parameterizations. 

Second, magnetospheric models need to incorporate kinetic physics due to the anisotropic particle distributions. Parameterizations of heat flux along magnetic field lines in MHD models can be the next advance in MHD modeling of the magnetosphere. It is also important to understand why MHD so successful in modeling the magnetosphere. Is this a tuning of fudge factors or an accidental strength of MHD in the plasma regimes of the magnetosphere?  Third, because ion outflow affects ring currents, substorms, plasma sheet, and reconnection, it will be important to collaborate with the different GEM focus groups in these areas. 

Third, the energization processes within the ion upflow/outflow models is currently poorly understood and modeled. The ionospheric boundary must be defined properly within these models to make proper one-to-one comparisons of models and measurements. Potentially, data assimilation can be used to define the polar, auroral, subauroral regions of the ionospheric boundary. This can be used to benchmark coupled M-I models and to drive the lower boundaries of ion upflow models. There needs to be a fundamental plasma physics modeling study to better understand the wave-particle energization processes thought to be important in the ion outflow.

Finally, the workshop turned towards defining specific storm periods useful for model-measurement comparisons. There should be continuing studies using older data sets from Cluster, Polar, LANL, Akebono, Themis, and Geotail. These observations should be compared with new satellite data sets for similar conditions to insure interpretive continuity. It was also noted that experimentalists use different units than modelers when discussing energy flow, sources, and sinks. The best units for experimentalists are eV/cm2/s for flow and eV/cm3 /s for deposition or sources. 

Several dates were put forward for the different altitude regions for addressing M3-I2 issues: 

• TOPSIDE ALTITUDES (500-2000km): Ion upflow/outflow models should first compare against solar angle climatologies for benchmark topside ionosphere modeling. Some data periods for topside altitudes are supported by several satellites (DMSP, FAST) and ISRs.
• 2000 Oct 24, 1998 Jan 27, and 2002 Jan 20 (ISR-FAST conjunction).
• MIDDLE ALTITUDES (2000-5000km): Polar Satellite is a good source of data for these altitudes. 1997 Jan 10-11 has good comparisons with Geotail, Wind, FAST, Freia. 2000 Apr 6-7 has Akebono, FAST, POLAR support.
• MAGNETOSPHERE (beyond 2 Re): 2015 Dec 31, 2016 Jan 20, 2016 Mar 6-8, 2015 Jun 22-23. All have multi-satellite support. 


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