Measuring the seeds of ion outflow: auroral sounding rocket observations of low-altitude ion heating and circulation
Journal Article
·
· Journal of Geophysical Research. Space Physics
- Dartmouth College, Hanover, NH (United States); Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
- Dartmouth College, Hanover, NH (United States)
- Embry-Riddle Aeronautical Univ., Daytona Beach, FL (United States)
- Univ. of Alaska, Fairbanks, AK (United States)
- Univ. of Oslo (Norway)
- Univ. of New Hampshire, Durham, NH (United States); Johns Hopkins Univ., Laurel, MD (United States)
- Univ. of New Hampshire, Durham, NH (United States)
- Johns Hopkins Univ., Laurel, MD (United States); Cornell Univ., Ithaca, NY (United States)
- Univ. of Maryland, College Park, MD (United States); NASA Goddard Space Flight Center (GSFC), Greenbelt, MD (United States)
- Cornell Univ., Ithaca, NY (United States)
Here, we present an analysis of in situ measurements from the MICA (Magnetosphere-Ionosphere Coupling in the Alfvén Resonator) nightside auroral sounding rocket with comparisons to a multifluid ionospheric model. MICA made observations at altitudes below 325 km of the thermal ion kinetic particle distributions that are the origins of ion outflow. Late flight, in the vicinity of an auroral arc, we observe frictional processes controlling the ion temperature. Upflow of these cold ions is attributed to either the ambipolar field resulting from the heated electrons or possibly to ion-neutral collisions. We measure E→xB→ convection away from the arc (poleward) and downflows of hundreds of m s-1 poleward of this arc, indicating small-scale low-altitude plasma circulation. In the early flight we observe DC electromagnetic Poynting flux and associated ELF wave activity influencing the thermal ion temperature in regions of Alfvénic aurora. We observe enhanced, anisotropic ion temperatures which we conjecture are caused by transverse heating by wave-particle interactions (WPI) even at these low altitudes. Throughout this region we observe several hundred m s-1 upflow of the bulk thermal ions colocated with WPI; however, the mirror force is negligible at these low energies; thus, the upflow is attributed to ambipolar fields (or possibly neutral upwelling drivers). Moreover, the low-altitude MICA observations serve to inform future ionospheric modeling and simulations of (a) the need to consider the effects of heating by WPI at altitudes lower than previously considered viable and (b) the occurrence of structured and localized upflows/downflows below where higher-altitude heating rocesses are expected.
- Research Organization:
- Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
- Sponsoring Organization:
- USDOE
- Grant/Contract Number:
- AC52-06NA25396
- OSTI ID:
- 1240689
- Report Number(s):
- LA-UR--15-29126
- Journal Information:
- Journal of Geophysical Research. Space Physics, Journal Name: Journal of Geophysical Research. Space Physics; ISSN 2169-9380
- Publisher:
- American Geophysical UnionCopyright Statement
- Country of Publication:
- United States
- Language:
- English
Transient Ionospheric Upflow Driven by Poleward Moving Auroral forms Observed During the Rocket Experiment for Neutral Upwelling 2 (RENU2) Campaign
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journal | June 2019 |
A New Framework to Incorporate High‐Latitude Input for Mesoscale Electrodynamics
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journal | January 2020 |
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