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Title: Measuring the seeds of ion outflow: auroral sounding rocket observations of low-altitude ion heating and circulation

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 ExB 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 (ormore » 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.« less
 [1] ;  [2] ;  [3] ;  [4] ;  [5] ;  [6] ;  [4] ;  [2] ;  [2] ;  [7] ;  [8] ;  [9] ;  [5] ;  [10]
  1. Dartmouth College, Hanover, NH (United States); Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  2. Dartmouth College, Hanover, NH (United States)
  3. Embry-Riddle Aeronautical Univ., Daytona Beach, FL (United States)
  4. Univ. of Alaska, Fairbanks, AK (United States)
  5. Univ. of Oslo (Norway)
  6. Univ. of New Hampshire, Durham, NH (United States); Johns Hopkins Univ., Laurel, MD (United States)
  7. Univ. of New Hampshire, Durham, NH (United States)
  8. Johns Hopkins Univ., Laurel, MD (United States); Cornell Univ., Ithaca, NY (United States)
  9. Univ. of Maryland, College Park, MD (United States); NASA Goddard Space Flight Center (GSFC), Greenbelt, MD (United States)
  10. Cornell Univ., Ithaca, NY (United States)
Publication Date:
OSTI Identifier:
Report Number(s):
Journal ID: ISSN 2169-9380
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Journal of Geophysical Research. Space Physics
Additional Journal Information:
Journal Name: Journal of Geophysical Research. Space Physics; Journal ID: ISSN 2169-9380
American Geophysical Union
Research Org:
Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
Sponsoring Org:
Country of Publication:
United States
47 OTHER INSTRUMENTATION; 70 PLASMA PHYSICS AND FUSION TECHNOLOGY auroral ionosphere; sounding rocket; low-altitude heating; fine-scale structure; ion upflow and downflow; electrostatic analyzer