1 / 15

Norbert Krupp, Elias Roussos MPS, Katlenburg -Lindau, Germany Aikaterini Radioti, Denis Grodent

Open-Close Field line Boundary Characterization of Saturn‘s magnetosphere using Cassini MIMI-LEMMS data and auroral observations from HST and Cassini-UVIS. Norbert Krupp, Elias Roussos MPS, Katlenburg -Lindau, Germany Aikaterini Radioti, Denis Grodent LPAP, Liege, Belgium

chyna
Download Presentation

Norbert Krupp, Elias Roussos MPS, Katlenburg -Lindau, Germany Aikaterini Radioti, Denis Grodent

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Open-Close Field lineBoundaryCharacterizationofSaturn‘smagnetosphereusing Cassini MIMI-LEMMS dataandauroralobservationsfrom HST and Cassini-UVIS Norbert Krupp, Elias Roussos MPS, Katlenburg-Lindau, Germany Aikaterini Radioti, Denis Grodent LPAP, Liege, Belgium Donald G. Mitchell JHUAPL, Laurel, MD, USA Michele K. Dougherty Imperial College, London, UK

  2. Previouswork: Mitchell et al, 2009 • electron beam width < 3 deg • accelerationregion < 1 RS • electronbeamsassociatedwithionconics

  3. Previouswork: Belenkayaet al, 2011 HST UV images of Saturn’s southern auroras, projected onto a spheroidal surface 1100 km above the atmospheric 1 bar level, The locations of the poleward and equatorward boundaries of the emission in each image are shown by red crosses, The superposed solid orange lines show the open field regions Mappings of field lines itoquatorialplane (blue and purple squares for the equatorward and polewardboundaries) the two inner circles centred on the planet (black dot) show the inner and outer boundaries of the equatorial ring current, the red line corresponds to the boundary between open and closed field lines.

  4. Previouswork: Gurnett et al. GRL 2010 Indicationsfor open-closedfieldlineboundary: • low-energyelectrondensitydrop • auroral hiss • ratioofdiff.intensitiesfromfield-alignedenergeticelectronswiththe same energy but oppositiedirectionsis a proxyof open-closedfieldlineconfiguration: ratio = 1 (CLOSED) ratio ≠ 1 (OPEN)

  5. Cassini MIMI/LEMMS orientationandpitch angle coverage HE LE

  6. Cassini MIMI/LEMMS orientationandpitch angle coverage HE LE

  7. Example165 deg SR = 5 RSL = 30-40 closed open ??? MIMI/LEMMS pointingalongfielddirectionduringwholeperiod S/C staring large asymmetry in intensitiesmeasured in low-energy end comparedto high-energy end pitchangle 180 degrees in thesouth possiblecrossingof open-closedfieldlineboundary intensityincreaseby 3 ordersofmagnitude !!  electronsmovealongthe open fieldlineawayfromtheplanet‘ssouth pole towardsthe S/C

  8. Example240degNR = 18 RSL = 40 MIMI/LEMMS pointingalongfielddirectiononlyshortlyduring S/C rotation S/C rotating large asymmetry in high energy end pitch angle 0 degrees in thenorth beamsonlyeverysecond S/C rotation(?) electronsmovealongthe open fieldlineawayfromthenorth pole towardsthe S/C highlycollimatedbeams

  9. Example353 degNR = 23 RSL = 65 MIMI/LEMMS pointingalongfielddirectiononlyshortlyduring S/C rotation lS/C rotating large asymmetry in low-energy endfirstthenin high energy end pitch angle 0 degrees in thenorth  electronsmovealongthe open fieldlineawayfromtheplanet‘snorth pole

  10. Time periodsofasymmetries in field-alignedelectronintensities in Saturn‘smagnetosphere Cassini MIMI/LEMMS dataJuly 2004-July 2011 50 time periodsinterpretedasperiodswhen Cassini was on open fieldlines

  11. Locations of open fieldlines in Saturn‘smagnetosphereusingoffsetdipole (green) or Khurana fieldmodel (red) noon-midnightcut dawn-duskcut

  12. Traces ofthe open fieldlinelocationsin theauroralzone Southern hemisphere questionable Northern hemisphere

  13. The location of the main ring of emission varies, but mainly the tracingispoleward of the emission, thus on open fieldlines 2008_195 NORTH 2008_195 NORTH RED: Currentsheet model GREEN: dipole BLUE: Khurana 18 LT Emissions that are associatedwith open fieldlines (bifurcations: signatures of reconnectionat the magnetopause, Radioti et al, submitted ) 12 LT 08/07/2011 2008_129 NORTH 2008_334 NORTH 2008_197 SOUTH

  14. Comparison with recent Cassini/CAPS results: mapping of the cold and hot beam-like populations down to the ionosphere using a dipole within 20 RS Northern Southern see Poster by Arridge et al.

  15. Conclusionsandnextsteps • 50 eventsofhighlycollimatedfield-alignedelectronsarefoundin Cassini MIMI/LEMMS data • interpretedasopen lineregionsin Saturn‘s high latitudemagnetosphere • Observationsof open fieldlineswhen Cassini was at 35-75 S and 20-72 N degreeslatitudes • open fieldlinesmapnicelypolewardofthemainauroral oval whencomparedwithCassini/UVIS images • To do list: • includeclosedfieldlinetracingwhenlookingalongthefieldfor a betterdeterminationof open-closedboundary • Determinewidthofelectronbeams • Comparisonwithotherdatasets

More Related