Locations of Boundaries
Download
1 / 23

ILWS - 11 Science Workshop, Beijing, China, Aug-Sep 2011 - PowerPoint PPT Presentation


  • 80 Views
  • Uploaded on

Locations of Boundaries of the Outer and Inner Radiation Belts during the Recent Solar Minimum, as Observed by Cluster and Double Star Natalia Ganushkina (1,2) , Iannis Dandouras (3), Yuri Shprits (4) , Jinbin Cao (5,6) Finnish Meteorological Institute, Helsinki, Finland

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about ' ILWS - 11 Science Workshop, Beijing, China, Aug-Sep 2011' - mandar


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.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

  • Locations of Boundaries of the Outer and Inner Radiation Belts during the Recent Solar Minimum, as Observed by Cluster and Double Star

  • Natalia Ganushkina (1,2) , Iannis Dandouras (3), Yuri Shprits (4) , Jinbin Cao (5,6)

    • Finnish Meteorological Institute, Helsinki, Finland

    • University of Michigan, Ann Arbor, USA

    • IRAP (ex-CESR), CNRS / University of Toulouse, Toulouse, France

    • IGPP, University of California, Los Angeles, USA

    • Beijing University of Aeronautics and Astronautics, Beijing, China

    • State Key Laboratory of Space Weather, CSSAR, CAS, Beijing, China

ILWS - 11 Science Workshop, Beijing, China, Aug-Sep 2011


Outline
Outline

  • Introduction: The Terrestrial Radiation Belts

  • Methodology: Analysing the Terrestrial Radiation Belts with low-energy particle instruments : CIS onboard Cluster and HIA onboard Double Star

  • Radiation Belts boundaries locations: Results

  • Conclusion


Omnidirectional integrated electron fluxes (cm-2 s-1 ) trapped in the radiation belt.

From NASA AE8 max model.

Energy > 1 MeV

Omnidirectional integrated proton fluxes (cm-2 s-1 ) trapped in the radiation belt.

From NASA AP8 min model.

Energy > 10 MeV

Omnidirectional differential flux spectra for trapped electrons (AE8 max) and trapped protons (AP8 min)


Cluster and Double Star TC-1 orbits

Cluster:

the “early years” (2000 – 2006)

4 x 19.6 RE

DS TC-1: 2003 - 2007

1.09 x 13.4 RE

Cluster: Orbit evolution since 2007


The CIS Experiment

Onboard Cluster

Onboard Cluster & TC-1

CODIF (CIS-1)

Ion Composition and Distribution Function Analyser

3D ion distributions with mass-per-charge composition determination

~0 - 40 keV/q Energy Range

HIA (CIS-2)

Hot Ion Analyser

3D ion distributions with high angular resolution

5 eV/q - 32 keV/q Energy Range

Rème et al., 2001, 2005


i

Ion 3-D distributions:

E, f, q, t

5 eV/q - 32 keV/q

Cluster & TC-1: CIS / HIA: Hot Ion Analyser


How can we analyse

high-Energy (> MeV) particles

with a low-Energy (< 100 keV) instrument ?


Radiation Belt penetrating particle

i+

Accumulated wall thickness, for HIA onboard Cluster:

Typically 4 mm Al (2 mm minimum)

For HIA onboard Double Star: additional 4 mm Al


Energy of penetrating particles

for HIA and CODIF

CLUSTER: Proton threshold: ~30 MeV Electron threshold: ~2 MeV


Cluster: CIS / CODIF: Ion Composition and Distribution Function Analyser

TOF system

L

i+

Main entrance

i +

e-

Ion 3-D distributionsand mass analysis:

E, m, f, q, t

0 eV/q - 40 keV/q


Boundaries of outer and inner radiation belts as observed by Cluster CIS:Turning instrument background into science data

Background counts (penetrating high-energy particles)

B1

B2

B3

B4

B5

B6

HIA

CODIF

Outer RB

Inner RB

Outer RB

Reduced background due to TOF double coincidence

Ring current ion drift bands


To determine a boundary location:

At a first instance, the spacecraft entry into a radiation belt appears as a substantial, homogeneous increase of count rate over all energy channels.

To more accurately define the boundary position, we then determine the first time momentwhen the Δc/s / Δt are the largest and same for all energy channels(sharpest gradient) and place a boundary there.



Boundaries of outer and inner radiation belts

as observed by Cluster CIS at different orbits

B1

B2

B5

B6

B3

B4

Outer RB

Outer RB

Inner RB

ORB

IRB

ORB


Example of boundaries’ locations at Double Star

B2

B3

B0

B4

B5

Outer RB

Outer RB

Inner

Inner


Locations of Rad-Belt boundaries for all events, MLT distribution (Cluster-CIS data): April 2007 - June 2009

B1 and B6:

outer boundary of

outer RB

B2 and B5:

inner boundary of

outer RB

B3 and B4:

outer boundary of

inner RB

Ganushkina, Dandouras, et al., JGR, in press, 2011


Locations of boundaries for all events with activity indices distribution (Cluster-CIS data): April 2007 - June 2009

B1 and B6:

outer boundary of

outer RB

B2 and B5:

inner boundary of

outer RB

B3 and B4:

outer boundary of

inner RB

Dst: moderate, no change

Kp and AE: decrease


Locations of boundaries distribution (Cluster-CIS data): April 2007 - June 2009

for all events with

SW parameters

B1 and B6:

outer boundary of

outer RB

B2 and B5:

inner boundary of

outer RB

B3 and B4:

outer boundary of

inner RB

Running Average

Zoom

Psw: no ave. change

Vsw: decrease

Dips of outer RB to lower L shells


Zoom on Outer RB boundary dip distribution (Cluster-CIS data): April 2007 - June 2009

  • Outer boundary of outer RB:

  • - comes closer to Earth L=4

  • - then moves tailward L=6

  • Time scale: 50 days

  • Before boundary dip:

  • - Vsw from 430 to 540 km/sec

  • - Kp to 5

  • - Dst drop to -28 nT

  • - AE to 700 nT

  • - 2 peaks in Psw, 8 and 5 nPa

  • After boundary dip:

  • Vsw to 650 km/s

  • Kp to 5

  • Dst drop to -50 nT

  • AE to 800 nT

  • Psw at 3 nPa


Locations and width of slot region distribution (Cluster-CIS data): April 2007 - June 2009

slot widening:

during: * low Vsw * low AE


B2 distribution (Cluster-CIS data): April 2007 - June 2009 and B5:

inner boundary of

outer RB

B3 and B4:

outer boundary of

inner RB

B0:

Inner boundary of inner RB

Locations of boundaries

Observed at Double Star


  • Summary distribution (Cluster-CIS data): April 2007 - June 2009

  • During the period between April 2007 and June 2009 Cluster was deep in the radiation belts, coming to Earth at its perigee as close as L = 2.

  • During that period: Psw, Dst no change, Vsw decrease, Kp and AE decrease.

  • Dips of outer boundary of outer RB: comes closer to Earth at L=4, then moves tailwardat L=6. Before dip: peaks in Psw. After boundary dip: Vsw, Kp, AE increase, Dst drop, Psw no change. Always peaks in Psw right before the flux drop out.

  • Slot region widening (from 1.5 to 3 RE) during low activity, when Vsw and AE decrease: consistent with weaker inward radial diffusion, and also consistent with weaker local acceleration.

  • Boundaries determined from background measurements provide additional information on Radiation Belts, useful for Radiation Belts model development and validation.


Thank you

Thank you ! distribution (Cluster-CIS data): April 2007 - June 2009


ad