CASCADES-2: A View from THEMISJohn Bonnell

Space Sciences LaboratoryUC Berkeley

• What can THEMIS provide?• Multi-point magnetospheric observations of particles and fields.• Multi-point ground all-sky images and magnetometry.

• How do these observations complement the in situ multi-point CASCADES-2 particle and fields observations?• Provide meso-scale magnetospheric and ionospheric context.• Probably not direct conjunctive observations on the magnetospheric side, but electrodynamics may help with this:

•Meghan’s point on relative location of flows, flow boundaries, and FACs.• JWB’s point about FACs and shearing of B-field mapping in local time in latitudes of electrojet.

• Discussions at Dartmouth College, 29-30 Oct 2009 with C2 Science Team (Lessard esp.) and on-the-fly (in the plane home!) data analysis on the way home.• The change in B (dipolarization) suggests that McFadden’s study of DPs would be useful to consider.

Probe Xsm [Re]

Ysm [Re]

Zsm [Re]

Rxy [Re]

LATsm [deg]

11:00 UT

D (P3) -10.3 -1.9 -0.4 10.5 -2

E (P4) -11.1 -0.9 -0.8 11.1 -4

A (P5) -11.2 -0.8 -1.7 11.2 -9

11:30 UT

D (P3) -10.0 -2.1 -0.6 10.2 -3

E (P4) -10.8 -1.3 -0.9 10.9 -5

A (P5) -11.0 -1.1 -1.9 11.1 -10

Notes:1.Full Day Orbits in GSM (GSE rocked around Sun-Earth line with the dipole).2.C2 Flight Plots in SM (full rotation to dipole).

Full day orbits

1100 – 1130 UT

Notes:1.Field line traced using T96 (?) model.2.Footpoints traced to XXX altitude.3.LAT-LON grid is geographic.

Notes:1.THA 24-Hour Summary.

Notes:1.THA 6-Hour Summary (0600-1200 UT).2.What are the speckles that show up in the iSST and eSST data above the main flux peak between 1100 and 1200 UT (shows up, with different timing and duration on all three probes)?3.What is the line at fixed energy in the iSST data (also seen on all probes with different timing and durations and character)?

Notes:1.THD 6-Hour Summary (0600-1200 UT).

Notes:1.THE 6-Hour Summary (0600-1200 UT).

Notes:1.6-hour All-Probe FGM Summary (0600-1200 UT). 2.Is the large-amplitude (50-n T p2p!), ~25-min period magnetic fluctuation observed on THE geophysical or instrumental?

Notes:1.On-Board Spin Fit (3-s resolution) B- and E-field.2.DSL coordinates (Despun Spacecraft, z along L), ~ GSE.3.Spin axis E deleted (SC potential contamination).

B [n

T]

E [m

V/m

]THA

THD

THE

Notes (Panels REORDERED A-E-D from A-D-E!):1.On-Board Spin Fit (3-s resolution) B- and E-field.2.DSL coordinates (Despun Spacecraft, z along L), ~ GSE.3.Spin axis E deleted (SC potential contamination).4.B-field direction angles in DSL:

1. Phi is azimuth angle:1. (0 – 360 deg; 0 is

Sunward, 90 dusk, 180 tailward, 270 dawn).

2. Theta is polar angle:1. (0-180 deg; 0 parallel to

DSL Z; 180 anti-parallel to DSL Z).

5.Largest-amplitude variations in B-angles are slowly-varying, and so are poor-resolution timing markers!!!6.Higher-frequency variations in B-angles are poorly correllated (by eye) between probes, and so are also poor timing markers!!!

THA

THE

THD

Notes:1.On-Board Spin Fit (3-s resolution) B- and E-field.2.DSL coordinates (Despun Spacecraft, z along L), ~ GSE.3.Spin axis E deleted (SC potential contamination).

THA

THD

THE

Notes:1.4 samp/s THE-FGM FGL data in GSE.2.Spectral Analysis parameters:

1. 32-point FFT (1/8-Hz res).2. 4 spec avg’d, half-lapped (20-s

res).3. +/-5-pt running MEDIAN

removed from signals before spectra computed (2.5-s MEDIAN window; may impact spectral density below .4-Hz (?) by high-pass filtering).

3.Residual spin tone and harmonics (N*0.33-Hz) visible in X and Y components (~spin plane); minimal in Z (~spin axis).4.Color bars are close, but not identical, so beware (X,Y max is higher than Z).5.Really should be run in FAC coordinates, not GSE, to get transverse and compressional components!

Notes (data from THA):1.Spin-resolution (3-s) iESA energy spectra (integrated over angles).2.Ion density estimate (iESA only; no SST).3.Ion velocity estimate (iESA only; no SST).4.Offset issue with EFS Ex (sunward offset not being handled/removed correctly?).5.FGS data, as before.6.Flows during dipolarization event around 1100 UT are weak (~ 50 km/s, not well-organized), but there are significant E and B fluctuations, 7.Compare to the correlation between Vi and Ey at ~1155 UT, for example, which may be a better example of a Earthward flow burst (fast flow, BBF, what have you)!8.Vi != ExB at dipolarization event, as might be expected, due to propagating current sheet (Hall effects!).

Notes:Space Sci Rev, DOI 10.1007/s11214-008-9380-xThe THEMIS Array of Ground-based Observatoriesfor the Study of Auroral Substorms, Mende et al. (2008) -- “Fig. 5 Map of North America with the GBO station names, locations and their approximate fields of view ofthe all-sky cameras. Magnetic latitudes are shown with dashed lines. Meridians of local magnetic midnightat 03, 06, 09, and 12 UT are also indicated.”

http://www.igpp.ucla.edu/public/THEMIS/SCI/Pubs/2008_Refereed/mende_ssr_onlinefirst.pdf

Notes:1.24-hour high-lat GBO GMAG H-component.2.Coordinates:

1. H = Horizontal (+N, -S).2. D = Declination (+E, -W).3. Z = Vertical (+Down, -Up).

3.Negative Bays at ~1100 UT:1. BETT2. HLMS3. CIGO4. POKR5. FYKN6. KAKO7. EAGL8. INUV

4.Westward E-Jet present above AK.

Notes:1.24-hour high-lat GBO GMAG Z-component.2.Coordinates:

1. H = Horizontal (+N, -S).2. D = Declination (+E, -W).3. Z = Vertical (+Down, -Up).

3.+Z deflections:1. KAKO2. INUV3. SNAP4. RANK

4.-Z deflections:1. EAGL2. KIAN (?)3. BETT4. FSMI

5.Westward E-Jet at ~70 MLAT over AK?

Notes:1.24-hour high-lat GBO GMAG D-component.2.Coordinates:

1. H = Horizontal (+N, -S).2. D = Declination (+E, -W).3. Z = Vertical (+Down, -Up).

Notes:1.GBO ASI Mosaic2.http://themis.ssl.berkeley.edu/gbo/display.py?date=2009.03.20&view_type=keograms&submit=Start