Transcript ULF waves and transients at very high latitudes: Possible

A High-Latitude
Window to Geospace
Dynamics: PENGUIn
Pilipenko V.A.
PENGUIn and other national Antarctic arrays
>30 countries
Flux-gate magnetometers
Search-coil magnetometers
+ auroral imagers, riometers, VLF antennas, …
Antarctic
SuperDARN
Radars and
Magnetometers
Identification of projections of boundary
magnetospheric domains from ground
The ULF discriminant of the magnetospheric boundary domains
has not been found yet, though many types of “cusp-related”
pulsations: IPCL, Pc5, Pc3, were reported. Validation of the ground
technique can be made with the use of SuperDARN radars.
As an example, we have verified this approach using small
magnetometer array at Svalbard and SuperDARN radar at
Hanskalsarmi for cusp-related Pc3 pulsations.
“Cusp” Pc3 waves at Svalbard
array on 2008/02/21
Radar: cusp equatorward boundary at
~76°-77°, beyond magnetometer array.
Latitudinal distribution of Pc3 power is
shifted to lower latitudes: peak at 75.3°!
ULF wave power maximum is shifted
~3° southward from the equatorward
cusp boundary!
In early studies, the cusp proper was suggested as a
conduit of the upstream waves and source of dayside Pc3
pulsations?
“Cusp Pc3 pulsations” are not related to the cusp
proper!? A physical mechanism of cusp-related Pc3 ?
Coupling between the magnetotail and polar cap boundary phenomena
(PBI, BBF, Pi1/2, ..)
PBI is not only a manifestation of bursty
magnetotail activity (BBF, …), but has
been found to be a trigger of the substorm
onset [Nishimura, 2010]!
Is there a ground magnetic image of PBI
activity? Global ULF mode (~25 min)
[Lyons, 2002], Pi2 [Sutcliffe, 2003]?
What is the correspondence between the
magnetotail fast flows, PBI, Alfvenic
aurora, and Pi1B wave burst?
Fine time/spatial structure of substorm onset from multi-instrument
Antarctic observations: 5 minutes before and after
Initial substorm brightening can be provided by
Alfven wave-driven aurora, correlated with Pi1B
pulsations. Pi1B can be used both for timing of
onset, and the location of the substorm “epicenter”.
Auroral kilometric radiation (AKR) during onset
develops explosively above a preexisting (~1–3 m)
low-altitude AKR source. ‘‘AKR breakup’’ suggests
an abrupt (4 orders in 30 s!) formation of a new
auroral acceleration region (AAR). The development
of the low-altitude AAR is a necessary condition for
the bursty ignition of high-altitude AAR.
Can this fine structure of onset be revealed from
ground ULF observations?
Example of the fine structure of the substorm onset
and related ULF activity [Morioka et al., 2008]
High latitude multi-instrument observations:
- ULF Pi2 and Pi1B
- AKR (ground array) [LaBelle, 2010]!
- VLF, riometer, auroral imager,….
Location of the substorm “epicenter”
Onset location can be determined from ground data:
- Pi2 current structure
- Pi1 burst location
- Pc1 polarization goniometer
- AKR triangulation
Pi1 burst location determined
by the emission tomography
method from seismology)
ULF onset (before s/s onset!) times from CARISMA (AWESOME) [Rae, 2004]
advanced version of AWESOME algorithm
TCV
TCV = well-known and most easily evident signature of the impulsive SW - magnetosphere
interaction. TCV is known to be accompanied by burst of Pc1 waves.
Have the TCV-related Pc1 bursts, SSC-related Pc1 bursts, and ordinary EMIC waves the
same physical mechanism?
TCV as a local particle
accelerator: Is there a TCVrelated spot of proton or electron
aurora, or riometer burst?
Specific High-latitude ULF Waves and Transients
The virtue of the Antarctic array of stations is the opportunity to monitor ULF wave activity along a transpolar chain from mid-latitudes deep into the polar cap. This makes it possible to examine the wave coupling
between different regions of the magnetosphere. Polar cap is not a quiet place:
Monochromatic Pc3 waves deep inside the polar cap [De Lauretis, 2005]
Polar cap Pi3 pulsations
Specific polar cap long-period variations (T~4-20 min) have been revealed unambiguously with
the cross-spectral analysis of 2D distributions of wave parameters from Antarctic stations
[Yagova et al., 2002,2004; Pilipenko et al., 2004]. Picap3 variations are independent of cusp and
auroral pulsations (not Pc5!): These polar cap-associated pulsations are coherent within the polar
cap night side, and low coherent with auroral and/or cusp disturbances.
The polar cap Picap3 signals are probably related to waves/transients in the tail lobes or global
oscillations of night-side magnetosphere?
Example of Pi3 pulsations in the
polar cap (P5, P6)
Non-conjugate long-period Pi3 waves in the polar caps
Antarctic magnetometers (P5, P6) indicate the occurrence of specific Pi3 pulsations in the
polar cap with periods ~20 min.
Arctic polar cap magnetometers (ALE, THL) reveal no signature of simultaneous
oscillations!?
Probable Geophysical Interpretation
Alfven-type
mode
In the high-latitude magnetosphere the propagation of Alfven waves can be significantly affected by local
variations in the B geometry:
 An Alfvenic quasi-resonator may occur due to partial AW reflection from a region with rapid changes of
B geometry [Pilipenko, 2005] or with high -value and curvature [Mager, 2009]. Wave branches in a high-
plasma in a curved B shows the occurrence of a non-propagation band for the Alfven-type mode.
 May oscillations of only a part of field line are excited? Alfven quasi-resonator along extended field lines
between polar ionosphere & current sheet/magnetopause? Non-conjugate oscillations?
 However, predictions of those models should be further verified, both experimentally and numerically with
more realistic models and high-latitude conjugate observations.
Support for the upcoming satellite and balloon campaigns
BARREL (Balloon Array for RBSP Relativistic Electron Losses) is
a study of losses from Earth's radiation belts. BARREL will consist
of two Antarctic balloon campaigns conducted in 2012 and 2013.
During each campaign, 20 small balloon payloads will be
launched from the SANAE IV and the Halley Bay to an altitude of
~30 km with scintillator to measure the bremsstrahlung X-rays
produced by precipitating relativistic electrons.
Can EMIC waves damp magnetospheric relativistic electrons?
Upcoming satellite missions:
 RBSP (NASA)
 Orbitals (Canada)
 Relec, Resonance (Russia)
National Institute of Polar Research
(Japan)
Syowa Station:
- Magnetic variation with a fluxgate magnetometer (1-s) and unmanned
low power magnetometer network (Skallen, Cape Omega, H100, Dome-F);
- Auroral spectroscopic observation: ASC imager (557.7, 630.0, 427.8
nm), All-sky TV camera, Multi-color meridian scanning photometer,
- Imaging 1 Hz Riometer (8 x 8 dipole antenna) which covers the area of
180km x 180km at D region altitude;
- 1-100Hz Electromagnetic Wave Observation;
- SuperDARN radar (Syowa-South and Syowa-East);
Conjugate observation at Iceland at Syowa, including fluxgate and
induction magnetometers, imaging riometer, VLF receiver, all-sky CCD
imager at stations Husafell, Tjornes, and Aedey.
British Antarctic Survey
(BAS)
operates 4 stations throughout the year in Antarctic:
Bird Island,
King Edward Point,
Rothera,
Halley,
+ biological research center & logistics facilities
+ Ny-Ålesund research station in the Arctic.
Various instruments for Sun Earth
Connections Programme
Low Power Magnetometers (1 sec) operate
unmanned all year round
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