Morningside Pi2 Pulsation Observed in Space and on the Ground

Abstract. The characteristics of substorm-associated Pi2 pulsations observed by the SABRE coherent radar system during three separate case studies are presented. The SABRE field of view is well positioned to observe the differences between the auroral zone pulsation signature and that observed at mid-latitudes. During the first case study the SABRE field of view is initially in the eastward electrojet, equatorward and to the west of the substorm-enhanced electrojet current. As the interval progresses, the western, upward field-aligned current of the substorm current wedge moves westward across the longitudes of the radar field of view. The westward motion of the wedge is apparent in the spatial and temporal signatures of the associated Pi2 pulsation spectra and polarisation sense. During the second case study, the complex field-aligned and ionospheric currents associated with the pulsation generation region move equatorward into the SABRE field of view and then poleward out of it again after the third pulsation in the series. The spectral content of the four pulsations during the interval indicate different auroral zone and mid-latitude signatures. The final case study is from a period of low magnetic activity when SABRE observes a Pi2 pulsation signature from regions equatorward of the enhanced substorm currents. There is an apparent mode change between the signature observed by SABRE in the ionosphere and that on the ground by magnetometers at latitudes slightly equatorward of the radar field of view. The observations are discussed in terms of published theories of the generation mechanisms for this type of pulsation. Different signatures are observed by SABRE depending on the level of magnetic activity and the position of the SABRE field of view relative to the pulsation generation region. A twin source model for Pi2 pulsation generation provides the clearest explanation of the signatures observed.

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Pi2 pulsation simultaneously observed in theEandFregion ionosphere with the SuperDARN Hokkaido radar

Journal of Geophysical Research Space Physics ◽

10.1002/2012ja018585 ◽

2014 ◽

Vol 119 (5) ◽

pp. 3444-3462 ◽

Cited By ~ 9

Author(s):

M. Teramoto ◽

N. Nishitani ◽

V. Pilipenko ◽

T. Ogawa ◽

K. Shiokawa ◽

...

Keyword(s):

Pi2 Pulsation ◽

Hokkaido Radar

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Solar cycle dependence of Pi2 pulsation activity in the equatorial region of India

Journal of Atmospheric and Solar-Terrestrial Physics ◽

10.1016/s1364-6826(03)00118-4 ◽

2003 ◽

Vol 65 (8) ◽

pp. 941-945 ◽

Cited By ~ 2

Author(s):

Madhusudhan Rao ◽

S.V.S. Sarma

Keyword(s):

Solar Cycle ◽

Equatorial Region ◽

Pi2 Pulsation ◽

Pulsation Activity ◽

Cycle Dependence

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Pi2 pulsation polarization patterns on the U.K. sub-auroral magnetometer network (SAMNET)

Planetary and Space Science ◽

10.1016/0032-0633(90)90065-x ◽

1990 ◽

Vol 38 (5) ◽

pp. 589-602 ◽

Cited By ~ 60

Author(s):

T.K. Yeoman ◽

D.K. Milling ◽

D. Orr

Keyword(s):

Pi2 Pulsation

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Propagation property of transient MHD impulses in the Magnetosphere-Ionosphere System: The 2D model of the Pi2 pulsation

Geophysical Research Letters ◽

10.1029/2000gl000108 ◽

2001 ◽

Vol 28 (11) ◽

pp. 2161-2164 ◽

Cited By ~ 11

Author(s):

S. Fujita ◽

T. Mizuta ◽

M. Itonaga ◽

A. Yoshikawa ◽

H. Nakata

Keyword(s):

Propagation Property ◽

Pi2 Pulsation ◽

2D Model

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SABRE observations of structured ionospheric flows during substorm expansion phase onset

Annales Geophysicae ◽

10.1007/s00585-994-1027-y ◽

1994 ◽

Vol 12 (10/11) ◽

pp. 1027-1038

Author(s):

E. G. Bradshaw ◽

M. Lester ◽

T. B. Jones

Keyword(s):

Magnetic Activity ◽

Substorm Onset ◽

Field Of View ◽

Substorm Current Wedge ◽

Expansion Phase ◽

Pi2 Pulsation ◽

Pi2 Pulsations ◽

Generation Region ◽

Coherent Radar ◽

Current Wedge

Abstract. The irregularity velocity patterns observed by the SABRE coherent radar at substorm expansion phase onset, which is identified by magnetometer observations of Pi2 pulsations, are occasionally highly structured. In all the examples of structured velocity patterns examined, the SABRE viewing area is located at longitudes within the inferred substorm current wedge. Three types of structured velocity regime are apparent depending on the level of magnetic activity and the position of the radar viewing area relative to the substorm enhanced currents and the Pi2 pulsation generation region. Firstly, vortex-like velocity patterns are observed and these may be caused by the field-aligned currents associated with the substorm current wedge. Secondly, regions of equatorward velocity are also observed at times of substorm expansion phase onset moving longitudinally across the SABRE viewing area. The longitudinal movement is usually westward although an example of eastward motion has been observed. The phase velocity of these regions of equatorward flow is typically 1-3 km s-1. The observed equatorward velocities occur at the poleward edge or poleward of the background convection velocities observed by SABRE. These equatorward velocities may be related to the westward travelling surge and to the expansion (eastwards as well as westwards) of the brightening arc region at substorm onset. Thirdly, the flow rotates equatorward within the field of view but does not then appear to move longitudinally. These equatorward velocities may relate to the earthward surge of plasma from the magnetotail at substorm onset.

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Discrete Spectral Structure of Low-Latitude and Equatorial Pi2 Pulsation.

Journal of geomagnetism and geoelectricity ◽

10.5636/jgg.44.253 ◽

1992 ◽

Vol 44 (3) ◽

pp. 253-259 ◽

Cited By ~ 14

Author(s):

M. ITONAGA ◽

T.-I. KITAMURA ◽

O. SAKA ◽

H. TACHIHARA ◽

M. SHINOHARA ◽

...

Keyword(s):

Spectral Structure ◽

Low Latitude ◽

Pi2 Pulsation

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The First Pi2 Pulsation Observed by China Seismo-Electromagnetic Satellite

Remote Sensing ◽

10.3390/rs12142300 ◽

2020 ◽

Vol 12 (14) ◽

pp. 2300

Author(s):

Essam Ghamry ◽

Dedalo Marchetti ◽

Akimasa Yoshikawa ◽

Teiji Uozumi ◽

Angelo De Santis ◽

...

Keyword(s):

Local Time ◽

High Precision ◽

Particle Physics ◽

Low Frequency ◽

Night Time ◽

Ground Station ◽

Pi2 Pulsation ◽

Highly Correlated ◽

First Time ◽

Compressional Component

On 2 February 2018, the China Seismo-Electromagnetic Satellite (CSES) ZhangHeng 01 (ZH-01) was successfully launched, carrying on board, in addition to a suite of plasma and particle physics instruments, a high precision magnetometer package (HPM), able to observe the ultra-low frequency (ULF) waves. In this paper, a night time Pi2 pulsation observed by CSES is reported for the first time. This Pi2 event occurred on 3 September 2018, and began at 14:30 UT (02:37 magnetic local time), when the satellite was in the southern hemisphere between −49 and −13 magnetic latitude (MLAT). Kakioka (KAK) ground station in Japan detected the same Pi2 between 14:30–14:42 UT (23:30–23:42 local time). The Pi2 oscillations in the compressional, toroidal, and poloidal components at the CSES satellite and the H-component at the KAK station are investigated by estimating coherence, amplitude, and cross-phase. We noticed a high degree of similarity between the Pi2 event in the horizontal component at KAK and the ionospheric fluctuations in the compressional component at CSES. This high correlation indicated the magnetospheric source of the Pi2 event. In addition, Pi2 is exhibited clearly in the δBy component at CSES, which is highly correlated with the ground H component, so the Pi2 event could be explained by the Substorm Current Wedge (SCW). This interpretation is further confirmed by checking the compressional component of Van Allen Probe (VAP) B satellite inside the plasmasphere, which, for the first time, gives observational support for an earlier model. This ULF wave observation shows the consistency and reliability of the high precision magnetometer (HPM) equipped by two fluxgate magnetometers (FGM1 and FGM2) onboard CSES.

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