Large‐scale observations of a subauroral polarization stream by midlatitude SuperDARN radars: Instantaneous longitudinal velocity variations

Clausen, L. B. N.; Baker, J. B.; Ruohoniemi, J. M.; Greenwald, R. A.; Thomas, E. G.; Shepherd, Simon; Talaat, E. R.; Bristow, W. A.; Zheng, Yihua; Coster, A. J.; Sazykin, S.

doi:10.1029/2011ja017232

Cited by 63 publications

(86 citation statements)

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“…Infrastructure (MSI) programme (see, e.g., Clausen et al, 2012). By the time of the radar data that are presented in this paper were collected, the mid-latitude SuperDARN coverage reached across North America in an unbroken chain of interlocking radar field-of-view.…”

Section: Instruments and Methodsmentioning

confidence: 99%

“…5a). Equatorward of it, the Christ- consistent with a moderate sub-auroral polarisation stream (SAPS) (Foster and Burke, 2002;Clausen et al, 2012;Kunduri et al, 2012). Figure 3d shows the SAPS velocities extended along the main trough just south of the radars in Prince George and Saskatoon and adjacent to the CHAIN GPS receiver in Ministik Lake near Edmonton (EDMC in Fig.…”

Section: Solar Wind Conditions and The Ionospheric Response At High Lmentioning

confidence: 99%

“…The TEC rate can be used as an index to monitor ionospheric irregularities (see e.g., Pi et al, 1997;Beach and Kintner, 1999;Jakowski et al, 2012). S 4 scintillation index proxies have been used at low latitudes (Du et al, 2001;Dandekar and Groves, 2004). In this paper, a proxy for σ is obtained from GPS receivers recording 1-Hz data to complement availability of σ that is often enhanced at high latitudes (Prikryl et al, 2011(Prikryl et al, , 2013.…”

Section: Introductionmentioning

confidence: 99%

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GPS phase scintillation and proxy index at high latitudes during a moderate geomagnetic storm

et al. 2013

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The amplitude and phase scintillation indices are customarily obtained by specialised GPS Ionospheric Scintillation and TEC Monitors (GISTMs) from L1 signal recorded at the rate of 50 Hz. The scintillation indices S₄ and σ_Φ are stored in real time from an array of high-rate scintillation receivers of the Canadian High Arctic Ionospheric Network (CHAIN). Ionospheric phase scintillation was observed at high latitudes during a moderate geomagnetic storm (Dst = −61 nT) that was caused by a moderate solar wind plasma stream compounded with the impact of two coronal mass ejections. The most intense phase scintillation (σ_Φ ~ 1 rad) occurred in the cusp and the polar cap where it was co-located with a strong ionospheric convection, an extended tongue of ionisation and dense polar cap patches that were observed with ionosondes and HF radars. At sub-auroral latitudes, a sub-auroral polarisation stream that was observed by mid-latitude radars was associated with weak scintillation (defined arbitrarily as σ_Φ < 0.5 rad). In the auroral zone, moderate scintillation coincided with auroral breakups observed by an all-sky imager, a riometer and a magnetometer in Yellowknife. To overcome the limited geographic coverage by GISTMs other GNSS data sampled at 1 Hz can be used to obtain scintillation proxy indices. In this study, a phase scintillation proxy index (delta phase rate, DPR) is obtained from 1-Hz data from CHAIN and other GPS receivers. The 50-Hz and 1-Hz phase scintillation indices are correlated. The percentage occurrences of σ_Φ > 0.1 rad and DPR > 2 mm s⁻¹, both mapped as a function of magnetic latitude and magnetic local time, are very similar

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Section: Instruments and Methodsmentioning

confidence: 99%

Section: Solar Wind Conditions and The Ionospheric Response At High Lmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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GPS phase scintillation and proxy index at high latitudes during a moderate geomagnetic storm

et al. 2013

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“…In past studies patches have been tracked using data from coherent scatter radars and incoherent scatter radars (ISR) as well as ionosondes; however the patches themselves have been identified by humans (Clausen et al, 2012;Grant et al, 1995;Mori et al, 2012;Oksavik et al, 2006;Pedersen et al, 1998). An algorithm for detecting patches automatically from Dynamics Explorer 2 satellite data has also been developed (Coley and Heelis, 1995).…”

Section: R Burston Et Al: Automated Identification and Tracking Of mentioning

confidence: 99%

Automated identification and tracking of polar-cap plasma patches at solar minimum

et al. 2014

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Abstract.A method of automatically identifying and tracking polar-cap plasma patches, utilising data inversion and feature-tracking methods, is presented. A well-established and widely used 4-D ionospheric imaging algorithm, the Multi-Instrument Data Assimilation System (MIDAS), inverts slant total electron content (TEC) data from groundbased Global Navigation Satellite System (GNSS) receivers to produce images of the free electron distribution in the polar-cap ionosphere. These are integrated to form vertical TEC maps. A flexible feature-tracking algorithm, TRACK, previously used extensively in meteorological storm-tracking studies is used to identify and track maxima in the resulting 2-D data fields. Various criteria are used to discriminate between genuine patches and "false-positive" maxima such as the continuously moving day-side maximum, which results from the Earth's rotation rather than plasma motion. Results for a 12-month period at solar minimum, when extensive validation data are available, are presented. The method identifies 71 separate structures consistent with patch motion during this time. The limitations of solar minimum and the consequent small number of patches make climatological inferences difficult, but the feasibility of the method for patches larger than approximately 500 km in scale is demonstrated and a larger study incorporating other parts of the solar cycle is warranted. Possible further optimisation of discrimination criteria, particularly regarding the definition of a patch in terms of its plasma concentration enhancement over the surrounding background, may improve results.

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“…The subauroral polarization stream (SAPS) is one of the interesting and important features of the magnetosphereionosphere-thermosphere coupling processes in the subauroral region, representing the rapid westward plasma flow predominantly in the dusk and premidnight sector (16-24 magnetic local time, MLT) (e.g., Galperin et al, 1974;Spiro et al, 1979;Anderson et al, 1991Anderson et al, , 1993Anderson et al, , 2001Yeh et al, 1991;Fejer and Scherliess, 1998;Scherliess and Fejer, 1998;Rowland and Wygant, 1998;Wygant et al, 1998;Ridley et al, 2002;Foster and Vo, 2002;Garner et al, 2004;Figueiredo et al, 2004;Liemohn et al, 2005;Jensen and Fejer, 2007;Zheng et al, 2008;Erickson et al, 2010Erickson et al, , 2011Clausen et al, 2012;Mishin, 2013). Two types of plasma flows have been classified in the literature: (1) polarization jets (PJ) (Galperin et al, 1974) or subauroral ion drifts (SAIDS) (Spiro et al, 1979), featured as more intense (∼ 1000 m s −1 ) and latitudinally confined (≤ 1 • latitude) plasma flow; and (2) a wider latitudinal extent and longer duration of plasma flow (Yeh et al, 1991).…”

Section: Introductionmentioning

confidence: 99%

The spatial distribution of region 2 field-aligned currents relative to subauroral polarization stream

et al. 2014

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Abstract. To test the current-generation model of subauroral polarization stream (SAPS), we have investigated the relative positions of field-aligned currents (FACs) with respect to SAPS in a statistical way by using CHAMP (CHAllenging Minisatellite Payload) and DMSP (Defense Meteorological Satellite Program) satellite observations as well as model simulations. Comparative studies have been performed for consecutive CHAMP observations in different magnetic local time (MLT) sectors with respect to SAPS. The latitude of the peak westward zonal wind deduced from CHAMP measurements has been used to represent the location of the SAPS peak. Both the density and the sheet current strength of R2 (region 2) FACs are enhanced when SAPS occur. Subsequently R2 FACs decay in intensity and correspondingly the centers retreat poleward. The latitudes of the center of the R2 FAC, small-and medium-scale FACs, and SAPS shift equatorward with increasing MLT. The SAPS peaks are located between R2 and R1 (region 1) FAC peaks in all MLT bins under study. The SAPS peaks are closer to R2 centers in the later MLT sectors. The peaks of small-and mediumscale FACs are located poleward of SAPS, mainly in the upward R1 FACs region. The upward R1 FACs are partly closed by the downward R1 FACs in the dawn-morning sector. Based on model simulation, when R2 shifts equatorward to the subauroral region, the plasma flow also shifts equatorward with its peak located poleward of that of R2 FACs. Both the model and observations provide evidence that SAPS behave as caused by a magnetospheric current source.

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Large‐scale observations of a subauroral polarization stream by midlatitude SuperDARN radars: Instantaneous longitudinal velocity variations

Cited by 63 publications

References 45 publications

GPS phase scintillation and proxy index at high latitudes during a moderate geomagnetic storm

GPS phase scintillation and proxy index at high latitudes during a moderate geomagnetic storm

Automated identification and tracking of polar-cap plasma patches at solar minimum

The spatial distribution of region 2 field-aligned currents relative to subauroral polarization stream

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