On the importance of interplanetary magnetic field ∣By∣ on polar cap patch formation

Zhang, Q.-H.; Zhang, B.-C.; Liu, R.-Y.; Dunlop, M. W.; Lockwood, Mike; Moen, J.; Yang, Huigen; Hu, Hongqiao; Liu, S.-L.; McCrea, I. W.; Lester, M.

doi:10.1029/2010ja016287

Cited by 123 publications

(103 citation statements)

References 79 publications

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“…5d, where fast flows of >~1500 m/s are predominantly seen during large |By| and small |Bz|. Under a large IMF By condition, it has been observed that mesoscale flows in the cusp region propagate poleward, and this has been suggested to be due to large tension force in dayside reconnection under large IMF |By| (Sandholt et al 2004;Lockwood et al 2005;Rinne et al 2010;Zhang et al 2011Zhang et al , 2013b. Combining with our observation, these mesoscale flows may move far away from the noon meridian and then propagate into the polar cap.…”

Section: Imf By and Bz Dependencesupporting

confidence: 59%

“…It is known that for large, negative By, the boundary between dawn and dusk convection cells is shifted toward dawn in the southern hemisphere (Reiff and Burch 1985;Lyons et al 1996) and toward dusk in the northern hemisphere (Weimer 2005). Additionally, the previous case studies have shown the IMF By-related formation of polar cap patches (Lockwood et al 2005;Zhang et al 2011Zhang et al , 2013b. In our study, we statistically showed that the departing points of these patches from the poleward boundary of auroral oval are associated with IMF By, and moreover, the airglow patches that depart at <9 MLT are with strong negative By.…”

Section: Resultsmentioning

confidence: 99%

“…Recently, Goodwin et al (2015) used SWARM data to document the intake of solar-EUV plasma through fast flow channels. Those fast flows are also associated with poleward moving auroral forms (PMAFs), which are considered to be an ionospheric signature of localized dayside magnetic reconnection and flux transfer events (FTEs) (Moen et al 1995;Provan et al 1998McWilliams et al 2000;Milan et al 2000;Sandholt and Farrugia 2003;Lockwood et al 2005;Carlson et al 2006;Zhang et al 2011Zhang et al , 2013b. PMAFs initiate near the poleward boundary of the dayside auroral oval and then propagate poleward before fading away (Lorentzen et al 2010).…”

Section: Introductionmentioning

confidence: 99%

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Analysis of close conjunctions between dayside polar cap airglow patches and flow channels by all-sky imager and DMSP

et al. 2016

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Recent imager and radar observations in the nightside polar cap have shown evidence that polar cap patches are associated with localized flow channels. To understand how flow channels propagate from the dayside auroral oval into the polar cap, we use an all-sky imager in Antarctica and DMSP (F13, F15, F16, F17 and F18) to determine properties of density and flows associated with dayside polar cap patches. We identified 50 conjunction events during the southern winter seasons of 2007-2011. In a majority (45) of events, longitudinally narrow flow enhancements directed anti-sunward are found to be collocated with the patches, have velocities (up to a few km/s) substantially larger than the large-scale background flows (~500 m/s) and have widths comparable to patch widths (~400 km). While the patches start with poleward moving auroral forms (PMAFs) as expected, many PMAFs propagate azimuthally away from the noon over a few hours of MLT, resulting in formation of polar cap patches quite far away from the noon, as early as ~6 MLT. The MLT separation from the noon is found to be proportional to the IMF |By|. Fast polar cap flows of >~1500 m/s are predominantly seen during large IMF |By| and small |Bz|. The presence of fast, anti-sunward flow channels associated with the polar cap patches suggests that the flow channels form in the dayside auroral oval through transient reconnection and can be the source of flow channels propagating into the polar cap.

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Section: Imf By and Bz Dependencesupporting

confidence: 59%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Analysis of close conjunctions between dayside polar cap airglow patches and flow channels by all-sky imager and DMSP

et al. 2016

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“…7a). These suggest that the transient reconnection (FTE) leads to the erosion of the OCB equatorward to a region of higher density plasma (the solar EUV ionized plasma), followed by poleward relaxation of that boundary carrying with it the high density plasma accelerated into the polar flow (Lockwood and Carlson, 1992;Zhang et al, 2011). The plasma flow has a poleward component for most of the time between 09:00 UT and 12:00 UT (see the fourth panel of Fig.…”

Section: Eiscat Measurementsmentioning

confidence: 99%

Coordinated Cluster/Double Star and ground-based observations of dayside reconnection signatures on 11 February 2004

et al. 2011

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Abstract.A number of flux transfer events (FTEs) were observed between 09:00 and 12:00 UT on 11 February 2004, during southward and dawnward IMF, while the Cluster spacecraft array moved outbound through the northern, highaltitude cusp and dayside high-latitude boundary layer, and the Double Star TC-1 spacecraft was crossing the dayside low-latitude magnetopause into the magnetosheath south of the ecliptic plane. The Cluster array grazed the equatorial cusp boundary, observing reconnection-like mixing of magnetosheath and magnetospheric plasma populations. In an adjacent interval, TC-1 sampled a series of sometimes none standard FTEs, but also with mixed magnetosheath and magnetospheric plasma populations, near the magnetopause crossing and later showed additional (possibly turbulent) activity not characteristic of FTEs when it was situated deeper in the magnetosheath. The motion of these FTEs are analyzed in some detail to compare to simultaneous, poleward-moving plasma concentration enhancements recorded by EISCAT Svalbard Radar (ESR) and "polewardmoving radar auroral forms" (PMRAFs) on the CUTLASS Finland and Kerguelen Super Dual Auroral Radar Network (SuperDARN) radar measurements. Conjugate SuperDARN observations show a predominantly two-cell convection pattern in the Northern and Southern Hemispheres. The results are consistent with the expected motion of reconnected magnetic flux tubes, arising from a predominantly sub-solar reconnection site. Here, we are able to track north and south in closely adjacent intervals as well as to map to the corresponding ionospheric footprints of the implied flux tubes and demonstrate these are temporally correlated with clear ionoCorrespondence to: Q.-H. Zhang (zhangqinghe@pric.gov.cn) spheric velocity enhancements, having northward (southward) and eastward (westward) convected flow components in the Northern (Southern) Hemisphere. The durations of these enhancements might imply that the evolution time of the FTEs is about 18-22 min from their origin on magnetopause (at reconnection site) to their addition to the magnetotail lobe. However, the ionospheric response time in the Northern Hemisphere is about 2-4 min longer than the response time in the Southern Hemisphere.

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“…(Zhang et al, 2017), but, if they appear only in 630.0 nm keogram ( Figure 1B), so called polar cap patches (e.g., Sato et al, 1998;Zhang et al, 2011Zhang et al, , 2013aZhang et al, ,b, 2016Hosokawa et al, 2012). Whenever, these structures meet the GNSS signals, they give rise to moderate amplitude and phase scintillation (Hosokawa et al, 2014), especially for polar cap hot patches (Zhang et al, 2017).…”

Section: Fixed Boundary Auroral Emissions (Fbae)mentioning

confidence: 99%

The Behaviors of Ionospheric Scintillations Around Different Types of Nightside Auroral Boundaries Seen at the Chinese Yellow River Station, Svalbard

Priyadarshi

Zhang

et al. 2018

Front. Astron. Space Sci.

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Dynamical nightside auroral structures are often observed by the all sky imagers (ASI) at the Chinese Yellow River Station (CYRS) at Ny-Ålesund, Svalbard, located in the polar cap near poleward edge of the nightside auroral oval. The boundaries of the nightside auroral oval are stable during quiet geomagnetic conditions, while they often expand poleward and pass through the overhead area of CYRS during the substorm expansion phase. The motions of these boundaries often give rise to strong disturbances of satellite navigations and communications. Two cases of these auroral boundary motions have been introduced to investigate their associated ionospheric scintillations: one is Fixed Boundary Auroral Emissions (FBAE) with stable and fixed auroral boundaries, and another is Bouncing Boundary Auroral Emissions (BBAE) with dynamical and largely expanding auroral boundaries. Our observations show that the auroral boundaries, identified from the sharp gradient of the auroral emission intensity from the ASI images, were clearly associated with ionospheric scintillations observed by Global Navigation Satellite System (GNSS) scintillation receiver at the CYRS. However, amplitude scintillation (S 4 ) and phase scintillation (σ φ ) respond in an entirely different way in these two cases due to the different generation mechanism as well as different IMF (Interplanetary Magnetic Field) condition. S 4 and σ φ have similar levels around the FBAE, while σ φ was much stronger than S 4 around BBAE. The BBAE were associated with stronger particle precipitation during the substorm expansion phase. IU/IL, appeared to be a good indicator of the poleward moving auroral structures during the BBAE as well as FBAE.

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On the importance of interplanetary magnetic field ∣B_y∣ on polar cap patch formation

Cited by 123 publications

References 79 publications

Analysis of close conjunctions between dayside polar cap airglow patches and flow channels by all-sky imager and DMSP

Analysis of close conjunctions between dayside polar cap airglow patches and flow channels by all-sky imager and DMSP

Coordinated Cluster/Double Star and ground-based observations of dayside reconnection signatures on 11 February 2004

The Behaviors of Ionospheric Scintillations Around Different Types of Nightside Auroral Boundaries Seen at the Chinese Yellow River Station, Svalbard

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