Drifting airglow patches in relation to tail reconnection

Lorentzen, D. A.; Shumilov, N.; Moen, J.

doi:10.1029/2003gl017785

Cited by 63 publications

(95 citation statements)

References 21 publications

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“…From around 18:30 UT to 23:00 UT, we find a sequence of six inverted integral signs in the keogram (denoted by A-F in Fig. 1a), which is a feature of polar cap patches travelling across the FOV from north to south (Lorentzen et al 2004;Moen et al 2007). From 20:00 UT to 22:00 UT, the auroral boundary moved poleward, stopped and retreated equatorward several times, which is an auroral signature of transient tail reconnection followed by boundary relaxation (Lorentzen et al 2004;Cowley & Lockwood 1992;Moen et al 2007).…”

Section: Observationsmentioning

confidence: 99%

“…1a), which is a feature of polar cap patches travelling across the FOV from north to south (Lorentzen et al 2004;Moen et al 2007). From 20:00 UT to 22:00 UT, the auroral boundary moved poleward, stopped and retreated equatorward several times, which is an auroral signature of transient tail reconnection followed by boundary relaxation (Lorentzen et al 2004;Cowley & Lockwood 1992;Moen et al 2007). Several polar cap patches crossed the open/closed magnetic field line boundary and exited into the nightside auroral oval, where they changed their status to auroral blobs (Crowley et al 2000).…”

Section: Observationsmentioning

confidence: 99%

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GPS scintillation effects associated with polar cap patches and substorm auroral activity: direct comparison

Jin

Moen

Miloch

2014

J. Space Weather Space Clim.

102

136

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We directly compare the relative GPS scintillation levels associated with regions of enhanced plasma irregularities called auroral arcs, polar cap patches, and auroral blobs that frequently occur in the polar ionosphere. On January 13, 2013 from Ny-Å lesund, several polar cap patches were observed to exit the polar cap into the auroral oval, and were then termed auroral blobs. This gave us an unprecedented opportunity to compare the relative scintillation levels associated with these three phenomena. The blobs were associated with the strongest phase scintillation (r / ), followed by patches and arcs, with r / up to 0.6, 0.5, and 0.1 rad, respectively. Our observations indicate that most patches in the nightside polar cap have produced significant scintillations, but not all of them. Since the blobs are formed after patches merged into auroral regions, in space weather predictions of GPS scintillations, it will be important to enable predictions of patches exiting the polar cap.

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Section: Observationsmentioning

confidence: 99%

Section: Observationsmentioning

confidence: 99%

GPS scintillation effects associated with polar cap patches and substorm auroral activity: direct comparison

Jin

Moen

Miloch

2014

J. Space Weather Space Clim.

102

136

View full text Add to dashboard Cite

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“…After formation by ionospheric cusp dynamics, the patches follow the convection pattern across the pole from day to night and are pulled into the nightside oval on exiting the polar cap (Buchau et al, 1983;Weber et al, 1984;Lorentzen et al, 2004). Several observation techniques have been used for patch studies, such as direct electron density measurements by ionosonde (Buchau et al, 1983;Dandekar and Bullett, 1999;Dandekar, 2002), incoherent scatter radar (e.g.…”

Section: Introductionmentioning

confidence: 99%

“…Several observation techniques have been used for patch studies, such as direct electron density measurements by ionosonde (Buchau et al, 1983;Dandekar and Bullett, 1999;Dandekar, 2002), incoherent scatter radar (e.g. Valladares et al, 1994Valladares et al, , 1996Valladares et al, , 1998Carlson et al, 2002Carlson et al, , 2004Carlson et al, , 2006Lockwood and Carlson, 1992;Lockwood et al, 2005aLockwood et al, , 2005bOksavik et al, 2006a), and ionospheric tomography (Walker et al, 1999;Pryse et al, 2004), 630.0-nm airglow intensity that is proportional to electron density (Weber et al, 1984;Harris, 1995, 1996;McEwen et al, , 2004Lorentzen et al, 2004), and more indirectly by HF coherent scatter radars of the SuperDARN network (Rodger et al, 1994;Ogawa et al, 1998;Rodger and Graham, 1996;Milan et al, 2002Milan et al, , 2005Oksavik et al, 2006a). The latter technique does not provide a measurement of the electron density but gives the backscatter power from irregularities on electron density gradient associated E×B drift instability (Tsunoda, 1988;Chaturvedi and Ossakow, 1981).…”

Section: Introductionmentioning

confidence: 99%

EISCAT observations of plasma patches at sub-auroral cusp latitudes

et al. 2006

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Abstract.A sequence of 3 patches of high-density (10 12 m −3 ) cold plasma on a horizontal scale-size of 300-700 km was observed near magnetic noon by the EISCAT VHF radar above Svalbard on 17 December 2001. The patches followed a trajectory towards the cusp inflow region. The combination of radar and all-sky observations demonstrates that the patches must have been segmented equatorward of the cusp/cleft auroral display, and hence their properties had not yet been influenced by cusp particle showers and electrodynamics on open flux tubes. The last patch in the sequence was intersected by radio tomography observations, and was found to be located adjacent to a broader region of the same high electron density further south. The patches occurred under moderately active conditions (Kp=3) and the total electron content (TEC) of the high-density plasma was 45 TEC units. The train of patches appeared as a segmentation of the tongue of ionization. The sequence of patches occurred in association with a sequence of flow bursts in the dusk cell return flow. It is proposed that reconnection driven pulsed convection is able to create sub-auroral patches in the region where high density mid-latitude plasma is diverted poleward toward the cusp. It is the downward Birkeland current sheet located at the equatorward boundary of the flow disturbance that represents the actual cutting mechanism.

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“…Latitudinally localised soft particle precipitation was suggested as the source mechanism (Rino et al, 1983) whilst modelling predicted that a polar cap patch could exit the polar cap and reconfigure to form a boundary blob (Robinson et al, 1985). Patches have been observed leaving the polar cap (Pedersen et al, 2000;Moen et al, 2007;Lorentzen et al, 2004) and experimental evidence for the reconfiguration of a polar patch into an evening-time boundary blob has been presented .…”

Section: Introductionmentioning

confidence: 97%

Modulation of nightside polar patches by substorm activity

2009

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Abstract.Results are presented from a multi-instrument study showing the influence of geomagnetic substorm activity on the spatial distribution of the high-latitude ionospheric plasma. Incoherent scatter radar and radio tomography measurements on 12 December 2001 were used to directly observe the remnants of polar patches in the nightside ionosphere and to investigate their characteristics. The patches occurred under conditions of IMF B z negative and IMF B y negative. They were attributed to dayside photoionisation transported by the high-latitude convection pattern across the polar cap and into the nighttime European sector. The patches on the nightside were separated by some 5 • latitude during substorm expansion, but this was reduced to some 2 • when the activity had subsided. The different patch separations resulted from the expansion and contraction of the high-latitude plasma convection pattern on the nightside in response to the substorm activity. The patches of larger separation occurred in the antisunward cross-polar flow as it entered the nightside sector. Those of smaller separation were also in antisunward flow, but close to the equatorward edge of the convection pattern, in the slower, diverging flow at the Harang discontinuity. A patch repetition time of some 10 to 30 min was estimated depending on the phase of the substorm.

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Drifting airglow patches in relation to tail reconnection

Cited by 63 publications

References 21 publications

GPS scintillation effects associated with polar cap patches and substorm auroral activity: direct comparison

GPS scintillation effects associated with polar cap patches and substorm auroral activity: direct comparison

EISCAT observations of plasma patches at sub-auroral cusp latitudes

Modulation of nightside polar patches by substorm activity

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