scholarly journals Interhemispheric asymmetry of the high-latitude ionospheric convection on 11-12 May 1999

2003 ◽  
Vol 108 (A5) ◽  
Author(s):  
Nozomu Nishitani ◽  
Vladimir O. Papitashvili ◽  
Tadahiko Ogawa ◽  
Natsuo Sato ◽  
Hisao Yamagishi ◽  
...  
Keyword(s):  
High Latitude ◽  
Interhemispheric Asymmetry ◽  
Ionospheric Convection

Interhemispheric asymmetry of the high-latitude ionospheric convection pattern

1994 ◽  
Vol 99 (A4) ◽  
pp. 6491 ◽  
Author(s):  
G. Lu ◽  
A. D. Richmond ◽  
B. A. Emery ◽  
P. H. Reiff ◽  
O. de la Beaujardière ◽  
...  
Keyword(s):  
High Latitude ◽  
Interhemispheric Asymmetry ◽  
Convection Pattern ◽  
Ionospheric Convection

scholarly journals Small-scale characteristics of extremely high latitude aurora

2009 ◽  
Vol 27 (9) ◽  
pp. 3335-3347 ◽  
Author(s):  
J. A. Cumnock ◽  
L. G. Blomberg ◽  
A. Kullen ◽  
T. Karlsson ◽  
Keyword(s):  
High Latitude ◽  
Large Scale ◽  
Small Scale ◽  
Strong Correlations ◽  
Polar Cap ◽  
Plasma Flows ◽  
Ionospheric Convection ◽  
Local Closure ◽  
Scale Characteristics

Abstract. We examine 14 cases of an interesting type of extremely high latitude aurora as identified in the precipitating particles measured by the DMSP F13 satellite. In particular we investigate structures within large-scale arcs for which the particle signatures are made up of a group of multiple distinct thin arcs. These cases are chosen without regard to IMF orientation and are part of a group of 87 events where DMSP F13 SSJ/4 measures emissions which occur near the noon-midnight meridian and are spatially separated from both the dawnside and duskside auroral ovals by wide regions with precipitating particles typical of the polar cap. For 73 of these events the high-latitude aurora consists of a continuous region of precipitating particles. We focus on the remaining 14 of these events where the particle signatures show multiple distinct thin arcs. These events occur during northward or weakly southward IMF conditions and follow a change in IMF By. Correlations are seen between the field-aligned currents and plasma flows associated with the arcs, implying local closure of the FACs. Strong correlations are seen only in the sunlit hemisphere. The convection associated with the multiple thin arcs is localized and has little influence on the large-scale convection. This also implies that the sunward flow along the arcs is unrelated to the overall ionospheric convection.

scholarly journals Comparison of the magnetic equivalent convection direction and ionospheric convection observed by the SuperDARN radars

2006 ◽  
Vol 24 (11) ◽  
pp. 2981-2990 ◽  
Author(s):  
L. V. Benkevitch ◽  
A. V. Koustov ◽  
J. Liang ◽  
J. F. Watermann
Keyword(s):  
Local Time ◽  
High Latitude ◽  
Early Morning ◽  
Auroral Oval ◽  
Magnetic Local Time ◽  
Ionospheric Convection ◽  
Morning Sector ◽  
Magnetometer Data ◽  
Different Seasons

Abstract. SuperDARN radar and high-latitude magnetometer observations are used to statistically investigate quality of the convection direction estimates from magnetometer data if assumption is made that the magnetic equivalent convection vector (MEC) corresponds to the convection direction. The statistics includes five full days, ~75 000 of joint individual measurements for different seasons. It is demonstrated that the best (worst) agreement between the MEC and ionospheric convection occurs for the sunlit, summer (dark, winter) ionosphere. Overall, the MEC direction is reasonable (deviates less than 45° from the SuperDARN direction) in at least ~55% of points and it is better for the latitudes of the auroral oval. In terms of the magnetic local time, the agreement is the best (worst) in the dusk (early morning) sector. Possible reasons for differences between the MEC and ionospheric convection directions are discussed.

scholarly journals Some aspects of modelling the high-latitude ionospheric convection from Cluster/Edi data

2013 ◽  
Vol 53 (1) ◽  
pp. 85-95 ◽  
Author(s):  
M. Förster ◽  
Y. I. Feldstein ◽  
L. I. Gromova ◽  
L. A. Dremukhina ◽  
A. E. Levitin ◽  
...  
Keyword(s):  
High Latitude ◽  
Ionospheric Convection

The Response of High-Latitude Ionospheric Convection During a Southward IMF Turning Event

2007 ◽  
Vol 50 (6) ◽  
pp. 1397-1406 ◽  
Author(s):  
Liang XU ◽  
Ji-Sheng XU ◽  
A. V. Koustov
Keyword(s):  
High Latitude ◽  
Ionospheric Convection

scholarly journals Different responses of northern and southern high latitude ionospheric convection to IMF rotations: a case study based on SuperDARN observations

2009 ◽  
Vol 27 (6) ◽  
pp. 2423-2438 ◽  
Author(s):  
D. Ambrosino ◽  
E. Amata ◽  
M. F. Marcucci ◽  
I. Coco ◽  
W. Bristow ◽  
...  
Keyword(s):  
Magnetic Field ◽  
High Latitude ◽  
Ionospheric Convection ◽  
Cell Pair ◽  
Cell Pattern ◽  
Southern High Latitude ◽  
Lobe Reconnection ◽  
Magnetospheric Field ◽  
The Imf

Abstract. We use SuperDARN data to study high-latitude ionospheric convection over a three hour period (starting at 22:00 UT on 2 January 2003), during which the Interplanetary Magnetic Field (IMF) flipped between two states, one with By>>|Bz| and one with Bz>0, both with negative Bx. We find, as expected from previous works, that day side ionospheric convection is controlled by the IMF in both hemispheres. For strongly northward IMF, we observed signatures of two reverse cells, both in the Northern Hemisphere (NH) and in the Southern Hemisphere (SH), due to lobe reconnection. On one occasion, we also observed in the NH two viscous cells at the sides of the reverse cell pair. For duskward IMF, we observed in the NH a large dusk clockwise cell, accompanied by a smaller dawn cell, and the signature of a corresponding pattern in the SH. On two occasions, a three cell pattern, composed of a large clockwise cell and two viscous cells, was observed in the NH. As regards the timings of the NH and SH convection reconfigurations, we find that the convection reconfiguration from a positive Bz dominated to a positive By dominated pattern occurred almost simultaneously (i.e. within a few minutes) in the two hemispheres. On the contrary, the reconfiguration from a By dominated to a northward IMF pattern started in the NH 8–13 min earlier than in the SH. We suggest that part of such a delay can be due to the following mechanism: as IMF Bx<0, the northward-tailward magnetosheath magnetic field reconnects with the magnetospheric field first tailward of the northern cusp and later on tailward of the southern cusp, due to the IMF draping around the magnetopause.

Electrodynamics surrounding polar cap auroral arcs

2021 ◽  
Author(s):  
Amalie Ø. Hovland ◽  
Kjellmar Oksavik ◽  
Jone P. Reistad ◽  
Marc R. Hairston
Keyword(s):  
High Latitude ◽  
Optical Data ◽  
Polar Cap ◽  
Ionospheric Convection ◽  
Ion Drift ◽  
Polar Latitude ◽  
Mesoscale Structure ◽  
Radar Network ◽  
Auroral Arcs

&lt;p&gt;This multi-instrument case study investigates the electrodynamics surrounding polar cap auroral arcs. A long-lasting auroral arc is observed in the high latitude dusk-sector at ~80&amp;#176; Apex latitude in the northern hemisphere. Ion drift measurements from the SSIES system on the DMSP spacecraft have been combined with multiple ground-based observations. Line of sight velocity data from three polar latitude high-frequency Super Dual Auroral Radar Network (SuperDARN) radars show mesoscale structure in the ionospheric convection in the region surrounding the arc. The convection electric field in this region is modelled using a Spherical Elementary Convection Systems (SECS) technique, using curl-free basis functions only. The result is a regional model of the ionospheric convection based on the fairly dense and distributed flow observations and the curl-free constraint. The model is compared to optical data of the auroral arc from two high latitude Redline Emission Geospace Observatory (REGO) all-sky imagers as well as UV images and particle measurements from the DMSP spacecraft to describe the local electrodynamics in the vicinity of the high latitude arc throughout the event.&lt;/p&gt;

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