IMF <i>B</i><sub><i>y</i></sub> effects in the plasma flow at the polar cap boundary

Abstract

Abstract. We used the dataset obtained from the EISCAT Svalbard Radar during [2000][2001][2002][2003][2004][2005][2006][2007][2008] to study statistically the ionospheric convection in a vicinity of the polar cap boundary as related to IMF B y conditions separately for northward and southward IMF. The effect of IMF B y is manifested in the intensity and direction of the azimuthal component of ionospheric flow. The most significant effect is observed on the day and night sides whereas on dawn and dusk the effect is essentially less prominent. However, there is an asymmetry with respect to the noon-midnight meridian. On the day side the intensity of B y -related azimuthal flow is maximal exactly at noon, whereas on the night side the maximum is shifted toward the post-midnight hours (∼03:00 MLT). On the dusk side the relative reduction of the azimuthal flow is much larger than that on the dawn side. Overall, the magnetospheric response to IMF B y seems to be stronger in the 00:00-12:00 MLT sector compared to the 12:00-24:00 MLTs. Quantitative characteristics of the IMF B y effect are presented and partly explained by the magnetospheric electric fields generated due to the solar wind and also by the position of open-closed boundary for different IMF orientation.

Effects of the interplanetary magnetic field on the location of the open‐closed field line boundary

“…One of the most important impact factors is the Y component of IMF. As the results of some previous studies, B Y can lead to an asymmetry of the two‐cell plasma convection pattern at the high‐latitude ionosphere [e.g., Heelis , ; Reiff and Burch , ; Heppner and Maynard , ], thereby the asymmetry of the OCB [e.g., Lee et al , ; Lukianova and Kozlovsky , ].…”

“…When the IMF has a positive(duskward) component in addition to the southward B Z , the reconnection sites at the dayside magnetopause move from the equator to higher latitude of Northern Hemisphere at duskside and Southern Hemisphere at dawnside [ Park et al , ]. This causes a dawnward plasma flow in polar cap, and the duskside cell becomes more dominant than the dawnside [e.g., Cowley et al , ; Lukianova and Kozlovsky , ], as shown in Figure b. The dawnward flow brings more open flux to dawnside; thus, the dawnside OCB has a lower latitude than duskside OCB at the Northern Hemisphere.…”

Determination of Polar Cap Boundary for the Substorm Event of 8 March 2008

“…Since the upstream solar wind conditions have a major influence on the reconnection of magnetopause/magnetotail, its variations may lead to the dynamics of PCB. Especially, the Y component of IMF can cause an asymmetry of the two-cell plasma convection pattern at the high-latitude ionosphere (e.g., [3,4]), thereby the dawn-dusk asymmetry of cutoff latitudes for protons and electrons [5], and polar cap boundary (e.g., [6,7]). In many studies, the polar cap boundary and area were used as a diagnostic of magnetospheric activities specifically during a substorm cycle (e.g., [8][9][10][11][12][13]).…”

A quantitative deconstruction of the morphology of high‐latitude ionospheric convection

“…Recently, studies have increasingly focused on asymmetries in the coupled magnetosphere‐ionosphere system [e.g., Sandholt and Farrugia , 2007; Laundal et al , 2010; Shi et al , 2010; Grocott et al , 2010; Lukianova and Kozlovsky , 2011]. Such asymmetries are intrinsically linked to the mechanisms that drive the dynamics of the system and in order to fully understand these mechanisms the asymmetries they introduce must be fully understood.…”