Электродинамические процессы в высоких широтах: материалы междунарордного симпозиума «Полярные геомагнитные явления», 25-31 мая 1986 г., Суздаль, СССР / Междунар. геодез. и геофиз. союз, Междунар. ассоц. геомагнетизма и аэрономии ; Акад. наук СССР, Кол. фил. им. С. М. Кирова, Поляр. геофиз. ин-т ; [редкол.: О. М. Распопов (отв. ред.). и др.]. - Апатиты : Кольский филиал АН СССР, 1988.

Russell et al.(1971) first reported evidence of cusp motion, in response to changes in the IMP B a . A close connection b etween southward (northward) turnings of B_ and equatorial (poleward) movement of the auroral zone has b e e n demonstrated (cf.Akasofu et al.,1973; Pike et al.,1974; V orobjev et al., 1976; Makita et al.,1983-). Studies based on ground-based photometers (Sand- holt et al.,1983, 1985) an d low-orbiting polar satellites (Meng,1982; 1983) also indicate that the position of the polar cusp depends: closely o n th« orientation of the IMF, Kamide et al.(197&) demonstrated that the latitude of the cusp depends not oxU.y on I M F B a but elsb o n substorm activity as reflected b y the A E index. Thus, the existing information indicates that both IMF orientation and substorm activi t y control the location of the magnetospherio cusp. H o w ever, a n extreme vi e w holds that substorm activity alone controls the loca tion of the polar cusp (Eather et al.,1979; B a t h e r , 1985). 2. PRESEHTATION OF DA T A SET HO 1. In this section we focus o n the m i d day and evening-midnight sectors of the auroral oval an d their responses to IMP variations, based on simultaneous optical measurements from Svalbaz'd (Norway) and Alaska. The nighteide aurora is used as a sensor of the state of the magnetosphere, including subatorm activity. The dayside auroral emissions were recorded b y a set of phototubes placed in front of a r o tating mirror, providing photometer scans along the geomagnetic meridian. B y this technique the dayside аигогаз can be observed wi t h i n the range ~ 70-80° geomagnetic latitude at midwinter (e.g.Sandholt et al.,1985). Local magnetic n o o n an d solar n o o n at the r e cording site occurs at ~ 0830 a n d ~ 11 UT, respectively. Geomagnetic disturbances we r e recorded by standard m agnetometers at four stations on Svalbard, covering the range 71.1-75.4° geom.lat. O n the nightside, the Alaska c h a i n of magnetometer stations was used (Akasofu et al.,1983). A set of mer i d i a n scanning photometers was also operated at Poker Flat, Alaska (65° geom.lat.). This site Is displaoed 10 hours in looel time re l a tive to Svalbard. The observations ma y be separated i n three categories: i) large-scale d y n a m i c s ; the term large-scale refers i?o both time duration (tens of minutes) and spatial dimension (the enture belt of l u m i n osity a ssociated w i t h the polar ouep)$ ii) small-scale d y n a m i c s » the term small-scale dynamics refers to i n dividual luminosity structures w i t h limited spatial extent a n d w i t h l i f e - . times of the order of minutes. C ertain observed features i n the dayside aurora w i t h such scales m a y be the signature of flux transfer events (FTEs) wh i c h are observed Д>у satellites ne a r the dayside magnetopause (e.g.Russell and Elphic,1979; R i jnbe^k et al,,1984; Lee a n d Fu,1985). A c c ording to the present standard model, FTEa are characterized b y a rather ahort-lived and local magnetic connection across the dayside magnetopause, which is initia ted b y a transient reconnection b etween m a g n e t osheath an d magnetospheric field lines. D u r i n g such events m agnetosheat h plasma elements are expected to be injected along the interconnected flux tube (cf.Cowley,1984) w i t h the possible effect of producing certain luminosity signatures in the upper atmosphere of the cusp region; iii) optical emissions i n re l a t i o n to convection currents i n tha polar cusp and cap i a n o a p h e r e s : A mer i d i a n chain of magnetosphere stations rota- 118