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.

found that the shift of the auroral equatorward boundary was controlled by the IMP B z~component variations and did not depend on aubstorm occurrence. The data on the events examined in this report have been used to derive the regression equation relating the shift of the auroral equatorward bounda ry to the IMP B z-components дф'= 2.70° + 0.38 В s "r" - 0.87; 6 - 1.0, z where ДФ 1 is expressed in degrees, and B B in nT. By introducing into this expression the dependence of the Altitude of the equatorward boundary of the aurora on magnetic activity level (Starkov, 1 9 6 9 ), we obtain the expression for the latitude of the equatorward boundary* дф'« 74.7° - 0.9Q + 0. 3 8 B z - 5.1 cos15(t - 0.8), where t is the looal time in hours measured from midnight. It should be noted that the last expression disregards the Dst-variation contribution to the variations of the position of the daytime auroral zone. Peldstein et al.(1968) have shown that this effect is quite substantial. The noticeable equatorward shifts of the dayside cusp wi t h increasing Dst-varia tion were described by Meng (1983,1984). The results of model calculations of the Dst contribution to the equatorward shift of aurorae are presented by Siscoe (1979). SUMMARY AND CONCLUSIONS. The daytime auroral luminosities often exhibit various latitudinal differences in their spectral features, thereby indica ting different sources of the respective particle precipitations. The regicns of particle sources in the dayside magnetosphere, when mapped to the iono sphere within the field of v i e w of optical instruments at Svalbard and Heiss Island, ares ( 1 ) polar cap (plasma mantle/tail lobes); ( 2 ) cusp which is related to i) low latitude boundary layer and ii) entry layer; ( 3 ) region of closed magnetospheric field lines (i.e. dayside extension of plasma sheet boundary layer). The respective differences of the daytime auroral emissions in terms of position, form type, and speotral characteristics must be allowed for w h e n examining the optical data-inferred response of the cusp to the IMP and substorms. The experimental data presented permit the following conclusions concer ni n g the dayside cusp auroras. (1) The daytime precipitations of auroral particles have a complicated structure and consist of two regions. The first region ie a sufficiently hard precipitation w i t h I 5 5 7 . 7 7 I 6 3 0 . 0 * The r e 8 ion le characterised by re latively hard low-intensity precipitation and is associated with closed field lines (see P i g . 13). The second, broad (’v 3-4e ) region is characterized by softer precipitations with 1 5 5 7 . 7 < *630.0 b°r(*ers bard precipi tation йопе at its poleward boundary. Discrete auroral forms are observed in the equatorward zone of these soft precipitations. The discrete forms are characterized by their overall poleweird shift. Having been formed In the equatorward zone of the red luminosity region, the rayed arcs move by 1 - 2 * polewards and then disappear. They are replaced by new arcs whose motion direction is the same (see Pig.7,9 and in Vorobjev et a l . ,1975;1976). I4I