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.

4-.2.3. July 19, 1973; 10.00-18.00 ОТ I n that case there was no isolated oubstorm but some activity in advance. Magnetic stations (Pig.4b) in all local time sectors have seen disturbances, and magnetic activity came to an end at about 15.00 US at all stations.There are no indications for h i g h energy ion injections into the inner m a g n et o sphere - Dst remains positive and even increases (Pig.4a). Increased ab sorp tion has b e e n observed first (Fig.4a) b y the Alaska stations a nd Norilsk around magnetic midnight at 12.30 U T w i t h r ather sharp onsets. But the n it is confusing that stations in the before-noon-sector show n ea r l y no absorption (except the localized increase at Harsaarssuaq later), while stations in the n oo n sector (Angmagssalik, ICap Tobin) a nd in the a f ternoon seotor (Kevo, Ivalo, Sodahkyla) show precipitation. The afternoon absorption event again is most pronounced in Ivalo, but has also hi g h amplitudes in Ke vo a nd Sodan- kyla. Riomet e r absorption events i n the e v e n i n g - t o - a f t e m o o n sector and ifaeir connection wi t h the movement of IPDP events has b e e n studied b y Pikkarainen et al.(1986). But the explanation of these events seems to be an unsolved problem. 4.3. Example of injections i n the pre-midnight sector. July 19» 1973: 18.00-23.00 UT. This AA-event occurred i n connection w i t h a minor disturb ance after some quiet hours in the same day as that described in 4.2.3. M ag netic observatories close to midnight (Scandinavia, Dixon) recorded the onset of a substorm at or after 20.00 U T (Pig„5b) w i t h a duration u p to 23.30 UT. The corresponding AA-event (Pig,5c) is only seen near midnight i n Kevo,Ivalo and a little bit in Sodankyla, is ver y localized and did n e ither spread towards east n o r towards west. But about two houra later a sharp onset is s ee n in Кар Tobin and Harsaarssuaq w h i c h are then close to midnight. This Figure 5a. The same as Pig.1a Figure 4a. The same as Fig.1a on 19.7.1973. on 19.T . 1973. 97