Ионосферные явления - 81 : материалы наблюдений Полярного геофизического института по проекту "Международные исследования магнитосферы" за 1981 г. : (оперативно-информационный материал) / Акад. наук СССР, Кол. фил. им. С. М. Кирова, Поляр. геофиз. ин-т ; [редкол.: О. И. Шумилов (отв. ред.), Л. В. Ковалевская]. - Апатиты, 1989.

4 IONOSPHERIC PHEN0MENA-81 USSH A ca demy of Sciences E d it o r O.I.Shumilov The volume contains th£ results of ionospheric o bservations carried out i n the Polar Geophysical Institute and continues the series of publications started in 1970 /1/. Since 1977 the data are pu blished in two volumes: "Auroral Phenomena" /2/ w i t h the results of geomagnetic auroral a nd b al loon observations and "Ionospheric Phenomena" /3/ w i t h the data of vertical sounding, a b s orption measurements, and radar observations. In Murma n s k ionospheric sounding is carried out b y me a n s of the AIS i onosond w i t h fr equency range 1-20 Ши, sweep time 30 s, height range 1500 ton, I onograms are taken every 15 min. I nformation on ionospheric sounding is presented in the form of f-plots standard d esignation /6,7/ additi o n al l y explained i n the R u s s ia n text. Ab s o rp t i on me asurements at st.Loparskaya were carried out by means of a standard riome t er w i t h frequency of 32 MHz, band width of 90 KHz, time integration 30 s, the antenna m a i n lobe 50x60° directed towards the Pole Star. The base line is derived fro m quiet days records, the m on t h ly ab s o rp t i on v a ri a t io n is g i v e n on the graph, days w i t h complete absence of ab s o rption are excluded. Radioaurora observations at st.Essoila were performed by means of the r a da r on f-88 MHz w i t h the ba nd w i d t h of 270 KHz, power in pulse 60 KW, range of 1250 km, the period of antenna rotation 40-90 s. The time of radioaurora occurence is gi v e n in Tables. The geographical and corrected geomagnetic coordinates of stations a ccording to calculations /5/ are the following: M u r m an s k У =69.0°, Л =33.0°, Фс=64.5°, Лс= 1 15.2°, L =5.5; Loparskaya У =68.3°, Я =33.1? ф£ =64.0°, Лс= 1 14.8°, L =5.2; Essoila У =61.8°, ^ =33.3°, =57.5°, Лс=111°. Universal time is use d everywhere. The behaviour of the ionosphere significantly depends on the presence of magnetospheric disturbances. Their distr ib u t io n over the year is examined in /4/. In m o s tl y compact form this d istribution is presented in the Calendar, F i g . 1. Estimations of activity is gi v e n according to ionospheric, geomagnetic, and auroral observations. The g ro w t h of activity is denoted by black spots. It is evident that the three types of activity estimations agree rather well; though the acti v i ty level turns to be slightly different disturbances are registered more oft e n from ionospheric indices tha n from the two other forms. Diurnal variations of activity w i t h the daytime m i n i m u m (the middle of each line) as well as seasonal variations w h e n the activity level is hi gher in the first half of the ye a r are seen. The days in the Calen d a r are arranged according to the Bartel's rota t io n n u m be r 2015-2029. The plot in P i g . 2 also presents evaluation of activity since it contains rn daily m e a n values. The IMP signs (positive fr o m the Sun) are also given. Changes of illumination of the ionosphere determine electron density in D, E, PI lower ionospheric layers gr adually changing density reaches its m a xi m u m iiear n o o n (10 UT). These layers disappear during quiet w in t e r nights. Disturbances create additional ionization r e g istered as appearence of sporadic E - layer as well as increase of absorption.