4dv. Space Res. Vol.4, No.4, pp.163—166, 1984 0273—1177/85 $0.00 + .50 Printed in Great Britain. All rights reserved. Copyright ©COSPAR IONOSPHERIC AND STRATOSPHERIC EFFECTS OF A PROTON FLARE DURING UNUSUAL SOLAR ACTIVITY — 22 NOVEMBER 1977 P. Velinov,* G. Nestorov,* Ch. Spasov,* Ts. Dachev** and Y. Tasev*** * Geophysical Institute at the Bulgarian Academy of Sciences, acad. G. Bonchev Street, BI. 3, Sofia 1113, Bulgaria * * Central Laboratory for Space Research at the Bulgarian Academy of Sciences, Russki Street No 1, Sofia 1000, Bulgaria ***H~lil Suppression Administration, Sofia, Bulgaria ABSTRACT The effect of the proton flare of 22 November 1977 on the various levels in the middle atmosphere and the bottom—side ionosphere is studied in order to compare synchronous phenomena in the middle atmosphere with phenomena inupper regions and to investigate the response of middle atmosphere to the penetra- tion of high energy solar particles and radiation, INTRODUCTION Proton flare of 22 November 1977 was the largest corpuscalar event since the famous phenomena of 4 May and 12 and 15 November 1960, subject to particular investigation in /1,2,3/. The event of 22 Nov. 1977 developed against theback— ground of a relatively calm ionospheric and magnetospheric situation near the phase of solar activity. Thus this was the first occurrence of excessive ac- tivity of processes in the solar—terrestrial environment after ti~ solar mini.itun in 1976. The examined flare was accompanied by significant additional cosmic ray(CR) flux associated with the McMath Plage region 15031, recorded at many stations and by satellites and stratospheric balloons/4/. MIDDLE ATMOSPHERIC IONIZATION FROM X-RAY AND SOLAR COSMIC RAY PENETRATION The event of 22 Nov. had many effects on the ionosphere and middle atmosphere, one of them being the anomalous increase in the radiowave absorption L,record— ed at the ionospheric laboratory of Sofia at a frequency of 164 kHz along the Allouis(France) — Sofia path (1720 kin). Ll64 thus measured reveals the ioni- zing situation in the region of 50—80 km. Figure 1 illustrates the intensity of the electromagnetic field E,j~V/xnthroughout the period of the event(solid ~ v/us to II 12 UT 154 kHz/l72fJkm F IA .OLAP COSMIC RAYS 22. 11.1977 So SI D 0 Fig. 1. Electromagnetic field intensity variations during the proton flare