Experimental results on the dynamics of the F region

Abstract

The first part of thi s pape r deal s with the response of the nighttime ionosphere to variations of th e earth's magneti c fi eld , es pecially to variations of its horizontal component. It is shown both theoreti· cally and experime ntally that the whole F region is set in moti on by suc h variations of the earth's mag· ne tic fi eld and that th ese motion s may be of an oscillatory or a non osc illatory c hara cte r. Amplitudes in real height of 75 a nd 200 km res pec tive ly are r~orte d. The second part of thi s pape r deal s with othe r kinds of ult.ra .low-frequ e nc y oscillatory mov e me nt of th e F regio n durin g magneti c all y qui e t winte r night s of whi c h som e last for at leas t 10 hr. A 3-station ne twork of id enti cal ionoso ndes allows inte rpre tati on of the m as trav eling wav es propagating mostl y southward and only occasion all y northward. Their phase ve lociti es cov e r th e ra nge 15 to 35 km/min a nd the res pective periods of dura· tion li e betw ee n 2.8 and 1.5 hr. Mi ss in g ionograms of the fi eld station s preve nted ph ase velocity cal c ulation s for a 0.7 hr wave. The amplitudes of all th e wave s co ve red th e ran ge be twee n 10 and 15 km. Traveling waves of lon ge r and s hort e r wav ele ngths may be poss ibl e but could not be de tecte d becau se of experime ntal reaso ns. It is be li e ved that th ese trave lin g waves re prese nt inte rnal gravit y wav es as sugges t.ed by Hin es [1960].

Vertical motions of the midlatitudeF2layer during magnetospheric substorms

“…authors have attributed this effect to electromagnetic drift [Martyn, 1953;Kamiyama, 1956;Maeda and Sato, 1959;Kohl, 1960;Becker et al, 1965;Riister, 1965Riister, , 1969Bullen, 1969;Evans, 1970;VanZandt et al, 1971;Park, 1971]. Unfortunately, no systematic study has yet been made of the response of the F2 layer to isolated magnetospheric substorms.…”

Doppler observations of associated ionospheric and magnetic fluctuations

“…It is found that from time to time, periods of high association2 occur, but most of the time there is very little or no association. Becker et al (1965) found that sequences of ionograms, taken a few minutes apart, exhibit vertical motions associated with magnetic declination changes. Also, F-region drifts were found by Kazmirovsky (1963) to be associated in a general way with dynamo current patterns deduced from magnetograms.…”

Heat conduction waves in the upper atmosphere

“…Traveling ionospheric disturbances (TID) can be observed in the F• layer even during magnetically quiet days [Heisler, 1963;Becker et al, 1965]. They propagate with horizontal speeds of the order of 100 m/see and apparently move downward with velocities of the order 10 m/sec.…”