The ionospheric stopped, transparant sporadical E-layer in middle latitudes тема автореферата и диссертации по физике, 01.04.03 ВАК РФ

REPUBLIC OF GEORGIA TBILISI STATE UNIVERSITY

Licensed as manuscript

Nika Sharadze

HIE IONOSPHERIC STOPPED, TRANSPARANT SPORADICAL , E-LAYER IN MIDDLE LVTITUDES.

ptciality 01.02.03-radiophisics

ABSTRACT of the dissertation for receiving the scientific degree of candidate of physical and mathematical sciences

TbiIisi-1995

The work is made in the Tbilisi State University

Scientific supervisors: Doctoi'pf physical and mathematical sciences, ProfesorG.Kevanishvili

Official opponents: Doctor of physical and mathematical sciences. Professor A.G.Khantadze

Candidate of physical and mathematical sciences Z.I.Sikmashvili

The defence of the dissertation will take place "_*'

_ 1995 at_o'clock in the sitting of the

Tbilisi State University's Scientific-attestation council FM 01.02. N1-6(Chavchavadze avenue 3. Tbilisi State University. Tbilisi; 380028)

The dissertation can be found in the scientific library of Tbilisi State University. '

The abstract is distributed on " "_-1995

The secretary of die scientific council. Doctor of physical and mathematical sciences /T.Kereselidze/

-le-

Radiosounding of ionospfere at the height of E region (95- 120km) sometimes shovs thin (thickness l-3km) plasma layer with increased electronic concentration. Because of the irregular character of formation the given layer is called * sporadic"Actuality of investigation of sporadic E layer(Es) is caused not only by scientific but also purely by practical interest Es layer influences on conditions of spreading of radiowaves and determines the quality and reliability of radiocommunication. Ej layer is characterized by particular "sensitivity" at the active influence on atmos phere (magnetic storms, earthquake, eruption of voléanos, meteo.ic streams, atomic and industrial explosion*, launching of artificial satellites of the earth etc) and data of global investigations of the given layer are necessary to control surroundings investigate dynamics of ionospheric plasma interelation of various layers of the atmosphere magnitospheric and ionospheric relations-Mecharism of formation and qualities of Ej layer depend on the latitude.There are polar middle latitude and equatorial sporadic Ejlayers.On the ionograutms of radiosounding of ionospheres transparent (at the sametime reflections of E and F layers) and flayers are observed partially or com pletely screened the above lying layers.

Duration of continuous excitance of the transparent E¡layer (E) is much less than that of the screening Ej layer and mainly changes during an interval of I to 10 inmutes.''According to the international classification depending on the sort of ionogrammic trace at middle latitude: 4 different types (f,l,c,h) are distinguished Formation of the middle latitud': screening E layer is explained not by additional ionization of atmosphere but by redistribution of charged particles exciting, at the height of E region.

The main reason of this situation is that the experimental data is not sufficient due to insufficient information about shorttime Ejlayet ( expecially with interrupted ionospheric trace) given by the world piactice of ionospheric .radiosounding with the interval of 15 minutes. It is also necessary to mention the

frequancy and duration of the observation is mainly effected by the panmietres of the ionospheric station apparalures (capasity of the transmissor and scnseabily of the receiver). Due to all mentioned above, investigations .conducted op to now were mainly directed to the study of screening Ej-layer, and it is known veiy little about Ej layer. Unfortunately world net of ionospheric stations accumulated very little data on continuous non-stopped (with the interval of one minute) radiosounding, which is necessary for studying of the E% layer.

The purpose of the work: On the base of the frequent ( with the interval of I and 5 minutes) radiosounding of the ionosphere in middle latitude-moiphological study of the transparent, stopped, Ejlayer.

-study of the effect of atmospheric acoustic gravitation waves on the Ej-layer formation.

-modeling of the layer on ECM with the purpose of the investigations of informotion machanisms.

The main results: 1 .It is established dinamic origine of the transparent It is conducted its morpholocical investigation. On the base of it is established.

E^-layer is mainly observed in two levels: 95-110km and 115-140km.More frequently it is observed "Jaw" level 95-110 E-layer and it cover much wider frequency range l-8irJb than "higher" 115-i 40km E^-la^ .'.

During short period of its existance Ejlayer often becomes transparent and non-stopped, and according to international classification, corresponds to E-layer I or f type. Such transformation is more typical to "law" EJayer. -lis appearance and differentiations in in'ensivity and frequency range has quaziperiodical (T=3-30min) character. Most probable meanings of the fieriods are in the interval 5-20mir

The "life" period of the E^layei changes in the interval of 1-20 min. a 1 period of it existance is mainly l-6niin.

-The disappearance of the ionogram trace of the Es -layer does not occur 1 immediately and it starts to dissappeare in the highfrequency portion.

The vertical sizes of layer kvaziperiodical electronic inhotnogeneousness are changed in the intervals 30-70 m.

- In the period of E&- layer observation as a rule, the.moving ionospheric disturbances, caused by internal atmospheric acoustic-gravitation waves are

"observed in' F ionospheric environment, the disturbances will be exposed on ionograms as the distortions of ionogramic trace of F environment.

- In 24 hours variations of the possibility of PEjare observed two moximums in the evening and in the afternoon. PE»- in the season extertion, the maximum is obset d in winter (the main maximum) and in spring.

2. The mechanism of Es layer creation on the middle latitudes diffefs from so-called mechanism of "wind displacement" of-creation of screening Ey foyer.

Tl.e creation of Ej- layer is explained by resonance disperse of vadiowaves on kvaziperiodical (wave) heterogeneous structure of ionospheric. Spectra of frequency and vertical sizes of waves, - stipulating the kvaziperiodical heterogeneous ionospheric structure, dispersing the radio-waves,accordingly are in the intervals l-10Hz and 10-100m.

, 3. Kvaziperiodical heterogeneous ionospheric structure, dispersing the waves on altitudes in E-region may be created by infrasonic waves, which are generated in ' ' lthe period of great earthquakes, magnetic storms, the intrusion ol meteor flows -

(streams) into the upper atmosphere and by moving of atmospheric fronts. . The approbation of the work

The results, obtained in this dissertation were reported and discussed: on ;the First International Scientific conference, dedicated to Ponth. Greeks( Tbilisi, 1994) . On the ntemational scientific Conference on fundamental sciences ( Moscow 1995).

Основныв результаты диссертационной работы излокзны в следующих публикациях:

1. шарадае З.С., Шарадзо Н.Э. Прерывистый прозрачный опоради-чоокяй олой Ев ионосферы над Тбилиси. Труды Грако-Грузиноко-го университета им.Аристотеля, Тбилиси,1993, т.1, 235-237.

2. Шарадзе Н.З., Шарадзз З.С. К механизму образования ореднепш-ротного прозрачного опораднчоского слоя Ез ионосферы .

I Международная научная конференция, поовященная поптийоккм грекам. Тбилиси, 1994. 46-47.

3. Шарадзе Н.З. О механизма образования прозрачных прерывистых спорадических слэйв Е ионооферы на средних сиротах. Труда Греко-Грузинского университета им.Аристотеля, т.1,Тбилиси,

1994, 172-176.

4. Шарадзе Н.З. Резонансное отраженна радиоволн от периодачеоуя неоднородной структуры ионосферной плазмы и прозрачный, прерывистый спорадический олой Е на оредввх широтах. 'Груда

■ Грепо-Грузинокого универсиаета иы.Аг>чототеяя, Тбилиси,

1995. 1а- 1а