V.D. Tereshchenko, V.A. Tereshchenko (Polar Geophysical Institute, Murmansk, Russia)

The coherent evolution of gradient drift instability in the ionospheric F-region is considered when the effects of Coulomb collisions and enhanced electric field are taken into account. In definite geophysical conditions the amplitude of relative perturbations of electron density is calculated. The basic set of equations that we use for analysis is the gas dynamics equations. The perturbations of density can be written as a superposition of crossed plane waves running in a direction orthogonal to gradient of density and geomagnetic field. The saturation of gradient drift instability at the expense of nonlinear generation of even harmonics along the gradient of electron density corresponds to a soft mode of turbulence occurrence. The effect of an external electric field shear is considered. It is shown, that its influence on stabilization of instability under existing conditions is not great.
 
 
 
 

A MEASURING FACILITY OF POLAR GEOPHYSICAL INSTITUTE FOR IONOSPHERIC STUDIES BY PARTIAL RADIOREFLECTIONS METHOD

V.D. Tereshchenko, E.B. Vasiljev, O.F. Ogloblina, T.N. Semjashkina, M.V. Yakimov
(Polar Geophysical Institute, Murmansk, Russia)

During a few years, Polar Geophysical Institute researches the lower ionosphere with the partial reflection technique. The measuring station is located on the Kola peninsula near Tumanny (69.0° N, 36.7° E). The characteristics and the block diagram of the station are considered and the examples of the partial reflection of ordinary and extraordinary wave modes are introduced. The wave modes are transmitted as alternating pulses with the antenna array which consists of 32 antenna elements with a rotating field polarization. The experimental data contain the  information about processes in the ionosphere, a nature of the irregularities, and the data also give a possibility to compute the electron density and the electron collision frequency. The measuring station includes 3 spaced antennas on the ground level with the baselines 164 m for transverse drift velocity estimates.  Some figures illustrate the measured parameters of the lower ionosphere. The antenna array is being reconstructed for 64 antenna elements utilization.
 
 
 
 

NUMERICAL MODELING OF THE LONGITUDINAL VARIATIONS IN THE NEAR-EARTH PLASMA

O.V.Martynenko ^1,2, A.A.Namgaladze ^1,2, A.N.Namgaladze ² and V.A.Shlykov ^3
1 Murmansk State Technical University, Murmansk
² Polar Geophysical Institute, Murmansk
³ Murmansk Polytechnical Lyceum, Murmansk

We have obtained the first numerical results of modeling of the longitudinal variations in the ionosphere and plasmasphere of the Earth for the March equinox of 1974 (low solar activity) using the global upper atmosphere model (Namgaladze et al., 1998) and compared these results with the data of the empirical International Reference Ionospheric model IRI-95. The results have been plotted and analyzed in the geomagnetic coordinate system for the 12 and 24 MLT conditions. We tried to find the relations between the longitudinal variations of the electron concentration in the geomagnetically conjugate F2-layers, at the base of the protonosphere and at the tops of the geomagnetic field lines. These relations are very complicated and differ for midday and midnight conditions due to the different responses of the ionosphere and plasmasphere to the longitudinal variations of the thermospheric winds and neutral gas composition. All of them are caused mainly by the offset between the geomagnetic and geographic axes.
This work was supported by the Grant No.98-05-64145 of Russian Foundation for Basic Research.

Namgaladze A.A., O.V.Martynenko, M.A.Volkov, A.N.Namgaladze, R.Yu.Yurik. High-latitude version of the global numerical model of the Earth-s upper atmosphere. Proceedings of the MSTU., v.1, No.2, p.23-84, 1998.
 
 
 
 

GLOBAL IONOSPHERE-PROTONOSPHERE STORM MODELING

A.A. Namgaladze ^1,2, R.Yu. Yurik ^1,2
1 Murmansk State Technical University, Murmansk, Russia
² Polar Geophysical Institute, Murmansk, Russia

To test various hypotheses concerning the relations between the plasmapause, main ionospheric trough and light ion trough dynamics, we performed the numerical simulation case studies for the magnetic storms of 24-27 January 1974 (moderate storm, solstice, low solar activity) and 3 April 1979 (strong storm, equinox, high solar activity) to obtain the global patterns of the protonospheric and ionospheric effects of these different magnetic storms.
The global upper atmosphere model (UAM) by Namgaladze et al. (1998) has been used in the investigation with the resolution of the numerical integration of the modeling equations 2 degree in latitude for all ionospheric and protonospheric parameters. This model describes the Earth's mesosphere, thermosphere, ionosphere, plasmasphere, and the inner part of the magnetosphere confined by the closed geomagnetic field lines as a single system including its electrodynamics. The cross-polar cap electric potential was estimated from the hourly AE index according to Weimer et al. (1990) and served as the main model input parameter.
The results of the numerical simulation show the coupled storm dynamics of the ionospheric F2-layer troughs, light ion troughs and plasmapause under different geophysical conditions for different MLT sectors. Much more prominent plasmapause dynamics has been noticed for the April 1979 magnetic storm in comparison of that of January 1974.The contributions of the themospheric winds and gas composition storm changes as well as those of electric fields and geomagnetic field tube filling and depletion processes are considered. This work was supported by the Grant No.98-05-64145 of Russian Foundation for Basic Research.

References

Namgaladze A.A., O.V.Martynenko, M.A.Volkov, A.N.Namgaladze, R.Yu.Yurik. High-latitude version of the global numerical model of the Earth-s upper atmosphere. Proceedings of the MSTU., v.1, No.2, p.23-84, 1998.

Weimer, D.R., N.C. Maynard, W.J. Burke, and C.Liebrecht, Polar cap potentials and the auroral electrojet indices, Planet. Space Sci., v. 38, p.1207--1222, 1990.
 
 
 
 

PLASMA BLOB CONVECTION IN THE HIGH LATITUDE IONOSPHERE

A.E. Stepanov ¹, V.L. Khalipov ¹, V.V. Afonin ², E.K. Zikrach ^1
1 Institute of Cosmophysical Research and Aeronomy, Yakutsk
² Space Research Institute, Moscow

The high latitude plasma blob measurements by Yakutian meridional chain of ionosoundes and the Cosmos - 900 satellite are analyzed. Model calculations carried out with the stationary model of the electric field (IZMEM) showed that blobs are formed in the day side cusp region during sharp changes of the interplanetary magnetic field (IMF) parameters. Using large statistics of measurements, time periods were found, when after abrupt change of IMF and blob formation the convection pattern in the polar ionosphere was stationary. In these conditions the calculated time of blob displacement from the cusp to the region of registration well agrees with observed transport time.
The data referred to the registration of plasma blob structure with extremely enhanced electron density observed during many hours on the polar edge of the main ionospheric trough on November 11, 1981 are analyzed in details.
 
 
 
 

VERTICAL WINDS IN THE AURORAL ZONE IN QUIET AND DISTURBED CONDITIONS

S.V. Leontyev, N.N. Bogdanov (Polar Geophysical Institute, Apatity, Russia)

Vertical winds behavior within auroral zone was investigated. It was demonstrated that under disturbed conditions, vertical winds undergo considerable (up to 100 m/s) variations both at night and from night to night. In quiet conditions, if there are no any aurora, the vertical wind velocity remains constant within the range 5 m/s, during the entire observation period, which allows us to use it as a zero reference point, when neutral winds are measured. Large variations of wind velocity are connected to aurora and spatial size of these disturbances is more then 200 km. While during the 1998-1999 season, vertical wind is predominantly upward under disturbed conditions. Some sources of wind disturbances are discussed.
 
 
 
 

A REVIEW OF ALL POWERFUL VLF DISTURBANCES INITIATED BY THE SUPPER RELATIVISIC ELECTRON PRECIPITATION WHILE 1974-1992 YEARS

M.I. Beloglazov (Polar Geophysical Institute, Apatity, Russia)
G.F. Remenets (Institute of Radiophysics, State University of St.-Peterburg, Russia)
V.P. Nemirov (Physics Department, State University of St.-Peterburg, Russia)
 
 

A phenomenon description is given and a quantitative analysis is fulfilled for all 14-16 powerful VLF disturbances of the polar radiotrace Aldra-Apatity (885 km) registrated in PGI AS USSR during the interval 1974-1992 years. The so far unpublished events are the following: 16.04.84 (17.30-18.10-19.40 UT), 27.03.88 (09.30-11.00-19.00 UT), 01.04.88 (07.40-08.00-09.00 UT), 01.04.88 (10.50-12.00-13.30 UT), 02.04.88 (18.50-20.15-21.30 UT), 03.04.91 (12.05-13.00-14.30 UT), 03.04.91 (15.00-16.12-18.50 UT), 21.01.92 (22.00-22.50-24.00 UT), 22.01.92 (06.15-07.40-10.00 UT).
A disturbance is called powerful if an amplitude of one or the amplitudes of two or three radiosignals (the signals of the OMEGA radionavigation system were used with the frequencies 10.2, 12.1, 13.6 kHz) becomes or become equal to the apparatus zero in the conditions of linear amplification with 20 Hz effective frequency range. Such realization is possible only in conditions when the atmosphere along the radiotrace is intensively ionized at the height interval 20-40 km. The cause of anomalous ionization are the supper relativistic electron precipitations [1]. The quantitative analysis in our case is the solving of the inverse VLF problem in the set of the unmonotonous electron concentration profiles which are the rough approximations to two layers of ionized atmosphere: the top layer is a normal ionosphere and the bottom layer is due to the anomalous ionization.
The estimation results of the VLF inverse problem solutions are represented in a Table for some powerful VLF disturbances at the time of their maximum amplitude and phase variation for all three signals. In this Table Z₁ and b are the parameters of an effective unmonotonous electron concentration profile which have been found by the minimization of a functional with the differences between the experimental and theoretical values of amplitude and phase magnitudes [2]. Z₁ - is a bottom level of a layer with homogeneous electric conductivity at the range Z₀ - Z₁ km and with Z₀=62 km. b - is a height increment of the bottom part of the effective profile. A parameter h at the same Table is an effective height of a waveguide formed by the Earth and ionized middle atmosphere. The calculation of the parameter h is not neccesary for the solving of the inverse problem but it is metodologically useful because, as it is shown in the scientific literature, this effective height is located inside the so called essential region of electric conductivity layer relative to the radiowave reflection.

At all powerful VLF disturbances the b is negative and the effective height is low, so an existance of abnormal powerful ionization of the atmosphere at the heights 20-40 km is proved.
Acknowledgements: This work was supported by the grant N 99-05-64979  from the Russian Foundation for Basic Researches.

[1] Remenets G. F., Beloglazov M. I. Ground VLF Monitoring of the Ultrarelativistic Electron Precipitations // Problems of Geospace 2. Proceedings of the 2nd Intrenational Workshop held at St.Petersburg, Russia, June 29- July 3. - Austria, Vienna: Austrian Academy of Sci. Press, 1999. P. 275-281.
[2] Remenets G.F. Unique ground VLF monitoring of relativistic electron precipitations // Problems of Geospace. - Austria, Vienna: Austrian Academy of Sci. Press, 1997. P. 273-278.
 
 
 
 

OBSERVATIONS ON PARTIAL REFLECTION RADAR DURING NOCTILUCENT CLOUD APPEARANCE

V.C. Roldugin, V.D. Tereshchenko, Ye.B. Vasiljev (Polar Geophysical Institute, Apatity, Russia)

Accordingly to visual and photographic observations from Umba town, at 7 August 1999 a noctilucent cloud have appeared over the partial reflection radar (PRR) 2.7 MHz in Tumanny (69.0 N, 36.7 E) between 2135 and 2150 UT. Its form may be classified as waves of small intensity. In this time interval strong reflection was observed at heights from 70 to 87 km both in usual wave component and in unusual one. The increase of reflection intensity was nearly uniform along this altitude interval. The electron density profiles, determined on PRR data, revealed 2-5 times decrease of electron concentration at this time on 70 - 85 km. The wind pattern in the mesopause showed turbulent motion with relatively small velocities and predominant westerly direction.
The Esrange MST radar near Kiruna displayed several intensive PMSEs this day up to 1900 UT. PRR revealed also usual PMSE with the presence of maximum in altitude profile, but in other periods.
 
 
 
 

МОДЕЛИРОВАНИЕ МОДИФИКАЦИИ НОЧНОЙ ВЫСОКОШИРОТНОЙ F-ОБЛАСТИ КОРОТКИМИ ВОЛНАМИ РАЗЛИЧНОЙ ЧАСТОТЫ

В.С.Мингалев, Г.И.Мингалева, И.В.Мингалев (Полярный геофизический институт,Апатиты)

Метод активного воздействия успешно применяется для изучения физических свойств ионосферной плазмы. Одним из эффективных активных воздействий на ионосферу является облучение ее мощными радиоволнами КВ-диапазона, излучаемыми наземным нагревным стендом. Однако, в экспериментах по искусственной модификации высокоширотной ионосферы большинство достижений относятся к D- и E-слоям. Успехи в модификации высокоширотного F-слоя весьма скромны. Как показали ранее проведенные расчеты [1-3] главной причиной этого является то, что плазма высокоширотного F-слоя не остается неподвижной относительно нагревного стенда, а может перемещаться над ним с довольно большой скоростью под действием электрического поля конвекции. Поэтому те изменения, которые происходят в плазме под действием мощных КВ, следует наблюдать не над самим нагревным стендом, а в примыкающей к нему зоне, вытянутой в направлении конвекции ионосферной плазмы.
Для планирования режимов работы нагревного стенда и размещения наземных диагностических средств, которые бы позволили зафиксировать изменения в высокоширотном F-слое, обусловленные действием радиоизлучения, может быть применен метод математического моделирования. Ранее [3] мы исследовали влияние энергии облучающей волны на ионосферный эффект норвежского нагревного стенда ( Тромсе ).
Настоящая работа является продолжением [3], ее целью является исследование влияния частоты греющей волны на те изменения в высокоширотном слое F, которые должны вызываться этой волной. В работе приводятся полученные с использованием математической модели [1] результаты расчетов, выполненные для норвежского нагревного стенда при его работе в ночных условиях.

[1] Mingaleva G.I.,Mingalev V.S. Ann. Geophys., v.15, pp.1291-1300, 1997.
[2] Mingaleva G.I.,Mingalev V.S. In:"Physics of Auroral Phenomena".Proс. XIX Annual Seminar, Apatity, pp.87-88, 1996.
[3] Mingalev V.S.,Mingaleva G.I. In:"Physics of Auroral Phenomena". Proс. XXII Annual Seminar, Apatity, pp.61-64, 1999.
 
 
 
 

IONIZATION CREATED BY SOLAR PROTONS FROM CALCULATIONS AND DIRECT EISCAT DATA

E.V. Vashenyuk, A.B. Pashin (Polar Geophysical Institute, Apatity, Russia)
I.V. Loseva (Kola Branch of Petrozavodsk State University, Apatity, Russia)

An effect of solar protons on the electron density in the lower ionosphere has been calculated. The solar proton flux, energy spectrum as well as rates of ionization and recombination were taken into account. The calculated altitude profiles of electron density were then compared with direct measurements by the incoherent radar EISCAT during three powerful solar proton events. 24.10.1989, 15.11.1989 and 21.05.1990. Preliminary results of this study are reported.
 
 
 
 

IONOSPHERIC EFFECTS CAUSED BY ENERGETIC SOLAR PROTONS ON EISCAT DATA

Kh. Fadel (Swedish Institute of Space Physics, Kiruna, Sweden)
E.V. Vashenyuk, A.B. Pashin (Polar Geophysical Institute, Apatity, Russia)
I.V. Loseva (Kola Branch of Petrozavodsk State University, Apatity, Russia)

Observations by the EISCAT incoherent radar during powerful solar proton events of October 24, November 15, 1989 and May 21, 1990 have been analyzed. The data of neutron monitor in Apatity and GOES spacecraft were used to study a relationship between solar proton flux at different energy domains and corresponding ionization changes. The altitude profiles of electron density in the altitude range of 70-150 km have been obtained. The detailed correspondence between variations of the solar proton flux and electron density at fixed altitudes has been observed. It was noted also the daily variations of electron density caused by solar luminosity changes.
 
 
 
 

МОДЕЛИРОВАНИЕ ПРОСТРАНСТВЕННОЙ СТРУКТУРЫ ВЫСОКОШИРОТНОЙ ИОНОСФЕРЫ НА УРОВНЯХ D-, E- и F-ОБЛАСТЕЙ

Г.И. Мингалева, А.С. Кириллов, Г.А. Аладьев, В.С. Мингалев
(Полярный геофизический институт, Апатиты)

В работе описывается новый вариант пространственно 3-мерной математической модели высокоширотной ионосферы, в котором высотная область расчетов охватывает не только F- и E-слои, но также и D-слой ионосферы.В этом варианте были объединены две ранее разработанные модели: 1) модель конвектирующего высокоширотного F-слоя; 2) модель высокоширотной средней и верхней атмосферы.
Первая модель позволяла рассчитывать 3-мерные стационарные распределения электронной концентрации, электронной и ионной температур, а также скорости положительных ионов на уровне F-слоя в высокоширотной области, охватывающей как полярные так и субавроральные широты. Подробное описание этой модели содержится в [1].
Вторая модель позволяла рассчитывать химический состав атмосферы на уровнях слоев D и E. Она основывалась на численном решении системы нестационарных 1-мерных уравнений неразрывности для 32 сортов частиц, среди которых можно выделить семейства положительных и отрицательных ионов, а также основных, малых и возбужденных нейтральных составляющих атмосферы. В модели учитывались процессы ионизации и диссоциации основных и малых нейтральных составляющих атмосферы солнечным излучением и авроральными электронами, а также 132 химические реакции между рассматриваемыми компонентами атмосферы. Эта модель является несколько усовершенствованным вариантом модели, использовавшейся в работе [2].
Вариант математической модели, объединяющий две указанные выше модели, позволяет в пределах расстояний от земной поверхности 70-700 км в 3-мерной области, охватывающей как полярные так и субавроральные широты, рассчитывать электронную концентрацию, а кроме того, в нижней части ( 70-130 км ) - концентрации различных учитываемых моделью заряженных и нейтральных частиц, а в верхней части ( 130-700 км ) - электронную и ионную температуры, а также скорость положительных ионов.
Апробация нового варианта математической модели показала, что он воспроизводит основные крупномасштабные неоднородные образования в полярной и субавроральной ионосфере, известные по данным наблюдений.

[1] Мингалева Г.И., Мингалев В.С. В сб.: Моделирование процессов в верхней полярной атмосфере, с. 251-265, Мурманск, 1998.
[2] Mingalev V.S., Orlova M.I., Kirillov A.S., Aladjev G.A., Mingaleva G.I. In:"Physics of Auroral Phenomena".Proc.XXI Annual Seminar, Apatity, pp.83-86,1998.
 
 
 
 

DISTURBANCES OF AURORAL ELECTROJETS INDUCED BY IONOSPHERE HF HEATING

A.L. Kotikov (St. Petersburg State University, St. Petersburg, Russia)
A.B. Pashin, E.Yu. Grazhdantseva (Polar Geophysical Institute, Apatity, Russia)

Disturbances of the auroral electrojets produced by HF ionosphere heating is studied. Intensity and location of the ionosphere currents are deduced from data of IMAGE magnetometer chain with 10 second time resolution. At midnight sector without differences to heating regime (modulated or long pulse action) the stabilisation of the equatorward border of the westward electrojet at latitude of the heater is observed. For modulated heating each duty cycle of the transmitter is accompanied by enhancement of the ionospheric currents and poleward displacement of those. In the evening sector heating in the region of the eastward electrojet leads to increase of its current density with concurrent decrease of intensity of the westward electrojet occupying the region to the pole from the eastward one. Close temporal and spatial relationship of substorm intensifications to the region of ionosphere modification makes a suggestion on influence of ionosphere parameters (conductivity, polarisation electric fields) on the development of substorm. This results prove an active role of E-region of the ionosphere on the generation of small-scale structure of ionospheric and field-aligned currents and argue the ionospheric origin of multi-layer current structure observed during substorm. Close correspondence of auroral structure and ionospheric current dynamics during ionosphere modification experiments is also marked.
Numerical modelling of the disturbances is presented. The modeling includes calculations of disturbed electric field potential in horizontal inhomogeneous ionosphere, ionospheric and field-aligned currents, and magnetic disturbances on the ground. Two cases of voltage and current generator are considered. In the case of voltage generator local modification of ionospheric conductivity is able to produce only small-scale magnetic field disturbances. The case of the current generator seems to be more interesting and realistic. The calculated magnetic disturbances produced by the heating are medium-scale one and could be recorded as far as 300 km from heating site. The modelled disturbances in this case show some peculiarities observed in experimental way.

This work has been supported by RFBR (grant 99-05-65209).
 
 
 
 

СРАВНЕНИЕ ЗНАЧЕНИЙ ЭЛЕКТРОННОЙ КОНЦЕНТРАЦИИ ДНЕВНОЙ СРЕДНЕШИРОТНОЙ ИОНОСФЕРЫ ДЛЯ ВЫСОТ 50 - 60 КМ, ПОЛУЧЕННЫХ ПО СДВ-ДАННЫМ И РАССЧИТАННЫХ ПО ФОТОХИМИЧЕСКОЙ МОДЕЛИ

А.Б. Орлов, А.Е. Пронин, А.Н. Уваров (НИИ Радиофизики СПбГУ, Санкт-Петербург)
Г.А. Петрова (Полярный геофизический институт, Мурманск)

Значения электронной плотности N на высотах 50-60 км для околополуденных летних и зимних условий для широты 50 гр., полученные по данным о распространении СДВ-радиоволн для слабой и сильной солнечной активности [1], сопоставлены с результатами теоретического расчета профиля Ne(h). Расчет выполнен на основе фотохимической модели [2] с использованием типовых литературных данных о скорости образования электронов галактическими космическими лучами. Для зимних условий результаты достаточно близки. Однако, для летних условиях значения N, найденные по СДВ-данным, в 6-10 раз превосходят теоретический результат. Знак сезонной вариации значений N, полученных двумя способами оказывается различным: согласно теоретическому расчету зимние значения Ne превышают летние приблизительно в 1,5 раза, тогда как в СДВ-профилях, наоборот, летние значения превышают зимние в 4-8 раз.
Отмеченное рассогласование результатов отчасти может быть обусловлено тем, что концентрация N(h), полученная по СДВ-данным, при h < 65 км является некоторой эффективной характеристикой проводящей среды, содержащей различные заряженные частицы, тогда как результат теретического расчета относится только к свободным электронам. Результаты [3] показывают, что игнорирование ионными концентрациями (до 20000 см-3 на высотах 30 - 45 км) должно приводить при построении профилей N(h) по СДВ-данным к необходимости эквивалентного увеличения концентрации N на высотах 50 - 60 км в 2-3 раз. Из полученных результатов следует, что предполагаемое влияние ионов проявляется главным образом в летних условиях.

[1]. Азарнин Г.В., Колсанов В.А., Орлов А.Б. О  возможной  структуре глобальной модели нижней ионосферы для прогнозирования СДВ. //Проблемы дифр. и распр. волн. Вып. 21. Л., 1987. с. 112-130.
[2]. Петрова Г.А., Брюнелли Б.Е. Модель ионной химии D-области ионосферы //
Препринт ПГИ. 1990. N 90-09-77. Апатиты. КНЦ АН СССР. 46с.
[3]. В.И. Иванов, С.Ю. Ледомская. Эффект влияния ионов на характеристики распространения ОНЧ-радиоволн и параметры шумановского резонанса. // Геом. и аэрономия. 1981. N2. С.298-301.
 
 
 
 

ВЛИЯНИЕ АЗИМУТАЛЬНОГО ММП НА ПРОСТРАНСТВЕННУЮ СТРУКТУРУ F-ОБЛАСТИ ПОЛЯРНОЙ ИОНОСФЕРЫ

Г.И. Мингалева, В.С. Мингалев (Полярный геофизический институт, Апатиты)

Известно, что параметры солнечного ветра, в частности, межпланетное магнитное поле ( ММП ) могут существенно влиять на крупномасштабную картину конвекции магнитосферно-ионосферной плазмы. Поэтому изменения ММП, обусловленные вариациями параметров солнечного ветра, могут оказать влияние на пространственную структуру высокоширотной ионосферы. Влияние азимутальных компонент ММП на пространственное распределение параметров высокоширотного F-слоя уже исследовалось при помощи математических моделей ионосферы, в частности, в работах [1,2]. Однако, применявшиеся для этого модели имели ряд существенных ограничений, например, модель [1] позволяла рассчитывать только электронную концентрацию, а модель [2] хотя и позволяла рассчитывать наряду с электронной концентрацией еще и тепловой режим ионосферной плазмы, но использовала упрощенное задание параметров термосферы.
В настоящей работе приводятся и обсуждаются результаты численных расчетов пространственных распределений электронной концентрации, электронной и ионной температур, а также скорости положительных ионов, которые получены при помощи усовершенствованного варианта математической модели [2], подробно описанного в работе [3].Результаты получены для соответствующих двум разным ситуациям в ММП двух моделей электрического поля конвекции. В обоих случаях вертикальная компонента ММП считается направленной к югу. Азимутальные же компоненты ММП выбираются такими, что горизонтальная проекция вектора ММП считается имеющей азимутальный угол в пределах 270-360 градусов в первом случае и имеющей противоположное направление во втором случае (азимутальный угол в пределах 90-180 градусов). Расчеты проводятся для условий зимы при средней солнечной активности и спокойных геомагнитных условиях.

[1] Гальперин Ю.И.,Зосимова А.Г.,Ларина Т.Н.,Можаев А.М.,Осипов Н.К., Пономарев Ю.Н. Космические исследования,т.18,с.877-898,1980.
[2] Сырникова Т.В.,Мингалева Г.И.,Мингалев В.С.,Власков В.А.,Мизун Ю.Г. Геомагнетизм и аэрономия,т.24,с.311-313,1984.
[3] Мингалева Г.И., Мингалев В.С. В сб.: Моделирование процессов в верхней полярной атмосфере, с. 251-265, Мурманск, 1998.
 
 
 
 

SOLAR ACTIVITY INFLUENCE ON THE SEASONAL VARIATIONS OF THE TEMPERATURE OF THE MESOPAUSE AND LOWER THERMOSPHERE

L.M. Fishkova, N.M. Martsvaladze
(Abastumani Astrophysical Observatory, Georgian Academy of Sciences, Tbilisi, Georgia)
N.N. Shefov (Obukhov Institute of Atmospheric Physics of RAS, Moscow)

The analysis of the long-term measurements of the emission intensities of the atomic oxygen 557.7 nm (~ 97 km), the atomic sodium 589.0-589.6 nm (~ 92 km) and temperature of the hydroxyl emission (~ 87 km) gives a possibility to reveal the distinct seasonal dependences of the correlation between the above-mentioned emission parameters and solar activity level. Estimations of the seasonal variations of the atmospheric temperature at heights 97 and 92 km have been made on the base of correlations between them and emission intensity variations. There are the significant positive correlations between the atmospheric temperature at heights 97-100 km and solar activity during January-May and August-December (r = (0.4-0.7)+/-0.13, tS = 3.3). During summer months June-July the correlation is near zero ( r~0.1). There is a small decrease of the correlation coefficient during period of the fall maximum of the emission 557.7 nm intensity. At heights near 92 km the significant correlation is positive during January-September ( r = (0.4 - 0.6)+/- 0.14, tS = 2.5), during October it changes a sign and there is negative correlation during November-December ( r = - 0.34+/-0.15). At heights ~87 km the correlation between mean monthly increments of the temperature concerning mean annual values and solar activity level is negative during January-March and October-December (r~ - 0.45+/-0.16) and during May-August it is positive (r ~0.49+/-0.17). Correlation of the mean annual values of temperature with solar activity level is positive. It is important to note that periods of decrease of correlation between atmospheric temperature and solar activity accompany by the subsidence of the atomic oxygen layer. It is evident, this phenomenon can be connected with the advantage influence of dynamic processes in the atmosphere.

This work was supported by Russian Foundation of Basic Research (grant of N 98-05-64135).
 
 
 
 

EXPERIMENT ON EFFECTIVE GENERATION OF ARTIFICAL MAGNETIC PULSATION IN Pc1 FRIQUENCY RANGE

A.B. Pashin (Polar Geophysical Institute, Apatity, Russia)
T. Bosinger (University of Oulu, Oulu, Finland)
A.A. Mochalov (Kola Branch of Petrozavodsk State University, Apatity, Russia)

On November 19, 1998 experiment on effective generation of artificial magnetic pulsations in Pc1 frequency range has been arranged. The pump wave has been modulated with three frequencies being 1, 2 and 3 Hz, each modulation frequency was used for 5 minutes. The heating wave frequency was 5.423 MHz, for three modulation cycles the pump wave polarization was Ordinary (o-mode) and then for one cycle was changed to extraordinary (x-mode). This one-hour duty cycle was repeated twice. Ionosphere modification has been produced during time interval 15.30 - 17.30 UT for conditions of well developed D-region. There is a clear decrease of the artificial emission intensity during this experiment due to D-region electron density decay after sunset. Comparison of the Pc1 amplitude with the electron number density in the lower ionosphere measured by EISCAT shows their positive correlation. This experiment gives direct and strong evidence of the conclusion based on the numerical modeling and reported earlier that the fat D-region is necessary for effective generation of the artificial Pc1 pulsations.
 
 
 
 

DEDUCING AURORAL IONOSPHERE AND THERMOSPHERE CHARACTERISTICS USING THE METHOD OF OPTICAL TOMOGRAFY

Zh.V. Dashkevich ¹, V.G. Korotkov ¹, A.V. Roldugin ¹, O.V. Evstafiev¹, T.I. Sergienko ², S.V. Leontyev ^1
1 Polar Geophysical Institute , Apatity, Russia
² Swedish Institute of Space Physics, Kiruna, Sweden

The information on spatial distribution of characteristics ionosphere and precipitation pactirles during auroras can be obtained from series of photometer measurements, that provide us with adequate pattern of tha spatial distribution of the main auroral emission luminosity. Such experiments are carried out, for instance, by the Swedish Institute of Space Physics in Kiruna, according to the ALIS program. Back in February-March 1999, the Polar Geophysical Institute performed an experiment, concerning the ionosphere optical tomography. The objective of the experiment was to deduce the spatial distribution of the volume emission luminosity, following the arc meridional section. We have analysed the data of observations, performed using a chain of three scanning photometers. We have obtained two-dimensional images of auroral arc of the 557.7 nm emission of atomic oxyden and 427.8 nm of molecular nitroden ion, using the computer tomography technique. We have deduced the altitude profiles of the volume emission rate as well as obtained height dependences of ratio of 557.7 nm and 427.8 nm emission intensities. Values of these ratios fall in interval of 6-9 unit, which correlated well with experimental results, obtained by other investigation.
 
 
 
 

QUASI-BIENNUAL VARIATIONS OF THE TEMPERATURE AT HEIGHTS OF THE MESOPAUSE AND LOWER THERMOSPHERE

Kh. Fadel (Swedish Institute of Space Physics, Kiruna, Sweden)
A.I. Semenov, N.N. Shefov, V.A. Sukhodoev (Obukhov Institute of Atmospheric Physics of RAS, Moscow, Russia)

Available data of the regular measurements of the mesospheric and lower thermospheric temperatures for period 1984-1995 covering almost complete solar cycle obtained by the European Incoherent Scatter UHF radar (69.6 N, 19.2 E) have been used for revealed quasi- biennual oscillations.For analysis, the data for quiet geomagnetic conditions have been only used. The seasonal temperature variations from the series of the mean monthly temperature data have been excepted by calculation of the second differences for terms of the series, namely

DeltaT = [T(i)-T(i-1)]-[T(i+1)-T(i)] = 2T(i)-T(i-1)-T(i+1).

where i is a number of year for regarded months. The data obtained after such filtering have used to reveal the quasi-biennual temperature variations during 11-year solar cycle at heights of 107, 97 and 87 km. There is monotone lag (Delta t) of the train waves and decrease of the amplitude of oscillations on change of the height from the top (107 km) to the down (87 km). The estimation of this lag corresponds to rate of vertical propagation of the disturbance about 0.1 cm per sec.

This work was supported by the Russian Foundation of Basic Research (grant of N 98-05-64134).
 
 
 
 

APPLICATION OF LANDAU-ZENER AND ROSEN-ZENER APPROXIMATIONS IN THE CALCULATION OF RATE COEFFICIENTS FOR INTRAMOLECULAR AND INTERMOLECULAR ENERGY TRANSFER PROCESSES OF MOLECULAR NITROGEN

A.S. Kirillov (Polar Geophysical Institute, Apatity, Russia)

The overall rate of the excitation of triplet states of molecular nitrogen in aurora is comparable with the one of ion-electron pair production. The spontaneous transitions between the states cause the radiation of VK, 1PG, 2PG, WB etc. bands. The collisional quenching rates of some triplet states are comparable with radiational ones in the region of lower thermosphere-mesosphere. To calculate the quenching coefficients we have used the Landau-Zener approximation for the case of crossed potential energy curves. Rosen-Zener approximation has been used for the non-crossing case. The probability of the collisional transition between the states is the product of Landau-Zener or Rosen-Zener probabilities and Franck-Condon factors. The coefficients of electronic energy transfer in a collision of two nitrogen molecules have been calculated for both intramolecular and intermolecular processes. The calculated coefficients for the energy transfers A,v'-B,v, W,v'-B,v and for the electronic quenching of A, B states are compared with experimental data. Good agreement has been obtained.
 
 
 
 

THE STUDY OF THE ROLE OF COLLISIONAL PROCESSES IN AURORA OF TYPE B

A.S. Kirillov (Polar Geophysical Institute, Apatity, Russia)

Calculated according to Landau-Zener and Rosen-Zener approximations coefficients for intramolecular and intermolecular energy transfer processes between triplet states of molecular nitrogen have been used in the study of a role of collisional processes in the radiation of First Positive Group bands at different altitudes of polar lower thermosphere and mesosphere. Suggested analytic expressions for the coefficients make it possible to calculate the rates of energy transfer processes for different values of vibrational levels of reagents and products in comparison with the study of Morrill and Benesch (Journal of Geophysical Research, 1996, 101, 261). We have taken into account the collisional energy transfer processes from A,W,B'states to B state. It is shown that there is not a sufficient redistribution in vibrational population of B state at mesosphere altitudes in comparison with lower thermosphere ones. So we have not obtained the suggested by Morrill and Benesch sufficient increase in the populations of high vibrational levels of B state at the altitudes of type B aurora. It is concluded that the primary reason of red lower border of type B aurora is the decrease in the intensity of 557.7 nm green line relative to other emissions at mesosphere altitudes owing to collision quenching of metastable state of atomic oxygen.
 
 
 
 

INVESTIGATION SMALL SCALE IRREGULARITIES IN THE HIGH LATITUDE F REGION IONOSPHERE FROM AMPLITUDE DATA OF SATELLITE RADIO PROBING

E.D. Tereshchenko, M.O. Kozlova, B.Z. Khudukon, O.V. Evstafjev
(Polar Geophysical Institute, Murmansk, Russia)

Small scale irregularities of electron density mostly contribute to the amplitude scintillation of satellite radio signals. Equations are obtained relating to the statistical properties of the scattered amplitude and the parameters of irregularities in the F region high latitude ionosphere. The irregularities spectrum is assumed to obey the power law. It is shown that the variance of logarithmic relative amplitude depends both on the anisotropy parameters of the irregularities and the spatial distribution of density fluctuations. If the irregularities make a statistically homogeneous layer spreading horizontally within a wide enough region, the obtained equations can be used for determining the anisotropy parameters of small scale irregularities. A single ground-based receiver data can be used in this analysis. Examples are shown demonstrating the applicability of this approach in studying small scale irregularities observed in several experiments. The obtained equations are also applied in the analysis of spatially varying distribution of electron density of irregularities measured at a multipoint receiving chain. It is shown that in a series of cases experimental data can be reproduced assuming that the small-scale irregularities make cylinder-shaped structures with varying density fluctuations.