General Information

Accommodation

Author's Kit
and Poster Format

Program

Index to Authors

Registration

Friday 11^th June

Full program for Friday

Fine structure of the global Electric Circuit

S. V. Anisimov
Borok Geophysical Observatory, Russian Academy of Sciences, Borok, Yaroslavl, Russia,
svan@borok.adm.yar.ru

E. A. Mareev
Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod, Russia,
mareev@appl.sci-nnov.ru

1. Introduction.
Over the recent decade many efforts have been undertaken both in observation and theoretical modeling providing substantial progress in understanding the global circuit, especially in terms of its dynamics and structure. According to its classical definition, the global electrical circuit represents the current contour formed by bottom ionosphere and terrestrial surface conducting layers, with thunderstorm generators as the basic electrical sources, and the areas of a free atmosphere as zones of returnable currents [1,2]. Recent knowledge has brought an essentially new approach to appreciate dynamic aero-electrical processes in the Earth's electrical environment [3,4].

2. Experimental Technique and Results.
Extensive databases obtained after long-term ground-based and airborne aero-electrical measurements serve as a background for the monitoring the global electrical circuit. Particularly, a database of the mid-latitude Geophysical Observatory "Borok" (http://geobrk.adm.yar.ru:1352) can contribute substantially to the study of the Earth's electromagnetic environment. As an example of case studies, figure 1 shows a fragment of amplitude-time registration of geophysical fields, including the atmospheric electric field and current, at the "Borok" Geophysical observatory for the magnetic storm on 28-31 March, 2001. The electrostatic generator ("field mill") is used for precise observatory measurements of the atmospheric electric field. The horizontal long-wire antenna is mounted for vertical electric current measurements. The remote receiving of electric field variations is carried out by means of "field mill" lines for aeroelectrical structure detection [4].

3. Discussion.
The analysis of atmospheric electric field allows us to represent the global electric circuit as an aggregation of structures with different spatio-temporal scales. These structures are generated by troposphere-lithosphere (thunderstorms and lightning, earthquakes, fogs) and space sources of quasi-DC electric field (such as the Forbush effect, solar cosmic rays, magnetic convection, field-align current). Global, regional and local effects of these sources form the hierarchy of spatial scales of aeroelectrical structures. The energy and evolution of such structures are defined by efficiency of origins and physical property of weakly ionized quasi-neutral atmosphere with inhomogeneous electrical conductivity in the external magnetic field. The paradigm of structures aggregation of aeroelectric field enables researches with a deep insight into the main components of the global electric circuit and their interconnections with the middle-latitude aeroelectric field.

References:

1. Bering E.A. III, Few A.A., Benbrook J.R. The global electric circuit // Physics Today. 1998. October, P.24-30.
2. Rycroft M., Israelson S., Price C. The global atmospheric electric circuit, solar activity and climate change // J. Atmos. Solar-Terr. Physics. 2000. P. 1563-1576.
3. Anisimov S.V., The global electric circuit and low atmospheric electricity, in Proc. Conference of the Russian Foundation for Basic Research - "Geophysics from XX to XXI century", Moscow, Russia, 8-10 October, 2002.
4. Anisimov S.V., Mareev E.A, Bakastov S.S., On the generation and evolution of aeroelectric structures in the surface layer, J.Geophys. Res., 104, D12, 14359-14367, 1999.

Thunderclouds in the solar-terrestrial weather climate relationship

V.I. Ermakov
Central Aerological Observatory of Rosgidromet, Dolgoprudny, Moscow region

Yu.I. Stozhkov
Lebedev Physical Institute, Russian Academy of Sciences, Moscow

Dr. Victor I. Ermakov, Dr. Yuri, I. Stozhkov
Lebedev Physical Institute, Leninsky Prospect,
53 119991, Moscow, Russia
stozhkov@fian.fiandns.mipt.ru
stozhkov@fiand.msk.su
tel.: 7 095 485-42-63
fax: 7 095 408-61-02

The variations of the electric field strength E on the Earth's surface reflect the thunderstorm activity changes. Reiter gives the relationships of E with solar flares. He analyzed 125 events for the period of 1962-1971 when solar flares were observed near central solar meridian between 20œå and 20œW [Reitrer R. Phenomena in Atmospheric and Environmental Electricity. Amsterdam: Elsevier, 1992, 541 p]. He found that the value of E increased in a period of a few days before solar flare occurred, reached maximum in two days after flare event and dropped down to the averaged value during several days. The solar flare duration does not usually exceed tens minutes and it cannot influence on the daily means of E. However, the most of solar flares occurs inside of the active regions. It means that active regions crossing central meridian of the Sun influence on the thunderstorm activity and, accordingly, on the value of E. The fact of 2 days delay between the solar flare appearance and E increase gives evidence that corpuscular (not electromagnetic) radiation of active region propagating from the Sun with the velocity from several hundreds up to about one thousand km/s influences on thunderstorm activity. In polar coordinates the dependence of E from solar flare longitudinal position was calculated for the 125 events mentioned above. This dependence has a lobe with a width about 70œ at the level 0.5. It represents a directional pattern of corpuscular flux propagation from the solar active region.

Measurement of the mobility of air ions as a source of information for the study of aerosol generation

Jyrki M. Mäkelä,
Institute of Physics, Tampere University of Technology, Finland

Jaan Salm,
Institute of Environmental Physics, University of Tartu,
18 Ülikooli St., Tartu, 51014, Estonia
Phone: +372 7 375 555, FAX: +372 7 375 556, E-mail: Jaan.Salm@ut.ee

Vladimir V. Smirnov, and Aleksei A. Pronin
Institute of Experimental Meteorology, Obninsk, Russia

Ismo Koponen,
Department of Physics, University of Helsinki, Finland

Jussi Paatero,
5Finnish Meteorological Institute, Helsinki, Finland

Beside an effect on atmospheric conductivity, the intermediate ions can play the key role in the chain of hypotheses connecting cosmic rays, atmospheric ionization, aerosol generation, CCN formation, and global albedo. The mechanism of atmospheric aerosol generation is still an enigma and it has become a focus of research efforts in recent years. Four hypotheses have been proposed as the mechanism: homogeneous nucleation of a binary vapor system, ion-induced nucleation of vapors, ternary nucleation of sulfuric acid-water-ammonia, and recombination of cluster ions. In experimental study, the nanometer-sized particles should be measured. Since conventional aerosol particle sizers measure particles with diameters above 3 nm, but air ion mobility spectrometers measure them above 0.3 nm, the usefulness of mobility measurements is obvious.

Large-scale measurements were performed in Southern Finland during March-April 2000, at the annual maximum of the new particle burst occurrence. The results were obtained using aerosol size spectrometers with different pre-charging conditions plus measurements of air ion mobility distribution and of small, intermediate and large ion concentration, supported by additional measurements of air conductivity, radon concentration, hard radiation intensity, trace gas content, and a comprehensive set of meteorological parameters. The experiments with a systematic charger/no charger arrangement for the ultrafine aerosol and with supporting extensive atmospheric ion measurements were performed for the first time. Since radon concentration, small ion concentration and aerosol size distribution were simultaneously measured the steady state ionization balance equation has been experimentally checked.

Very distinct nucleation events were recorded on 5 days and moderate events on several other days. The nucleation bursts were more intensive at low concentration of coarse aerosol. The mobility distributions measured by two identical spectrometers with bipolar pre-charging and without charging coincide well. Significant deviations from steady state charge distribution toward excess or deficit occurred only in the fractions of smallest particles during few nucleation events. The results suggest that different nucleation mechanisms can take place in the atmosphere.

Global electric circuit as an open dissipative system

E. A. Mareev
Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod, Russia,
E-mail: mareev@appl.sci-nnov.ru

S. V. Anisimov
Borok Geophysical Observatory, Russian Academy of Sciences, Borok, Yaroslavl, Russia,
E-mail: svan@borok.adm.yar.ru

Recent experimental and theoretical studies make it possible to analyze the global electric circuit as a hierarchy of multi-scale dissipative systems. We consider the atmospheric part of the global electric circuit as a thermodynamically open system driven by the external sources of energy. The main contribution stems from the solar radiation which is partially absorbed by the land, ocean and atmosphere causing convective motion, winds and water phase transformations and accompanying by the electrical energy generation in the atmosphere. Other potential sources of energy are the geothermal energy flux, solar wind and galactic cosmic rays.

A solar radiation flux equal in average 1.37·10³ W/m² is partly transformed to the quasi-electrostatic energy of the circuit itself and large-scale electric field structure of thunderstorms, mesoscale convective systems, ordinary cloud and fog systems. This energy is dissipated through the fair-weather discharge current of the atmosphere, cloud-to-ground lightning, intra-cloud and high-altitude discharge. We present the estimations for the energy input into the large-scale field growth, fine structure generation and micro-scale electric field perturbations caused by highly charged hydrometeors, as well as for the dissipation rate due to noted discharge processes.

The energy flow from global to local scales through the atmospheric electric circuit is accompanied by the generation of multi-scale dissipative structures [1], including fine electrical structure of thunderstorms, clouds and aeroelectric structures in the boundary layer. We consider briefly the mechanisms of dissipative instabilities leading to these structures generation, nonlinear structures themselves and electric energy input to them. In particular, analytical solutions describing the formation of dynamical structures for electric field and space charge density in the boundary layer have been found. Under some simplifications this model leads to the modified Burgers equation [1] for the nonstationary space charge density perturbations of the finite magnitude with the electro-kinetic Reynolds number as a control parameter.

A thunderstorm as a generator of the global circuit is a key element in the considered system. We have investigated the evolution of electric field and space charge of a thunderstorm cloud in the framework of a diffusion equation for the electric field, which has auto-wave solutions, describing the dynamics electric charge regions separated in the cloud space. Asymptotic values for the velocity and thickness of the space charge front has been found, controlled by the diffusion and parameters of the separation and dissipation currents. The estimates of the electrostatic energy growth rate for a thunderstorm cell at the stage of its intensive development are performed [2]. Further progress in understanding the global circuit requires also to study the role of lightning induced transients in the global circuit dynamics, including transient luminous events in the middle atmosphere [3].

References:

1. Mareeva O.V., Mareev E.A., Israelsson S., Anisimov S.V., Synergetic models of space charge structures in the atmosphere, Proc.11th Int. Conf. Atm. Electr., Guntersville, P. 614-616, 1999.
2. Mareev E.A., Sorokin A.E., Autowave regimes of thunderstorm electrification, Radiophys. Quantum Electr., V.44, N1-2. P.148-162, 2001.
3. Smirnova E.I., Mareev E.A. and Chugunov Yu.V., Modeling of electric field transitional processes, Geophys. Res. Lett., V.27, N23. P.3833-3836, 2000.

FDTD analysis of Schumann resonances for realistic subionospheric waveguide models

Takuya Otsuyama,
The Univ. of Electro-Comm.
Sankosha Co.

Daisuke Sakuma, Masashi Hayakawa,
The Univ. of Electro-Comm.

The space between the ground and ionosphere is known to act as a$B!!(Bresonator for extremely low frequency (ELF) waves. Lightning discharges$B!!(Btrigger this global resonance, which is known as Schumann resonances at$B!!(Bthe frequencies of 8, 14, 20 Hz etc. Even though the inhomogeneity (like day-night asymmetry, local perturbation etc.) is important for such subionospheric ELF propagation, the previous analyses have been made inevitably by some approximations because the problem is too complicated to be analyzed by any exact full-wave analysis. This paper presents the first application of the conventional FDTD (finite difference time domain) method becoming very popular in computational electromagnetics to such subionospheric ELF propagation and resonances, in which any kind of inhomogeneities of the ionosphere can be included in the analysis. We present some computational FDTD results for the global cavity with realistic day-night asymmetry, with a particular emphasis on the diurnal variation of Schumann resonance intensity. Those diurnal variations of Schumann resonances in the vertical electric field and horizontal magnetic fields are found to be in good agreement with the observed ones, and this suggests a potential future use of this computational FDTD method for more detailed analyses in ELF wave propagation.

Atmospheric electric field effects due to the April 2001 solar proton event

O.I. Shumilov, E.A. Kasatkina, A.G. Struev
Polar Geophysical Institute of Kola Science Center RAS, 184209 Apatity, Russia;
e-mail: oleg@aprec.ru

O.M. Raspopov,
St.-Petersburg Filial of IZMIRAN, St.-Petersburg, Russia

The April 15, 2001 solar flare is one of the most powerful events recorded over the last 25 years. The flare was classified as an X14 on the scale of solar flare strengths and followed by a powerful solar proton event of Ground Level Enhancement (GLE) type. Of course, such event must be resulted in a large disturbance of global atmospheric electric circuit. In this paper the measurements of vertical electric field and atmospheric conductivity made by a high-latitude computer-aided complex on 15 April 2001 in the auroral zone (Apatity, geomagnetic latitude: 63.8) are presented. A significant disturbance in atmospheric electric field has been observed at the time of solar flare. It is interesting to note that the beginning of electric field perturbation has been detected a some time (about half an hour) ahead of the X-ray burst (13.50 UT) and GLE onset (14.05 UT, according to the data of Apatity neutron monitor). Measurements of atmospheric electric field at St.-Petersburg (geomagnetic latitude: 56.1) showed a similar disturbance at the same time. This permits us to consider experimental effect observed as a global one. A possible explanation of experimental results based on the method of "labeling" the corresponding magnetic field line at the earth surface with its coronal connection longitude is discussed.

 Outstanding problems concerning the global electric circuit

Brian A. Tinsley
University of Texas at Dallas, Richardson, Texas, USA

We revisit the problems related to the discrepancy between the observed amplitudes, of responses of the global circuit to inputs related to solar activity, as compared to modeled amplitudes. The solar activity modulates the latitude distribution of the cosmic ray flux. It also modulates the X-ray flux at middle to high latitudes in the stratosphere,that is due to Bremsstrahlung from MeV electrons precipitating from the magnetosphere. Both ionizing inputs modulate the latitude distribution of vertical column conductivity in the global electric circuit.
The discrepancies between observations and models increase with increasing content of stratospheric volcanic aerosol. One possibility for resolving the discrepancies is that the column resistance of the stratosphere and upper troposphere is greater than previously calculated, due to the presence of stratospheric aerosol and very thin clouds near the tropopause. The increase would depend on the aerosol content, and would at times bring the stratospheric column conductivity to a level that was not negligible with respect to the tropospheric column conductivity .

Last Update : May 21, 2003
[ ICAE 2003 Home Page] - [ ICAE Contacts ]