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Wednesday 11^th June

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 Atmospheric Ions

H. Tammet
Institute of Environmental Physics, University of Tartu, Estonia

The amount of publications about atmospheric ions has not increased in the last decade. During the review period of 1999-2002, the most popular topic was ion-induced nucleation. Considerable progress was achieved in the understanding of the chemical composition of atmospheric cluster ions, in the study of the mobility distribution of atmospheric ions, and in the development of measuring methods.

Electrodynamics of the Fog

S. V. Anisimov, A. E. Sorokin, N. M. Shikhova, E. M. Dmitriev
⁾Borok Geophysical Observatory, Russian Academy of Sciences, Borok, Yaroslavl, Russia,
E-mail: svan@borok.adm.yar.ru

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

1.Introduction.
Fog is a wonderful natural laboratory for the study of aero-electric state of the boundary layer in the presence of aerosol particles [1,2]. On the other hand, it is an important object of long-term rather controversial investigations. The paper presents a detailed description of electrical and dynamic properties of the fog based on natural observations and theoretical calculations.

2.Technique of Experiment and Results.
The spectra of electric field pulsation (f @  0.001-1 Hz) and simultaneous measurements for vertical component of electric field and the current have been cited. The structural-temporal profiles of the electric-field dynamics under fog conditions were studied. The calculations were made using the results of synchronous observations of the electric field at nine points spaced by distances from 15 to 450 m. An example of a giant aeroelectric structure registered during the fog 15-16 September 1999 is presented in Fig. Results of the studies allow us to distinguish between two types of the fog: first one is characterized by presence of large aeroelectric structures, second one - by the random structural-temporal variations. It is found that the energy of aero-electric pulsations under fog conditions is about an order of magnitude greater than the energy of electric-field pulsations under the fair-weather conditions. The aero-electric field pulsations have power-law spectra under fog conditions. It has been shown that fog brings to the current density reducing, as a rule with current's sign change.

3.Theoretical model.
The basic system of electrohydrodynamic equations for the fog description has been formulated. Numerical calculations concerning influence of the fog particle and air ionization parameters to diffusive particles charging have been carried out. Stationary height distributions for the fog particles charge, electric field and light ion concentration have been numerically investigated. We discussed possible generation mechanisms for the electric field fluctuations spectrum, their relation with the pulsation of the density of electric charge taking into account the turbulence of neutral gas and aeroelectric structures.

4. References

1. Anisimov S. V., Mareev E.A., Sorokin A.E., Shikhova N.M. and. Dmitriev E. M, Electrodynamical properties of the fog, Izvestiya, Atmospheric and Oceanic Physics, vol. 38, N5, p. 1-15, 2002.
2. Anisimov S.V., Sorokin A.E., Mareev E.A., Horizontal long-wire antenna as a fog electrical properties analyzer, in Proc. of Conference on fog and fog collection. St.John's, Canada, p. 473-476 July 2001

Ionospheric Potential Variation from Temperature Change over the Continents

Ralph Markson
Airborne Research Associates, 46 Kendal Common Road, Weston, MA 02493
rmarkson@attbi.com

Since global thunderstorm activity and electrified deep convective shower clouds maintain the current flow in the global circuit and ionospheric potential (Vi), and convection is driven by temperature, the variation of Vi should be a measure of the variation of global temperature, or at least global temperature at tropical and equatorial latitudes where most deep convection occurs. In a continuation of an investigation of the possibility of monitoring changes in global temperature with (Vi) measurements, 20 balloon soundings made over the period of one month were compared with surface temperature across tropical and equatorial Africa and South America. A possible advantage of this approach is that these latitudes, which are vital in controlling global climate, have few meteorological reporting stations. Satellite temperature data have limitations related to the effects of clouds and aerosol on calibration and sampling problems. In contrast, meteorological processes in these latitudes control Vi. The present complete analysis, extending an earlier preliminary study, was a series of lag correlations with one hour temporal resolution from 10 hours before until 4 hours after the Vi sounding times near mid-day and afternoon in Africa and South America.

The findings of this research are:

1. Vi is controlled by temperature over the continents. Correlation of Vi and surface temperature from 15N to 30S from 10 hours before until 4 hours after the Vi measurements show there is a highly significant (p>99%) positive correlation of Vi and temperature for the morning and early afternoon hours which rapidly becomes a negative correlation (p>99%) in the mid- to late-afternoon.
2. The possible explanation for the positive correlation becoming negative is that after formation of deep convection due to heating in the morning and mid-day, cirrus blowoff and mid-altitude residue clouds screen solar radiation causing a cooling of the air at and near the ground in the mid-and late-afternoon hours. Another factor is that outflows from earlier thunderstorms enhance thundercloud development later in the day. Thus, earlier heating causes more thunderstorm activity in the afternoon and higher Vi values despite cooler temperatures in the afternoon and evening.
3. These findings suggest a negative feedback process that would tend to stabilize global temperature - more heating causes more thunderstorms resulting in more clouds which screen radiation cooling the ground and lower atmosphere.
4. The sensitivity of Vi to temperature is such that a 1% change in temperature implies a 20% change in Vi. Assuming a +/- 3% precision in the Vi measurement, it should be possible to detect variations in global tropical temperature of ½ degree Centigrade.

Diurnal Variation in the Concentration of Air Ions of Different Mobility Classes at a Rural Area

Urmas Hõrrak, Jaan Salm, and Hannes Tammet
Institute of Environmental Physics, University of Tartu, 18 Ülikooli St., Tartu, 51014, Estonia
+372 7 375 555
+372 7 375 556
Jaan.Salm@ut.ee

Diurnal variation in the concentration of air ions of different mobilities is studied on the basis of 8900 hourly average mobility distributions measured in the mobility range of 0.00041-3.2 cm²V^-1s^-1 (diameter range 0.36-79 nm) at Tahkuse Observatory, Estonia, in 1993-1994. The average diurnal variation in the concentration of cluster ions was typical for continental stations: the maximum in the early morning hours and the minimum in the afternoon. The explanation is proposed by diurnal variation in radon concentration of the air. The variation pattern for big cluster ions (0.5-1.3 cm²V ^-1s ^-1) was different when compared with small cluster ions (1.3-3.14 cm²V ^-1s ^-1).

The size distribution of aerosol ions (intermediate and large ions) in the range of 1.6-22 nm is strongly affected by nucleation bursts of nanometer particles occurring occasionally around noon depending on meteorological conditions. In the burst days, the maximum concentration of intermediate ions or nanometer particles (1.6-7.4 nm) was found about the noontime, and that of light large ions (7.4-22 nm) about 2 hours later.

The concentration of heavy large ions (charged Aitken particles of diameters 22-79 nm) is enhanced in the afternoon that is explained by the bursts of nanometer particles and subsequent growth of particles by condensation and coagulation to large sizes. If the burst days were excluded, the Aitken particle concentration increased during night in the warm season probably due to radiolytic processes initiated by radon decay. During the cold season, the average diurnal variation in the concentration of charged Aitken particles was essentially different, and all the classes of aerosol ions (2.1-79 nm) showed similar average diurnal variation with the minimum at 6 LST; exceptions are rare nucleation burst days. The concentration of nanometer particles had the maximum in the afternoon before the Aitken particles reached the maximum in the evening around 20 LST. Variation of different classes of air ions provides information about different processes in the atmosphere.

Long term variations of some atmospheric electricity, aerosol, and extra terrestrial elements at Swider Observatory, Poland

Marek Kubicki, Stanisaw Michnowski, Stanisaw Warzecha
Institute of Geophysics, Pol..Ac Sci., Warsaw

B. Mysek- Laurikainen
The Andrzej Soltan Institute for Nuclear Studies, Otwock -wider  

Long term registration of the electrical conductivity, l , electric field, E, aerosol concentration, A, and some radioactive and meteorological elements carried on at the ground in the performed land geophysical observatory at Swider ( 52 ⁰07'N, 21⁰15' E) were examined on the basis of wavelet analysis, together with simultaneous data on cosmic rays and solar activity. This examination was for the years 1965-2000 with the use of multiresolution decomposition into smooth and detailed components. The data used now were the values of fractional deviation of the mean monthly values from the mean value for whole examined period. This was done in order to remove the seasonal and daily variations obscuring the important features of the long data series. All data were taken only from the periods of fair weather, which were possible to be discerned due to continuous meteorological station service in the recording site.

At first, the smooth S6components, which correspond to slow oscillations at time scales longer than 64 months, i.e. longer than 5.3 years are considered. The variations in E, l , A in this range of periods were compared with corresponding long period variations of radioisotope Be7 concentration, recorded in the air layer at the ground in Swider, and also with changes of cosmic ray intensity, I, and sunspot number, N.

The course of long term air conductivity variations shows the drastic decrease in years 1965-1969 during the nuclear tests in the atmosphere at almost steady level of the aerosol concentration in this time. The maxima of electric field variations, in the range of S6 periods, taking place in the years 1980-82 and 1990-92 correspond to maxima in sunspot numbers in time of concurrent minima in l changes, also the minimum in E is seen strongly in the years 1985-1987 at minimum of solar activity. The long term changes in E during the years 1971-1991 are in strong positive correlation with corresponding changes in l at the slight changes in A. However, in next years there appears negative correlation between E and l at small changes in E.

Minimum in Be7 concentration in the air surface layer in 1995-96 is accompanied with the corresponding minimum of sunspot activity. In the following years the noticed decrease in l corresponds to decrease in cosmic rays activity and Be7 concentration.

The variations in the range of detailed D2, D5 components of smaller periods, show smaller and complex not clear mutual correlation of the examined E, l , and A. The occurrence and intensity of these correlation depends on atmospheric aerosol concentration which is affected by human activity.

The very high correlation between long term variations of atmospheric electricity elements and corresponding changes of cosmic ray and solar activity changes show on of extra terrestrial influences on the lower atmosphere. Wavelet analysis may be useful in studies of atmospheric electricity relations with extra terrestrial and human activity factors which are not to be neglected in studies of long term climate changes.

References:

1. J.L. Borkowski, Variations of the UV-B radiation, ozone and cloudiness at different time scales: A wavelet analysis. Acta Geophysica Polonica , Vol.50-No.1,2002, pages 109-117.
2. S. Michnowski , Solar wind influences on atmospheric electricity variables in polar regions, Journal of Geophysical Research, vol.103, No. D12,Pages 13,939-13,948, June 27,1998
3. S.Warzecha , M.Kubicki, Publications of the Institute of Geophysics Polish Academy of Sciences, Results of atmospheric electricity and meteorological observations S. Kalinowski
Geophysical Observatory at wider 1965 -2000.

Variations of Atmospheric Electricity Elements in Polar Regions related to the Solar Wind Changes

S. Michnowski, M.Kubicki, J. Drzewiecki,
Institute of Geophysics, Pol. Acad. Sci., 01-452 Warszawa, Poland,

S. Israelsson,
Meteorology Geocentrum, Uppsala University, Villavaegen 16, 752-36 Uppsala, Sweden,

N. Kleimenova, N. Nikiforova, O. Kozyreva,
Institute of Earths Physics, R.A.S., B. Gruzinskaya 10, Moscow, Russia

Electric field (Ez) and vertical Maxwell current density (Jz) at the ground are unquestionably in intrinsic physical dependence upon electric potential of the ionosphere and electrical conductivity of the atmosphere above the measuring site. Although the ionosphere potential and atmosphere conductivity variation in polar regions fundamentally depend on solar wind changes, the response in high latitudes of the Ez and Jz to solar wind variability has been for a long time considered doubtful. Diversity of the solar wind influences and problems with separating the notorious noise of meteorological origin in local and global thunderstorm activity scale, still are difficult obstacles in gathering the knowledge about response of electrical elements of the lower atmosphere to the magnetosphere and ionosphere changes induced by solar wind. Such a response has been statistically demonstrated, e.g., strong influence of IMF components of solar wind on Ez recorded in polar site is shown by comparing differences between the actual Ez daily changes and the fair weather average Ez diurnal variation which followed there the Carnegie curve (Frank-Kamenetsky et al., 2001). The cases of Ez and Jz reaction to magnetosphere and ionosphere changes have been previously reported but most often without detailed references to the situation produced by solar wind and Earth's magnetic field interaction and to the global electric circuit interference (Apsen et al., 1988; Michnowski et al., 1991).

In this paper we present events that may give evidence for possible solar wind effects on Ez and Jz as observed at the ground in Polish polar station Hornsund (Spitsbergen: j =77.0° , l =15.5° ) at specific helio-geophysical circumstances. A cosiderable number of such events have been recorded during fair weather conditions with a view to the paucity of such meteorological conditions. Some selected individual cases are presented and preliminarily discussed. Their examination was performed using the station recordings of the geomagnetic field components, ionosphere absorption measured by riometer, and a set of meteorological parameters. The data have been used, moreover, from IMAGE net of stations with simultaneous magnetometer and riometer recordings for an estimation of position of electrojet and the data from satellite recordings of solar wind parameters, which allow also to estimate approximately the extra-troposphere changes of ionosphere potential above the station.

The examined variations of Ez extend the results reported by Apsen et al. (1988) by showing their dependence in the sign and magnitude during the preliminary and expansion phase of substorms upon station location in respect to actual state of magnetosphere-ionosphere system. E.g., it was noticed that in the expansion phase, the Ez values decrease with the growing indications of riometers which correspond to injection of energetic electrons, increasing the conductivity in the ionosphere and partly of the atmosphere below.

The dynamic spectral analysis of the examined variables shows common properties or differences in the electric field fluctuations with the associated magnetic pulsations in relation to field aligned currents and the phase of substorm development (Kleimenova et al., 1995). Distinct relation of the Ez and Jz fluctuations with the oscillations of ionosphere absorption was found during expansion phase of substorms.

At the sudden commencement of strong magnetic storms, the positive and large Ez enhancements were recorded after large jump in the interplanetary magnetic field (IMF) and other parameters of solar wind. E.g. on July 15, 2000, after such very large change, the Ez and Jz jumped during fair weather to the values more than two and half times larger than the previous quiet values persisting for a long time. Hornsund, during very large Bz component of IMF, was located then under the projection of polar cap region (Nikiforova et al., 2002).

A further extension of the analysis of Ez and Jz variations in polar regions, by the use of geospace and global electric circuit data, can bring a better understanding of the observed couplings of the lower atmosphere with the upper atmosphere regulated by solar wind changes.

References:

References: Apsen A.B., Ch. Konnidi S.P., Chernysheva D.N., Chataev D.N. and Sheftel V.M., Magnitosfernye Effecty v Atmosfernom Elektrichestve, Nauka, p.140, 1988.

Frank-Kamenetsky A.V., Troshichev O.A., Papitashvili V.O., Bering E.A., French W.J.R., Variations of the atmospheric electric field in the near pole region related to the interplanetary magnetic field, J.Geophys.Res., V. 106, p.179-190, 2001.

Kleimenova N.G., Michnowski S., Nikiforova N.N., Kozyrieva O.W., Dlinnopieriodnye geomagnitnye pulsatsii i fluktuatsii naprazennosti elektricheskogo polia atmosfery na shirotakh poliarnogo kaspa, Geomagn. Aeronom. V. 35, s. 38-48, 1995.

Michnowski S., Szymanski A., Nikiforova N.N., Kozyreva O.V., Zielkowski K., On simultaneous observations of geomagnetic and atmospheric-electric field changes in Arctic station Hornsund, Spitsbergen, Publ. Inst. Geophys. Pol. Acad. Sci., D-35(238), p.83-96, 1991.

Nikiforova N.N., Kleimenova N.G., Kozyreva O.V., Kubicki M., Michnowski S., Polar cap atmospheric electric field response to the sudden commencement of the Bastille day magnetic storm, Problems of Geocosmos, June 3-8, St. Petersburg, p.58, 2002.

Last Update : June 3, 2003
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