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Statistical Characteristics of Air Electric Conductivity in Dusheti |
| A.G.Amiranashvili,
L.L.Kalaijeva, N.D.Karauli,
A.T.Khunjua, A.G.Nodia, J.I.Vachnadze |
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Results of statistical analysis of mean monthly, six month and yearly values of total air electric conductivity Y in Dusheti have been considered (in latitude 42.08 degrees, in longitude 44.7 degrees, 900 m latitude a.s.l.). An observation period makes 25 years, from 1966 to 1990. A measurement unit Y is given in 10^-15 ohm m, omitted further to be more convenient. Data on intra-yearly variations of mean air electric conductivity values in different time periods have been presented ; analysis of stability of correlation links of air electric conductivity with each other has been conducted by months and seasons of the year; presence of negative trends of Y values for all months of the time period under investigation, has been revealed. In particular, it has been received that:
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The possible role of fair weather electricity on the charging of wind-dispersed pollen |
| G. Bowker |
| Wind-pollinated plants reproduce by capturing pollen suspended in the air. A charged airborne particle in an electric field experiences an electrostatic force equal to the product of its charge and the electric field at its location. Pollen grains may be charged and electric fields are present around plants due to the ambient fair weather electric field. Consequently, electrostatic forces might affect pollen capture. This study investigates the electrostatic fields around plants, determines the charges on pollen for seven plant species, and predicts some situations where electrostatic forces may influence the capture of pollen. |
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Relationship between the atmospheric electric field (A.E.F.) and air pollution in the lower levels of the atmosphere |
L. Delgado Martín,
E. García Diez, F. de Pablo Dávila
and L. Rivas Soriano Departamento de Física de la Atmósfera, Facultad de Ciencias, Universidad de Salamanca, Spain |
The relationship between atmospheric electric field (AEF) and air pollution is analysed for Salamanca, Spain, between 1996 and 2000. The results show a high correlation between AEF normalized and concentration of neutral pollutants. This correlation values are higher in winter months than in summer ones. We think that AEF influences the pollutants concentration due to their electric properties (like their dipole moments). |
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Analysis of composite mobility peak for multiple atmospheric ions in equilibrium |
| Koichi Iinuma and Shunsuke Uchida |
| A general solution of coupled diffusion-reaction equations governing the spatiotemporal evolution for the number densities of an arbitrary number of inter-reacting ionic species in the atmosphere has been analytically derived in a framework of particle non-conservation system, using a Fourier transform technique and matrix algebra (1). For IMS/MS analysis, the general solution enables the rigorous analysis of non-homogeneous gas-phase reactions for multiple ionic species intertwined with their drift and diffusion process in a complex way. Based upon this solution, we also developed the steady state solution for all the ionic species approaching dynamic balance between their transport and reaction process. The steady state solution describes a set of similar Gaussian profiles with the same quasi-equilibrium (dynamic equilibrium) mobility and diffusion coefficient on the same peak position (2). This is the analytical profile of the famous composite mobility peak predicted by Mohnen et al. in the mid-1970th. Theoretical formulas for the mobility, the diffusion coefficient, and the equilibrium number densities of all the ionic species in equilibrium have been obtained by introducing the transport-reaction matrices and their determinants. A new analysis method, founded on this steady state solution, has been developed to determine the mobility of each ionic species independently under equilibrium condition, where all the ionic species appear to have the same mobility with the same core ions (ion family). The composite mobility peak for ammonium- as well as hydronium-based ions-family measured by a few experimental groups using IMS/MS apparatus has been examined in the present analysis. References:
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On the Atmospheric Response to Solar Cosmic Ray Events |
| Z. Kobylinski S. Michnowski |
| Possible atmosphere responses to different agents of solar variability cannot be directly explained only by changes of energy flux from the Sun. The changes in total solar irradiance (1.36 × 103 W/m2), providing a variable heat input to the ground surface, varies only by about 0.1% in the decadal and shorter-term variations (Frohlich and Lean, 1998). The variation in solar ultraviolet flux that could cause changes in stratospheric dynamics and be coupled with troposphere dynamics, is also very small, not bigger than 0.5 % (Rottman and Woods, 1999). The flux of energy of galactic cosmic ray (GCR) particles, equal to 10-5 W/m2, is of greater variability. The GCR particles, which are essentially the main source of atmospheric ionization in the stratosphere and troposphere down to about 2 km above the ground, are modulated by changes in the solar wind and vary on different time scales, for instance, 11- year modulation of GCR of energy ~ 1 GeV changes their flux by factor 2. The galactic radiation is occasionally supplemented by solar energetic particle events (SEP) coming in part from solar flares. In the latter case, the majority of SEPs is accelerated by shock waves driven by coronal mass ejections. The ground level enhancement (GLE) of energy flux is then also not much higher, for example on 15.08.1959 it was equal 7 × 10-2 W/m2. Although this energy is smaller at least about 107
times than the energy involved in troposphere dynamic processes, the observational
and theoretical suggestions have been made about possible role of cosmic
charged particle flux in atmosphere dynamics through modulating the global
electric circuit (Tinsley and Dean, 1991). The current flow in this circuit
between the ionosphere and the ground surface reponds to the energetic
particle flux changes. The changes in this current affect microphysical
processes in clouds, which govern the ice production changes and the subsequent
changes in cloud albedo, precipitation, and latent heat release, affecting
troposphere temperature and dynamics. The release of such heat in warm
core cyclones and their intensification by the free energy of horizontal
wind shear has been proposed as an explanation of the significant correlation
found by Wilcox and others between the strength of cyclones and cosmic
ray intensity changes. References: Rottman G., Woods T., IUGG Meeting, Birmingham, Program
Book, 139, 1999 |
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Ion-induced nucleation of sulphuric acid and water: |
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M. Noppel M. Kulmala and H. Vehkamäki |
| Cosmic radiation and the decay of radioactive substances generate the ions, which can serve as condensation centres. Sulphuric acid and water are considered as the major species that participate in new particle formation in the atmosphere. One of the difficulties for predicting the nucleation rate of sulphuric acid and water vapours, compared with other binary systems, proceeds from the tendency of sulphuric acid to form hydrates (small clusters of acid and water molecules) in the gas phase. The hydrates stabilise the vapour. Their formation energy is negative, and therefore it is energetically more difficult to form a critical nucleus out of hydrates than out of free acid molecules. In early papers the influence of sulphuric acid hydrates on ion - induced nucleation of sulphuric acid water was not taken into account, or it was not done in a proper way. In the present paper the effect of hydration of gas phase acid molecules on ion - induced binary nucleation of sulphuric acid and water is considered. The classical nucleation theory is used. The hydration model based on the data of ab initio calculations and experimental data of acid vapour pressure above aqueous solutions of sulphuric acid is applied. |
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Electrical conductivity near the Earth's surface: |
| K. Nagaraja, Prasad
B. S. N., N. Srinivas and M.
S. Madhava |
| The electrical conductivity is one of the important parameters for understanding the electrical nature of the earth's atmosphere. This parameter is sensitive to the presence of aerosols. Thus, the aerosol loading has a bearing on the conductivity of the atmosphere. The aerosols reduce the conductivity of the atmosphere by (i) converting the highly mobile small ions into less mobile aerosol ions through ion - aerosol attachment (coefficient b ) and (ii) neutralizing the small ions through the aerosol ion - small ion recombination (coefficient a s). Another process that makes the ion-aerosol attachment rate faster is the charged aerosol - aerosol recombination (coefficient aa). However, a a is small compared to b and a s. There have been no reports on modeling study of the conductivity in the lower part of the troposphere, in particular near the surface. Modeling for this region requires, ionic aerosols, in addition to the molecular ions. Based on this, a Simple Ion-Aerosol Model (SIAM) is proposed.
Simple Ion-Aerosol Model used in our study is as shown in figure. It involves primary ion pair production rate (q) due to surface radioactivity and cosmic rays, the small ion densities (n± ) and the aerosols. The various recombination coefficients for the loss of oppositely charged small ions (a i), oppositely charged aerosol ions (a a), between small ions and aerosol ions (a s), and the attachment of small ions of similar polarities with aerosols (b ) are used to compute the polar conductivity. The temperature, pressure, relative humidity, ionization rate and aerosol number density along with the different attachment/recombination coefficients are the input parameters for the SIAM. Diurnal values of conductivity computed on this model are compared with the experimentally determined values. A Gerdien condenser has been fabricated and used for the measurements. Good agreement between the model and the experimental conductivities values are seen. |
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Variations of large ions concentration in the air above Athens |
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D. Retalis P. Nastos A. Retalis |
| Large ions (positive and negative) concentration of air was regularly monitored at the NOA (National Observatory of Athens) atmospheric electricity station (66;=37°58' N, 55;=23°43'E, h=107m) for a long period from 1969-1980. At the Laboratory of Climatology (66;=37°58' N, 55;=23°47' E, h=243m), University of Athens, Panepistimioupolis, measurements of large ions concentration has been performed regularly since June 2002. The instruments used are of the same type as those used for the NOA recordings. At both stations, measurements of meteorological parameters (temperature, pressure, humidity, etc.) are performed on a daily basis. In this study the new recordings of the large ions concentration performed at Laboratory of Climatology are presented (which will be extended till time for the extended abstracts comes). The variations of the large ions concentration, the diurnal course, and the range of measurements are presented and compared with the relative recordings performed at NOA station for each month. The effect of meteorological parameters is also examined along with the particulate air pollution. The preliminary results form the study of the variation of the large ions concentration at both stations showed that:
Additionally, this paper will present an attempt to find a way for the connection of the long term measurements of large ions concentration performed at NOA station with the new recordings performed at Panepistimioupolis station, trying to find an ideal way for the development of a new database that will be further extended. References: Retalis D., Study of large ions concentration in the air above Athens. Arch. Met. Geoph. Biocl., Ser. A, 32, 1983. Retalis D., Pitta A., and Psallidas P., The conductivity of the air and other electrical parameters in relation to meteorological elements and air pollution in Athens. Meteor. Atmos. Phys., 46, 197-204, 1991. Retalis D. and A. Retalis, Effects of air pollution and wind on the large-ion concentration in the air above Athens, J. Geophys. Res., 103, 13,927-13,932, 1998. |
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The evolution of large ion stream in atmospheric boundary layer |
| V.V. Smirnov and A.V. Savchenko |
| The purpose of experiment is to estimate a character of electric field perturbations in an atmosphere after large ions injection. For ion production the water or diesel fuel droplets were introduced into a hot propulsion jet. Within condensation zone the corona discharge grid was installed. A vapor condenses on negative small ions and droplets are shaped by a diameter about 0.1 µm carrying one elementary charge. The effective current of large ions reached about I = 100 µA. The measurement data for vertical component of electric field E (X) under a jet by length up to 10 km are submitted in Fig.1. As it may be seen, the field gradient was reduced monotonically from E= -1000 V/cm up to E = -1.5 V/cm on distance 6 km. Experiment results we shall compare to calculation on numerical [1] and analytical [2] models. From calculations it follows that the charge neutralization of jet by background air ions (mean mobility µ+ = 1.4 .10-4 m2/V.s and concentration n+ = 109 m-3 ) should be account for distance X > 1 km. At X> 5 km the contribution of effect should exceed of turbulent diffusion contribution. By the test data on the figure this factor was exhibited more weakly. As it is visible, the simple analytical relation E (X) » 1\3p e 0X u*, where u* = 0.4 m/s is the dynamical wind speed, describes the experiment more exactly.
Measurements of polar electrical conductivities l and the space charge densities r have shown that on distances not less than 100 m from jet axis the l values were equal zero, but the density r have decreased only twice. The last can be the indicator that in a ion jet neighborhood there is a redistribution of space charge spectrum from small ions to large ions with the formation of a zone exhausted with charges. References:
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Ultrafine nucleus in ionized air |
| Vladimir V. Smirnov Jyrki M. Mäkelä |
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During of the International experiment HYYTIALA-2000, March-April 2000, Southern Finland (Mäkelä et al., 2000) convincing data were received on existing a interlink between moments of intensive generations of ultrafine particles D » 2 - 5 nm and atmospheric ions of intermediate mobility (0.5 - 0.05 cm2/V s). These regularities give an essential contribution to the acknowledgement of hypothesis on formation neutral particles after collisions of positive and negative small ions (Mäkelä, 1992; Smirnov, 1992; Turco et al., 1998). Correspond empirical model was accepted in different laboratory (Mäkelä and Kulmala, 1988; Smirnov and Savchenko, 1991; Smirnov, 1993) and natural experiments in the accident area of Chernobyl nuclear power station (Smirnov, 1991; Smirnov and Savchenko, 1996)). Experiment HYYTIALA-2000 has allowed observing an intensive formation of charged and neutral clusters in boundary layer of atmosphere. Proposed phenomenological model expects existence of Coulomb' associations of negative and positive small ions to form the neutral clusters of nitric or/and sulphate acid molecules M- (H2O)m + H3O+(H2O)m, where SOx or NOx. Characteristic time of neutral cluster formation is t nc = (n . 47;nc)-1/2 = 104 s, where the coagulation constant 47;nc = 5. 10-10 cm3 s-1, calculated on model of McMurry, 1983. In free troposphere the top limit concentration of neutral clusters is near Nnc ~ (n /47;nc )1/2 = 2.105 cm-3, mean diameter is Dnc » 1.3 - 1.5 nm. Association of small ions with neutral clusters transforms the previous into charged cluster or intermediate ions. Characteristic time of process is t cc ~ (b nc Nnc)-1 = 2.104 ± 2.103 s, b nc = p Cli D2nc /4 = 5. 10-10 cm3 s-1, where Cli » 3.104 cm/s is mean heat speed of small ions. Mean diameter of charge cluster is Dcc » 2 - 2.3 nm. Main channel of a sink for intermediate ions is Coulomb' associations between itself and with small ions. Top estimation of concentration for charged clusters possible get by means of formulas Ncc ~ (nli / 45;cc t cc )1/2 = 400 ± 100 cm-3. Here 45;cc = (2-4).10-7 cm3 s-1 is recombination constant. Below on fig.1 are given a satisfactory comparison of calculation and measurement data for small and intermediate ion concentration.
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Method of Inclined Velocities in the Air Ion Mobility Analysis |
| Hannes Tammet |
| Measurement of air ion mobility distribution is a key for understanding of the role of ion-induced nucleation in the atmosphere. Traditional measurement methods are drift tube of time-of-flight method and method of transversal velocities using aspiration condensers. An alternative "method of parallel velocities" proposed by Zeleny (1898) is forgotten today. Drift tubes are popular in high-resolution laboratory measurements; they make available Brownian limit of mobility resolution d = do = Ö (2kT/(qV)). The resolution of an aspiration condenser is worse, d = kdo, k > 1, and the resolution of the Zeleny instrument is better, k < 1. Aspiration condenser is still preferred in atmospheric measurements in spite its Brownian limit of resolution is low. Loscertales (1998) introduced the "method of inclined velocities" that composes high resolution (k < 1) with advantages of aspiration condenser. The problem is technical realization. Non-equipotential electrodes proposed by Loscertales encounter technological difficulties. A realistic way to accomplish the inclined field is the method of inclined grids. In the present report two variants of Inclined Grid Mobility Analyzer (IGMA) are discussed. Plain IGMA is good to keep the homogeneous plug air flow and homogeneous electric field. The mobility resolution can be several times better than of an equal voltage drift tube. Plain IGMA fits well the requirements for analytical laboratory instruments. When considering the atmospheric applications, the configuration of the instrument could be changed with an aim to collect more ions and achieve bigger electrometric signal. Electric field in a modified analyzer is not plain and should be calculated as a numerical solution of the Laplace equation. Design and experiments with an IGMA for atmospheric measurements are described in the report.
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| Last Update : June 3,
2003 |
Full program for Wednesday
Full
program for G2 Session
