Physics of auroral phenomena : proceedings of the 33rd Annual seminar, Apatity, 02 - 05 March, 2010 / [ed.: A.G. Yahnin, A. A. Mochalov]. - Апатиты : Издательство Кольского научного центра РАН, 2011. - 206 с. : ил.

A.A. Kruglov al al. (p{r,e,< t> )=Y,Yj /=0 j=~i ,PM-R) _ e M rr R) ■Yvm ) а л ] а 2 + 4 j u / R 2 P\ ~ ~ ~ Z + а л ] а 2 + 4 j u / R 2 ( 6 ) 2 4 // If a » —— the solution of (6) can be simplified: R 1 <P(r, в,Ф) =---- .в-Ф) l - e 1 expression (7) From the (7) follows that if a( t] —R ) » l(r( — R « 6 0 /ш ) the expression for the radial (vertical) component of the electric field will be: dcp ( 8 ) (9) Е г = - ^ = - а е - а1г-«)<р(г1,в ,ф ) or For r = R we will get: 8 min(/,3) _ E,(r = *) = - « £ £ Сиы е ,ф ) =-а<р{гх,6,<1 /=0 7=0 where: I'. (6», ф) = (cos 6>)cos ]ф + (cos в ) sin , Р / (cos в ) - associated Legendre functions. From the expression (9) we can see that the electric field near the Earth's surface is proportional to the potential o f the electric field in the ionosphere. Believing that the potential of the ionosphere (Ф,) can be presented as = ^sw + Фо, where Ф5„ - Weimer -model potential and Ф0, - potential created by thunderstorms, we can rewrite the equation (1) as Ez = ETH+ a®sw (10) If we have the measured electric field (Ez), the calculated Weimer-model ionospheric potential (Ф5„) the simple linear regression analysis can give us the thunderstorm part of the electric field (Ezt) and a - the value proportional to the conductivity o f the atmosphere. The analysis o f experimental data The results of linear regression analysis are shown in fig-1- Fig.l represents the diurnal variations of the thunderstorm part of measured electric field for each month of 4 years (1998-2001). The average diurnal curves for Antarctic summer and winter are shown in fig.2. The classical Carnegie curve (Chalmers 1967) is shown on the right panel. One can see very good agreement of Antarctic summer (north hemisphere winter) curves with Carnegie curve. Daily curves of ETH for each month were deducted from the hourly average values of the measured field in order to gain a part of the solar-wind-imposed variations (Esw). Diumal course of correlation (R)) coefficients between ETH and Osw for 1998-2001 are presented in fig.3. One can see positive correlation for all time intervals with a maximum in the geomagnetic morning (03 - 09 UT) and day hours (09 - 18 UT) (for Vostok 00 MLT=01 UT) Fig. 1. Diumal curves o f the thunderstorm part of atmospheric electric field measured at Vostok st. for every month of 1998-2001. Fig. 2. Daily curves of thunderstorms part o f the atmospheric electric field for Antarctic summer and winter (left panel) and Carnegie curve (right panel). 172