Manzano, J. R.

Coupling parameter, E, and the total energy dissipated by the magnetosphere, UT, are determined for six disturbed periods, following three known criteria for UT computation. It is observed that UT exceeds E for Dst < -90 nT, for alI models. Differences between models reside on the estimated valnes for the particles' life time il1 the equatorial ring current. The values of TR, used in the models, are small during the main phase of the di."turbance, in disagreement with the charge exchange life time of the majority species, H+ and O'-. Based on this conclusion, a different criterion to calculate TR is proposed, differentiating the different stages of the perturbation. TR is calculated, for the main phase of the storm, from the rate of energy deposition estimation, Q, in the ring current. For Dst recovery phase, the vallles are obtained from a ring current decay law computation. The UTvu calculated, physically more coherent with the processes occurring during the event, is now smaller than expected. In this sense, it is understood that the power generated by the solar wind-magnetosphere dy- namo, should also be distributed in the inner magnetosphere, auroral zones and equatorial ring current, as in the outer magnetosphere, plasmoids in the tail shot in antisolar direction. A further adjustment of E, with the Chapman-Ferraro distance, 10' variable, has been made. Although the reslllts, improve the estimation of E, they are sti!l smaller than UT, except UTNU, for some disturbed periods. This result indicates the uncertainty in the computation of the input energy, by using the many expressions proposed in the literature, which are always presented as laws proportional to a given group of parameters, with an unknown factor of proportionality, which deserves more detailed physical analysis.

Effects on the F region of two active meteorological systems will be analyzed. These systems are known as Mesoscale Convective Complexes (MCCs). Ionospheric data from a vertical sounder located in Tucumán will be used. By comparing the behaviour of the F region parameters on the days before and after the MCC storm day, we see outstanding differences. These differences occur during night and dawn hours in both cases. The two phenomena show influences on the F region. One case shows an increase in electronic concentration followed by a decrease and the other shows the opposite effect. Gravity wave propagation from the top of clouds could be connected to these MCCs effects. Other possible physical mechanisms are also discussed.

Neutral wind effects in the F2-region during geomagnetic storms are theoretically studied solving the continuity equation (with production and loss of electrons) by means of a numerical method. This study was made for storms with sudden commencement at different times of day and at different latitudes. The results show that the equatorward movements of neutral air produce either enhanced or depressed maximum electron density values which depend on the velocity of these winds when the perturbation occurs at diurnal hours. If the geomagnetic storm is present during the night, only enhanced values are observed.

Available magnetic records from eight stations in the Antarctica, for the March 1989 geomagnetic storm, are used to construct the southern hemisphere auroral indices, analogous to the boreal ones. The results show a diurnal variation depending on the distribution of the stations. An acceptable correlation between the northern and southern hemisphere indices are found except for the index indicating the presence of the eastward auroral electrojet. However, differences in the amplitudes of both auroral electrojet indices were observed.