Exogenous particles in the upper atmosphere dynamics: Causes and consequences

DASSO S.

tucuman

Conferencia; XXVI Reunión Científica de la Asociación Argentina de Geofísicos y Geodestas (AAGG); 2012

The upper atmosphere mainly evolves as consequence of a hard battle happening in the transition from the neutral gas surrounding Earth to the fully ionized gas embedding the solar system. It is well known that the dynamics of the upper atmosphere significantly depends on heating from solar radiation, on production and loosing of ions and electrons (mainly from photo-ionization processes and energetic particle fluxes), and on the transference of kinetic energy from the solar wind to the magnetosphere through electro-dynamical mechanisms. The excitation of this last mechanism strongly depends on the solar wind conditions, and its efficiency usually can be quantified from using indexes of geomagnetic activity. The magnetosphere is exposed to different kind of charged particles: (1) majority thermal particles composing the interplanetary plasma, (2) minority suprathermal particles of solar origin, and (3) a few relativistic particles mostly of galactic origin (the so-called cosmic rays). The large variability of these particle fluxes, combined with the variability of the interplanetary magnetic conditions, determine the level of the external drivers and the consequent impact on the dynamics of the gas in the upper terrestrial environment. Under certain conditions, particles and magnetic field work together as catalysts, increasing the efficiency for transference of energy and momentum from the solar wind to the terrestrial plasmasphere. In this talk I will present an introduction to the some important physical processes and phenomena in these natural scenarios, as well as the state of the art on the solar-terrestrial relationship, showing results found during the last years on the main mechanisms controlling the Sun-Earth coupling during transient extreme events.