Studies of the interactive processes of the equatorial ionosphere-thermosphere system

Abstract

This research proposal seeks to investigate the interactive/coupling processes of the equatorial ionosphere-thermosphere system (EITS) that constitutes a fundamental component of our space environment, and covers a major part of the brazilian territory both north and south of the magnetic equator. The basic interactive process consists in the wind system of the upper atmosphere and the magnetized conducting layers of the ionosphere producing the dynamoelectric fields of the ionospheric E and F-layers. These electric fields, together with their driving winds, and waves, are responsible for the major phenomena of the EITS: the equatorial electrojet current system and the associated plasma instability processes; the anomalies in electron density, wind and temperature distributions; and the plasma bubbles and associated irregularities. These phenomena are also controlled, in thebrazilian region, by the South Atlantic Magnetic Anomaly (SAMA). The interactive processes are such that a study of one of these phenomena requires detailed knowledge of the other phenomena as well. The equatorial ionosphere has significant influences over a number of space application activities. The equatorial ionization anomaly and the plasma bubbles control the ionospheric, trans-ionospheric and space communication links, global positioning system satellite applications, space geodesy, over-the-horizon radar operations, space shuttle based radar remote sensing etc. The investigations proposed here will focus on the ambient conditions of the EITS that control the generation, growth and decay of the major EITS phenomena. Specific attention will be given to the causes of the day to day variability in the occurrence of plasma bubble irregularities that has direct impact on space application areas. Other/related points of specific focus will include: the relative importance of electric fields and winds in the generation and growth of the major phenomena; instability mechanisms responsible for the plasma bubble processes; response of the EITS to forcing from the magnetosphere, and to disturbances from lower atmosphere through gravity- and planetary-waves; and the effect of SAMA in the electrodynamics of the EITS. Experimental data on the EITS will be collected in routine and campaign mode operations of diverse ground-based radio and optical devices located at the equatorial and low latitude sites, São Luis, Fortaleza and Cachoeira Paulista, in Brazil... (AU)