Abstract
The objective of the present proposal is to acquire, install and carry out observations during the coming years using three GPS (Global Positioning System) receivers in the Brazilian equatorial and low latitude regions, co-located with digital ionosonde and multi-channel all-sky imaging system at CEULP, Palmas, TO, and with multi-channel all-sky imaging system at LNA, Brazópolis, MG. We have a GPS receiver in routine operation at UNIVAP, S.J.Campos, SP, with digital ionosonde and multi-channel all-sky imaging system. At Manaus, AM, with a digital ionosonde, we have a GPS receiver operational in the RBMC (IBGE) network. One GPS receiver we would like to have located at Ji-Paraná, RO, a location in the extreme west region of Brazil (close the magnetic equator). The realization of these joint observations from different locations utilizing different instruments and techniques (optical and radio-frequency), aims to obtain set of observational data to study the different aspects of ionospheric behavior, particularly related to geomagnetic storms, day-to-day and long-term variations (mainly related to the 11-year solar cycle), as evident from the total electron content, generation and dynamics of the ionospheric irregularities and the Solar-Terrestrial relationship (solar wind/magnetosphere/ionosphere/thermosphere). It should be mentioned that there has been great advancements in the studies related to the interactions between the disturbed magnetosphere and ionosphere/thermosphere at high latitudes during the recent decades, however, this phenomenon is much less studied in the equatorial and low latitude regions. Considering that Brazil has a continental dimension and most of the part of its territory is localized in these regions, it is expected that the proposed observations and studies will be of great importance to understand topics related to Space Physics. Other topics which will receive major attention for investigations are those related to the equatorial ionospheric irregularities and large-scale ionospheric plasma depletions (transequatorial plasma depletions) generated by the Rayleigh-Taylor gravitational instability process. These ionospheric irregularities in the F-region (equatorial spread-F (ESF)) are ionospheric electron density fluctuations or structures varying from a few centimeters (small-scale) to several hundred kilometers (large-scale). Considering the variable characteristics of the ionospheric irregularities, the proposed studies assume great importance in the area of ionospheric radio wave propagation utilized in large scale for communication and navigation purposes in Brazil. The duration proposed for the acquisition, installation and for publications resulting from the studies related to this project is two years. (AU)