ABSTRACT The use of Global Navigation Satellite System (GNSS) for air and terrestrial navigation and for many applications is increasing in the last decades. However, the Earth’s ionosphere causes GNSS signal delay due to the total electron content (TEC) and scintillation in the signal phase and amplitude. This scintillation can give rise to deleterious effects in the GNSS positioning. So, it is important to assess the effects of the ionosphere over the GNSS signal. To achieve this goal, it is necessary to have a large spatial and temporal coverage of data from many different sounders, being the GNSS receivers of great importance due to their global coverage and availability. In this work, we present a retrospective of the scintillation monitoring networks in Brazil and their characteristics. As the RBMC network managed by the IBGE provides TEC and as rate of TEC index (ROTI) is well correlated with ionospheric irregularities, we present also the RBMC network description. These RBMC GNSS receivers provide data in regions with scarcity of scintillation monitors. The description of the Ionospheric Scintillation Monitoring Receivers (ISMR) Query Tool, that is a web software that has been supporting research on the ISMR data, is also presented. (GNSS decades However Earths Earth s (TEC amplitude positioning So goal sounders availability work characteristics ROTI (ROTI irregularities monitors (ISMR Tool presented

ABSTRACT Air navigation is increasingly dependent on the use of Global Navigation Satellite Systems (GNSS). It allows the determination of the aircraft’s position in all phases of the flight and brings many advantages. Although GNSS navigation results in gains, the radio signals from these systems are strongly influenced by the ionospheric environment. It introduces errors that can affect the accuracy, integrity, availability and continuity requirements established by the International Civil Aviation Organization (ICAO). The ionospheric layer has different behaviors depending on the latitude, time of day, season of the year, geomagnetic activity and solar cycle. Since Brazil is located in a region of low latitudes, it experiences a series of unique challenges when compared to regions of mid-latitudes. For this reason, the application of GNSS-based technologies in aviation over the Brazilian territory requires an in-depth assessment of the ionosphere effects. Therefore, the Instituto Nacional de Ciência e Tecnologia (INCT) named GNSS Technology for Supporting Air Navigation was formed in 2017 to better assess the ionosphere impacts and assist government agencies and companies in the development of safe air navigation procedures over Brazil in a near future. This paper presents the most relevant advances achieved so far within this multidisciplinary project that involves Brazilian research centers and universities.

Os efeitos de duas tempestades magnéticas intensas sobre irregularidades ionosféricas foram analisados usando dados de cintilação do sinal de GPS das estações São Luís (2,57ºS, 44,21ºW, inclinação magnética 1,73ºS) na região equatorial, São José dos Campos (23,07ºS, 45,86ºW, inclinação magnética 18,01ºS) e Cachoeira Paulista (22,57ºS, 45,07ºW, inclinação magnética 18,12ºS) ambas sob a Anomalia da Ionização Equatorial (AIE) e São Martinho da Serra (29,28ºS, 53,82ºW, inclinação magnética 18,57ºS), localizada no sul do Brasil. Dados de CET (Conteúdo Eletrônico Total) também foram analisados. As tempestades analisadas ocorreram em 28-31 de outubro de 2003 e em 7-11 de novembro de 2004. Ambos períodos de tempestades apresentaram duas fases principais. Nas noites de 29/30 e 30/31 de outubro, durante as duas fases principais da tempestade, foi observado que o CET em São José dos Campos alcançou valores mais altos que do dia 10 de outubro que foi magneticamente calmo, devido ao efeito de penetração instantânea ao equador magnético de campo elétrico dirigido para leste e intensificando a AIE. Comparada a um dia calmo (10 de outubro), a cintilação na amplitude do sinal de GPS devido à irregularidade ionosférica, representada pelo índice de cintilação S4, foi mais forte em Cachoeira Paulista (sob a AIE) durante a noite de 30/31 mas não para a noite 29/30 e em São Martinho da Serra, durante as noites 29/30 e 30/31. A cintilação para as noites 29/30 e 30/31 nestas duas estações tiveram maior duração do que para a noite de 10 de outubro, alcançando o setor das horas após meia noite. Durante a tempestade de 7-11 de novembro, o CET teve o comportamento de um dia calmo, exceto durante os dias 10 e 11 (até 09 UT), quando uma diminuição significativa de CET foi observada. A cintilação, comparada ao dia 19 de novembro que foi calmo, foi maior na estação equatorial de São Luís durante as noites de 7/8 e 8/9 e foi completamente inibida para as estações de São Luís e São José dos Campos durante as noites 9/10 e 10/11, provavelmente devido à ação da penetração ao equador de campo elétrico do dínamo perturbado dirigido para oeste.

The effects of two intense magnetic storms over ionospheric irregularities were analyzed using GPS signal scintillation data from the stations of São Luís (2.57ºS, 44.21ºW, dip latitude 1.73ºS) in the equatorial region, São José dos Campos (23.07ºS, 45.86ºW, dip latitude 18.01ºS) and Cachoeira Paulista (22.57ºS, 45.07ºW, dip latitude 18.12ºS) both under the Equatorial Ionization Anomaly (EIA), and São Martinho da Serra (29.28ºS, 53.82ºW, dip latitude 18.57ºS), located in the South of Brazil. Total Electron Content (TEC) data for São Luís and São José dos Campos, were also analyzed. The analyzed storms occurred on October 28-31, 2003 and on November 7-11, 2004. Both storm periods presented two main phases. In the nights of 29/30 and 30/31 of October, during the two storm main phase, it was observed that TEC over São José dos Campos reached higher values than the TEC for the magnetically quiet day of October 10, due to the effect of eastward electric field prompt penetration to magnetic equator that intensified the EIA. Compared to a quiet day (Oct 10), scintillation in the GPS signal amplitude due to ionospheric irregularity, quantified by the scintillation index S4, was stronger for Cachoeira Paulista (under EIA) during the night of 30/31but not for the night of 29/30 and for São Martinho da Serra was stronger during the nights of 29/30 and 30/31. Scintillation for the nights of 29/30 and 30/31 at these two stations lasted longer than on October 10, reaching the post midnight time sector. During the November 7-11 storm, TEC kept the behavior of a quiet day except during days 10 and 11 (up to 9 UT), when a large TEC decrease was observed. The GPS scintillation, compared to the quiet day November 19, was larger at the equatorial station of São Luís during the nights of 7/8 and 8/9 and it was completely inhibited for the São Luís and São José dos Campos stations during the nights of 9/10 and 10/11, probably due to action of westward disturbance dynamo electric field penetration to equator.