Climatology of the scintillation onset over southern Brazil

Jonas Sousasantos,Rafael S. Paolini,Eurico R. de Paula,José H. A. Sobral,Alison de Oliveira Moraes,Marcio T. A. H. Muella

doi:10.5194/angeo-36-565-2018

Abstract

Abstract. This work presents an analysis of the climatology of the onset time of ionospheric scintillations at low latitude over the southern Brazilian territory near the peak of the equatorial ionization anomaly (EIA). Data from L1 frequency GPS receiver located in Cachoeira Paulista (22.4∘ S, 45.0∘ W; dip latitude 16.9∘ S), from September 1998 to November 2014, covering a period between solar cycles 23 and 24, were used in the present analysis of the scintillation onset time. The results show that the start time of the ionospheric scintillation follows a pattern, starting about 40 min earlier, in the months of November and December, when compared to January and February. The analyses presented here show that such temporal behavior seems to be associated with the ionospheric prereversal vertical drift (PRVD) magnitude and time. The influence of solar activity in the percentage of GPS links affected is also addressed together with the respective ionospheric prereversal vertical drift behavior. Based on this climatological study a set of empirical equations is proposed to be used for a GNSS alert about the scintillation prediction. The identification of this kind of pattern may support GNSS applications for aviation and oil extraction maritime stations positioning. Keywords. Ionosphere (ionospheric irregularities; modeling and forecasting) – radio science (space and satellite communication)

Highlights

The ionospheric scintillations considered here consist of rapid time variations in the amplitude and phase of the satellite radio signal passing through the ionosphere
The density gradient, antiparallel to the gravity, usually becomes steeper, and this unstable configuration may lead to the generation of Rayleigh– Taylor instability (RTI) that implies the formation of large regions of density irregularities called equatorial plasma bubbles (EPBs)
This work presented and discussed the climatology of the scintillation onset over southern Brazil, in a station located in Cachoeira Paulista, a place under the southern crest of the equatorial ionization anomaly

Summary

Introduction

The ionospheric scintillations considered here consist of rapid time variations in the amplitude and phase of the satellite radio signal passing through the ionosphere. Since scintillation degrades navigation performance, the research of climatology, morphology and dynamics of irregularities (spanning from hundreds of meters to a few kilometers) for estimation and prediction of equatorial and low-latitude scintillation is a major concern in the radio science and space weather field The density gradient, antiparallel to the gravity, usually becomes steeper, and this unstable configuration may lead to the generation of Rayleigh– Taylor instability (RTI) that implies the formation of large regions of density irregularities called equatorial plasma bubbles (EPBs) These EPB structures are responsible for severe scintillation scenario and registers of EPB activities over the Brazilian region have been made since 1978 (Sobral et al, 1980).

Measurements and data processing

Scintillation onset pattern

Vertical drift and hmF2 as obtained from SAMI2 Model

Results and discussion

Conclusion