Programa de Pós-Graduação em Física e Astronomia

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Navegando Programa de Pós-Graduação em Física e Astronomia por Autor "Andrioli, Vania Fatima"

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    New Findings of the Sporadic E (Es) Layer Development Around the Magnetic Equator During a High-Speed Solar (HSS) Wind Stream Event
    (Advancing Earth and Space Sciences) Resende, Laysa Cristina Araújo; Zhu, Y.; Denardini, Clezio Marcos; Batista, Inez Staciarini; Shi, Jiankui; Moro, Juliano; Chen, Sony Su; Santos, Fredson Conceição; Silva, Ligia Alves da; Andrioli, Vania Fatima; Muella, Marcio Tadeu de Assis Honorato; Fagundes, Paulo Roberto; Carrasco, Alexander Jose; Pillat, Valdir Gil; Wang, Chi; Liu, Z.
    The equatorial (Esq) and blanketing (Esb) sporadic (Es) layers occur due to the EquatorialElectrojet Current (EEJ) plasma instabilities and tidal wind components, respectively. Both Esq and Esb layers can appear concurrently over some Brazilian equatorial regions due to the peculiar geomagnetic field configuration in this sector. Previous works indicate that the inclination angle limit for the Esq occurrence in ionograms is 7°. However, we found evidence that regions more distant can also experience such equatorial dynamics during disturbed periods. In this context, we deeply investigated this EEJ influence expansion effect by analyzing the Esq layers in regions not so close to the magnetic equator during a high-speed solar wind stream event that occurred on May 05 and 06, 2018. To explain these atypical Esq layer occurrences, we considered the Es layer parameters obtained from digital ionosondes over the Brazilian regions, São Luís (dip: 9.5°), and Araguatins (dip: 10.5°). We use magnetometer data and a model named MIRE (E Region Ionospheric Model) to validate this mechanism. The results show that the eastward electric field of the Gradient Drift instability in the EEJ is effective during the magnetic storm main phase in the boundary equatorial magnetic sites, creating the Es q layers. Thus, the EEJ plasma irregularity superimposes the wind shear mechanism, changing the Es layer dynamics during disturbed periods over the magnetic equator boundary sites. Therefore, this work establishes new findings of the EEJ influence expansion dynamics in the Es layer formation over the Brazilian regions, which was considered in MIRE for the first time.
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    Possible relationship of meteor disintegration in the mesosphere and enhancement of sodium atoms: A case study on july 05, 2013
    (Elsevier) Pimenta, Alexandre Alvares; Batista, Paulo Prado; Andrioli, Vania Fatima; Fagundes, Paulo Roberto; Batista, Inez Staciarini
    Our observations show that on some occasions an influx of meteor ablation possibly contributes to appearance of a sudden enhancement in mesospheric sodium density. On July 05, 2013, all-sky images with a narrow sodium filter in the 589 nm emission, operating at Cachoeira Paulista (22.7 S, 45 W) and lidar observations of the mesospheric sodium layer, operating at Sa˜o Jose´ dos Campos (23.1 S, 45.9 W), both observatories in Brazil, show a possible relationship of meteor disintegration and appearance of sodium enhancements on the background layer. After the meteor impact, the all-sky images showed a sodium cloud that was seen for about 10 min through the images in the NaD 589 nm emission, with initial dimensions of approximately 36 km 9 km and initial speed of about 90 m/s southward. In addition, our observations show that the movement of sodium cloud in the horizontal plane around 90 km is relatively anisotropic and change the dimensions with time