Navegando por Assunto "Geomagnetic storms"

Agora exibindo 1 - 3 de 3
  • Imagem de Miniatura
    Item
    Analysis of Y-component of geomagnetic field and SYM-H Index using wavelet multiresolution analysis
    (Springer Nature Link) Sapkota, Santosh; Saurav, Sarup Khadka; Gautam, Sabin; Karki, Monika; Adhikari, Binod; Mishra, Roshan Kumar; Oliveira, Virgínia Klausner de; Dhungana, Beni Madhav
    Electrodynamical coupling between the solar wind’s plasma and the Earth’s magnetosphere cre- ates geomagnetic disturbances recorded on the ground. This work analyzes the Y-component of the geomag- netic field during two geomagnetic storms and compares it to the solar quiet days. The magnetogram data recorded on low latitude stations are used for the study. We investigated the correlation of the Y-component with geomagnetic index SYM-H using wavelet multiresolution analysis. We have used solar wind velocity, pressure, and interplanetary magnetic fields (By and Bz) to know the interplanetary structure for the selected duration. We found a positive correlation between Y-component and the SYM-H index for both events. The magnitude of the Y-component was significantly reduced during the main phase in comparison to the quiet days. Further, variation of solar wind parameters indicated geomagnetic storms are guided by the prolonged southward IMF-Bz component and highly fluctuated IMF-By component. This work connects the inter- planetary plasma parameters to the storm-time geomagnetic variations.
  • Imagem de Miniatura
    Item
    Lithosphere atmosphere ionosphere coupling during the September 2015 Coquimbo earthquake
    (Springer Nature Link) Adhikari, Bhoj Raj; Klausner, Virgínia; Cândido, Claudia Maria Nicoli; Poudel, Prakash; Macedo, Humberto Gimenes; Silwal, Ashok; Gautam, Sujan Prasad; Calabia, Andrés; Shah, Munawar
    This study explores temporal variations in seismic data, interplanetary parameters, and geomagnetic indices during the 2015 Coquimbo earthquake. We employ wavelet transform techniques to investigate potential coupling mechanisms between the lithosphere, atmosphere, and ionosphere (LAI), even during geomagnetically disturbed periods. Our analysis is strengthened by evaluating geomagnetic data and all- sky images within a 2000–3000 km radius of the epicenter. We explore the post-Chilean earthquake seismogenic perturbations in the upper atmosphere on September 16–17, 2015. Coseismic and post- seismic events emerge in the Brazilian region 1–3 hrs after the earthquake onset. The co-occurrence and subsequent response of these disturbances to seismic events suggest their seismogenic nature. Addi- tionally, we utilize geomagnetic storm and interplanetary magnetic Beld (IMF) indices to differentiate magnetic Cuctuations arising from solar storms during seismic events. While our study detects magnetic disturbances associated with seismic activity, distinguishing them from the eAects of solar storms in the geomagnetic records or all-sky images remains challenging. These observations prompt further investigation into the intricate interplay between geomagnetic and ionospheric disturbances and their connection to seismic and geomagnetic storm activity.
  • Imagem de Miniatura
    Item
    Statistical analysis on the ionospheric response over South American mid- and near high-latitudes during 70 intense geomagnetic storms occurred in the period of two decades
    (Elsevier) Abreu, Alessandro José de; Correia, Emilia; Jesus, Rodolfo de; Venkatesh, Kavutarapu; Macho, Eduardo Perez; Roberto, Marisa; Fagundes, Paulo Roberto; Gende, Maurício Alfredo
    The first-time statistical response of the positive and negative ionospheric storms phases using Vertical Total Electron Content (VTEC) measurements during 70 geomagnetic storms at near high- and mid-latitudes regions in the Antarctic and Argentine/Chilean sectors in the Southern hemisphere are investigated. The study covers the years between 1999 and 2018 of solar cycles 23 and 24, using the Dst ≤ −100 nT as a criterion for all 70 storms selected. Significant features of solar cycle, seasonal and local time of ionospheric storms are showed. Our results indicate that the occurrence of geomagnetic storms follows a pattern of solar activity dependence, and also indicate a predominance of positive and positive-negative phases during autumn, winter, and spring at mid-latitudes and winter at near high-latitudes. Negative and negative-positive phases occur during all seasons at near high- and mid-latitudes. In addition, positive phases occur more frequently during the daytime while the negative phases occur predominantly in nighttime. There is also a predominance of positive and positive-negative phases simultaneously at near high- and mid-latitudes in the Antarctic and Argentine/Chilean sectors. The percentages of occurrence of positive and positive-negative phases are of 50% and 19%, respectively, at mid-latitude and 60% and 22%, respectively, at near high-latitudes. Negative and negative-positive phases are below 9% at both latitudes.