Location of large scale reconnection at Earth's dayside magnetopause as probed by analytical X-line models and in situ observations

• Ano de defesa: 2015
• Autor(a) principal: Vitor Moura Cardoso e Silva Souza
• Orientador(a): Daiki Koga, Odim Mendes Junior
• Banca de defesa: Renato Sérgio Dallaqua, David Gary Sibeck, Flávia Reis Cardoso
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Instituto Nacional de Pesquisas Espaciais (INPE)
• Programa de Pós-Graduação: Programa de Pós-Graduação do INPE em Geofísica Espacial/Ciências do Ambiente Solar-Terrestre
• País: BR
• Link de acesso: http://urlib.net/sid.inpe.br/mtc-m21b/2015/02.27.16.38

The magnetic reconnection process is believed to occur throughout the Universe whenever distinct magnetized plasma regimes come together and interact. It has also been shown to be the dominant process for the solar wind-magnetosphere interaction. In this work the large scale aspect of the magnetic field reconnection process is investigated: where does reconnection occur along the Earth${'}$s dayside magnetopause and what are the key parameters governing its location? We perform an intercomparison of three analytical model${'}$s, which predict the reconnection X-line location and orientation, namely Trattner et al. (2007), Gonzalez and Mozer (1974), and Swisdak and Drake (2007) against two sets of reconnection events which are identified mostly by the in situ detection of accelerated plasma flows. In the first set, we show four fortuitous, quasi-simultaneous dayside magnetopause crossing events where two widely separated spacecraft detect reconnection signatures, and the possible X-line location can be inferred from the observations. The X-line models are then used and their predictions are compared with the expected X-line location obtained from observation. The results suggest that an extended (> 5 Earth radii in length), component-type reconnection X-line may in fact be a likely scenario at Earth${'}$s dayside magnetopause, connecting and structuring the reconnection characteristics on far apart observation points. In the second set of reconnection events, we have analyzed the X-line models performance in predicting the observed reconnection outflow direction, i.e., its north-south and/or east-west senses, in a total of 116 single magnetopause crossing events where reconnection-generated plasma flows were clearly present. We found that the Swisdak and Drake (2007)s X-line model had a slightly better performance in predicting both accelerated plasma flow components: north-south (72\% of the cases) and east-west (54\% of the cases), as compared to the Trattner et al. (2007) model (66\% north-south, 37\% east-west), and Gonzalez and Mozer (1974) model (60\% north-south, 42\% east-west). The Swisdak and Drake (2007) model takes into account the realistic asymmetrical magnetic fields and plasma density conditions across the magnetopause boundary layer, thus the result suggests that in addition to external boundary conditions such as the interplanetary magnetic field orientation and solar wind dynamic pressure value, the local plasma and magnetic field conditions play an important role in determining the large scale X-line orientation at Earth${'}$s dayside magnetopause, in particular the local plasma $\beta$, as it has been shown elsewhere (PHAN et al., 2013).