Tomografia da ionosfera a partir do GNSS e técnicas algébricas: estudo de caso para a região brasileira

• Ano de defesa: 2015
• Autor(a) principal: Prol, Fabricio dos Santos [UNESP]
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Estadual Paulista (Unesp)
• Palavras-chave em Português: Cartografia; Geomática; Ionosfera; Sistemas de navegação global por satélite; Cartography
• Link de acesso: http://hdl.handle.net/11449/123727; http://www.athena.biblioteca.unesp.br/exlibris/bd/cathedra/02-06-2015/000831761.pdf

The spatial and temporal variations of the electron density in the atmosphere make the ionosphere a difficult region to model. A major difficulty arises from the incomplete geometrical coverage of the Global Navigation Satellite System (GNSS) for tomographic applications, turning the ionospheric tomography system into an ill-conditioned equation system. Although the tomography system is ill-conditioned, several techniques were developed to partially overcome the problem. There is great interest in using the tomographic techniques for ionospheric imaging, because it allows describing the ionosphere in terms of electron density, which is an important parameter to study the behavior of physical and chemical processes that occur on the upper atmosphere and for the correction of the ionospheric delay in the GNSS positioning. In Brazil, there are additional interests in tomographic techniques, due to the peculiar characteristics of the ionosphere and of the geomagnetic field over the region. In this direction, methods for ionospheric tomography reconstruction are presented and discussed in this work. Particular emphasis is given to the mathematical formulation from grid-based (or algebraic techniques) and function-based methods and some of their main advantages and limitations are presented. An application was performed using the grid-based methods in the Brazilian sector...