@MastersThesis{Oliveira:2021:CrMaFi,
author = "de Oliveira, Isabela",
title = "Crustal magnetic field advection on Mars by ionospheric plasma
flow",
school = "Instituto Nacional de Pesquisas Espaciais (INPE)",
year = "2021",
address = "S{\~a}o Jos{\'e} dos Campos",
month = "2020-08-25",
keywords = "Mars atmosphere, planetary ionospheres, planetary magnetic fields,
remanent magnetization, advection, atmosfera de Marte, ionosferas
planet{\'a}rias, campos magn{\'e}ticos planet{\'a}rios,
magnetiza{\c{c}}{\~a}o remanescente, advec{\c{c}}{\~a}o.",
abstract = "The planet Mars has unique magnetic features among the solar
system bodies. Although the planet does not currently have an
active dynamo that generates a global magnetic field, like Earth
has, there are regions in its crust which are strongly magnetized.
Some of these magnetic fields have magnitudes comparable to
magnetic fields on Earth. Evidences suggest that the crustal
magnetic fields on Mars are remanent signatures from a Martian
dynamo that was active in the past. These strongly magnetized
regions, above which mini-magnetospheres are formed, are what
distinguishes Mars from the other planets of the Solar System.
Like at Venus, the interactions between the solar wind and Mars
are mostly dominated by the properties of its ionosphere. However,
Mars mini-magnetospheres influence the ionospheric interactions,
changing ionospheric parameters and disturbing or generating local
and global ionospheric currents. In this work, we propose that the
crustal magnetic fields of Mars not only interfere in the planets
ionosphere, but that also the contrary can happen, i.e., the
ionosphere can disturb the crustal magnetic fields. We
specifically study whether the ionospheric flow is able to
displace the crustal magnetic fields by advection, dragging them
in the anti-solar direction, along the day-to-night flow of the
ionospheric plasma. In order to identify advection of the magnetic
fields on Mars, we perform statistical analyses using data from
MAVEN and MGS spacecraft over long periods of time. MAVEN radial
magnetic field data of the whole planet are selected for the
dawn-side and the dusk-side of Mars and compared to a crustal
magnetic field model, for altitude ranges between 200-1000 km. The
results show evidences that the magnetic fields are displaced and
the cause for the displacement is likely to be advection due to
the ionospheric flow. We also use MGS radial magnetic field data
to investigate the advection on small regions of the planet and
with a higher spatial resolution. We compare day-side data to
night-side data at the orbit altitude of 400 km. The displacement
of the magnetic fields seems to be correlated to the distance from
the magnetic field to the main patch of magnetization in the
Southern hemisphere of the planet. In order to have a general idea
of the forces involved in the advection of the magnetic fields, we
compare the dynamic pressure of the ionospheric plasma flow to the
magnetic pressure of the crustal magnetic fields. For this study,
we use MAVEN magnetic field and ionospheric data between 200-1000
km and between 04:00-20:00 local times. The results indicate that
the advection of the magnetic fields is likely to be more
expressive at the terminator regions of the planet, above regions
of weak magnetic field background, e.g., in the Northern
hemisphere of Mars. RESUMO: O planeta Marte tem
caracter{\'{\i}}sticas magn{\'e}ticas {\'u}nicas dentre os
corpos do sistema solar. Embora o planeta atualmente n{\~a}o
tenha um d{\'{\i}}namo ativo que gere um campo magn{\'e}tico
global, como o da Terra, existem regi{\~o}es fortemente
magnetizadas em sua crosta. Alguns desses campos magn{\'e}ticos
t{\^e}m magnitudes compar{\'a}veis aos campos magn{\'e}ticos da
Terra. Evid{\^e}ncias sugerem que os campos magn{\'e}ticos
crustais de Marte s{\~a}o assinaturas remanescentes de um
d{\'{\i}}namo marciano que esteve ativo no passado. Essas
regi{\~o}es fortemente magnetizadas, acima das quais
minimagnetosferas s{\~a}o formadas, s{\~a}o o que distingue
Marte dos outros planetas do Sistema Solar. Como em V{\^e}nus, as
intera{\c{c}}{\~o}es entre o vento solar e Marte s{\~a}o
predominantemente dominadas pelas propriedades de sua ionosfera.
Contudo, minimagnetosferas de Marte influenciam as
intera{\c{c}}{\~o}es ionosf{\'e}ricas, alterando os
par{\^a}metros ionosf{\'e}ricos e perturbando ou gerando
correntes ionosf{\'e}ricas locais e globais. Neste trabalho,
propomos que os campos magn{\'e}ticos crustais de Marte n{\~a}o
apenas interferem na ionosfera do planeta, mas que tamb{\'e}m o
contr{\'a}rio pode acontecer, ou seja, a ionosfera pode perturbar
os campos magn{\'e}ticos crustais. Estudamos especificamente se o
fluxo ionosf{\'e}rico {\'e} capaz de deslocar os campos
magn{\'e}ticos da crosta por advec{\c{c}}{\~a}o, arrastando-os
na dire{\c{c}}{\~a}o anti-solar, ao longo do fluxo di{\'a}rio
do plasma ionosf{\'e}rico. Para identificar a
advec{\c{c}}{\~a}o dos campos magn{\'e}ticos de Marte,
realizamos an{\'a}lises estat{\'{\i}}sticas usando os dados das
espa{\c{c}}onaves MAVEN e MGS por longos per{\'{\i}}odos de
tempo. Os dados da componente radial do campo magn{\'e}tico da
MAVEN de todo o planeta s{\~a}o selecionados para o lado do
amanhecer e do crep{\'u}sculo de Marte e comparados com um modelo
de campo magn{\'e}tico crustal, para faixas de altitude entre
200-1000 km. Os resultados mostram evid{\^e}ncias de que os
campos magn{\'e}ticos est{\~a}o deslocados e a causa do
deslocamento provavelmente {\'e} a advec{\c{c}}{\~a}o devido ao
fluxo ionosf{\'e}rico. Tamb{\'e}m usamos dados da componente
radial do campo magn{\'e}tico da MGS para investigar a
advec{\c{c}}{\~a}o em pequenas regi{\~o}es do planeta e com uma
resolu{\c{c}}{\~a}o espacial mais alta. Comparamos os dados
diurnos com os noturnos na altitude da {\'o}rbita de 400 km. O
deslocamento dos campos magn{\'e}ticos parece estar
correlacionado {\`a} dist{\^a}ncia do campo magn{\'e}tico ao
principal bloco de magnetiza{\c{c}}{\~a}o no hemisf{\'e}rio Sul
do planeta. Para ter uma id{\'e}ia geral das for{\c{c}}as
envolvidas na advec{\c{c}}{\~a}o dos campos magn{\'e}ticos,
comparamos a press{\~a}o din{\^a}mica do fluxo de plasma
ionosf{\'e}rico com a press{\~a}o magn{\'e}tica dos campos
magn{\'e}ticos crustais. Para este estudo, usamos dados da MAVEN
do campo magn{\'e}tico e da ionosfera entre 200-1000 km e entre
04:00-20:00 do hor{\'a}rio local. Os resultados indicam que a
advec{\c{c}}{\~a}o dos campos magn{\'e}ticos {\'e}
provavelmente mais expressiva nas regi{\~o}es do terminadouro do
planeta, acima das regi{\~o}es de fraco campo magn{\'e}tico de
fundo, e.g., no hemisf{\'e}rio Norte de Marte.",
committee = "Wrasse, Cristiano Max (presidente) and Echer, Ezequiel
(orientador) and Franco, Adriane Marques de Souza (orientadora)
and Fr{\"a}nz, Wolfram Johannes Markus (orientador) and Dal Lago,
Alisson and Guedes, F{\'a}bio Becker and Marques, Manilo Soares",
englishtitle = "Advec{\c{c}}{\~a}o do campo magn{\'e}tico crustal em Marte pelo
fluxo ionosf{\'e}rico de plasma",
language = "en",
pages = "89",
ibi = "8JMKD3MGP3W34R/433F7E8",
url = "http://urlib.net/ibi/8JMKD3MGP3W34R/433F7E8",
targetfile = "publicacao.pdf",
urlaccessdate = "03 maio 2024"
}