Abstract. The Tatuoca magnetic observatory (IAGA code: TTB) is located on a small island in the Amazonian delta state of Pará, Brazil. Its location close to geomagnetic equator and within South Atlantic Anomaly offers high scientific return observatory's data. A joint effort by National Observatory Brazil (ON) GFZ German Research Centre for Geosciences (GFZ) was undertaken, starting from 2015 order modernise with goal joining INTERMAGNET network provide real-time data access. In this paper,...

Geomagnetic jerks are rapid time variations of the magnetic field at Earth's surface that thought to be primarily internal origin. Jerks relevant for studies Earth interior: they likely give information on core dynamics and possibly mantle electrical conductivity. In such a precise determination jerk occurrence its error bar each observatory is required. We analyze most well-known global (1969, 1978, 1991) possible local in 1999, considering all three components (X, Y, Z). Different data...

Abstract The equatorial electrojet occasionally reverses during morning and afternoon hours, leading to periods of westward current in the ionospheric E region that are known as counter (CEJ) events. We present first analysis CEJ climatology dependence on solar flux lunar phase for Brazilian sector, based an extensive ground‐based data set years 2008 2017 from geomagnetic observatory Tatuoca (1.2°S, 48.5°W), we compare it results found Huancayo (12.0°S, 75.3°W) Peruvian sector. a...

Abstract The magnetic equator in the Brazilian region has moved over 1,100 km northward since 1957, passing geomagnetic observatory Tatuoca (TTB), northern Brazil, around 2013. We recovered and processed TTB hourly mean values of field horizontal (H) component from 1957 until 2019, allowing investigation long‐term changes daily variation due to influence secular variation, solar activity, season, lunar phase. H day‐to‐day variability occurrence counter electrojet at were also investigated....

Worldwide jerks occurring in 1969, 1978 and 1991 are not simultaneous at the earth's surface, showing differential delays of about 2 yr. One way to explain this intriguing temporal pattern is consider mantle as a conductor. Consequently geomagnetic field observed surface will correspond filtered version original generated core–mantle boundary (CMB). We developed forward approach problem assuming part jerk impulse third time-derivative magnetic CMB. Two synthetic spherical harmonic models...

Abstract. In the last 60 years, largest displacement of magnetic equator (by about 1100 km northwards) occurred in Brazilian longitudinal sector. The passed by Tatuoca observatory (TTB) northern Brazil 2012 and continues to move northward. Due horizontal geomagnetic field geometry at equator, enhanced electric currents ionosphere are produced – so-called equatorial electrojet (EEJ). effect EEJ is observed range ±3° from where observatories record an amplified daily variation H component....

The process of magnetic field stretching transfers kinetic energy to and by that maintains dynamos against Ohmic dissipation. Stretching at the top outer core may play an important role specific regions. High-latitude intense flux patches be concentrated flow convergence. Reversed emerge due expulsion toroidal advected core–mantle boundary fluid upwelling. Here we analyze snapshots from self-consistent 3D numerical unravel nature field–flow interactions induces secular variation core. We...

Geomagnetic jerks are abrupt changes in the secular variation generated Earth's core. Even most basic characteristics of as its origin and duration, still a matter debate scientific community. Data obtained by magnetic observatories satellites used these studies. The main characteristic is that they not simultaneous at surface, with general pattern first arrival Northern hemisphere, later appearance South about two years. non-simultaneous behavior important to constrain electrical...

Geomagnetic jerks are sudden changes of trend in the geomagnetic secular variation. The Earth's mantle behaves as a filter for jerks, causing delayed and smoothed signal at surface. Backus' theory relies on approximating impulse response function (IRF) by Gaussian. advantage this is linear relation between jerks’ delay times electrical conductivity, expressed kernels. However, limitations arise when negative and/or smoothing occur. applicability examined analysing validity Gaussian an...

Abstract The intensity of the equatorial electrojet (EEJ) shows temporal and spatial variability that is not yet fully understood nor accurately modeled. Atmospheric solar tides are among main drivers this but determining different tidal components their respective time series challenging. It requires good coverage with observations, which, previously could only be achieved by accumulating data over many years. Here, we propose a new technique for modeling EEJ based on principal component...

Abstract Vertical magnetic transfer functions (tippers) estimated at island observatories can constrain the one-dimensional (1-D) conductivity distribution of oceanic lithosphere and upper mantle. This is feasible due to bathymetry-dependent ocean induction effect (OIE), which originates from lateral contrasts between land leads non-zero tippers even for 1-D distributions below ocean. Proper analysis requires accurate three-dimensional (3-D) modeling OIE, so far was performed assuming...

Dynamo models relying on the Babcock-Leighton mechanism are successful in reproducing most of solar magnetic field dynamical characteristics. However, considering that such operate only above a lower threshold, they do not provide an appropriate regeneration process characterizing self-sustainable dynamo. In this work we consider existence additional α-effect to scenario mean-field axisymmetric kinematic numerical model. Both poloidal mechanisms treated with two different strength-limiting...

Abstract. In the last 60 years, largest displacement of magnetic equator (by about 1100 km northwards) occurred in Brazilian longitudinal sector. The passed by Tatuoca observatory (TTB) northern Brazil 2012 and continues to move northward. Due horizontal geomagnetic field geometry at equator, enhanced electric currents ionosphere are produced – so called equatorial electrojet (EEJ). effect EEJ is observed range ± 3 degrees from where observatories record an amplified daily variation H...

Abstract. The Tatuoca magnetic observatory (IAGA code: TTB) is located on a small island in the Amazonian delta state Pará of Brazil. Its location close to geomagnetic equator and within South Atlantic Magnetic Anomaly offers high scientific return observatory's data. A joint effort by Observatorio Nacional, Brazil (ON) GFZ German Research Centre for Geosciences (GFZ) was undertaken starting from 2015 order modernize with goal join INTERMAGNET network provide real-time data access. In this...

ABSTRACT. Magnetic observatories are fundamental to study different magnetic sources, measuring precisely and continuously the geomagnetic field. The largest restriction of is their uneven distribution on Earth’s surface, especially in South America, where only few data available. In this work, we describe main steps for installation observatory Pantanal Region (Brazil) analysis a station that registered field from September 29th, 2011 up January 25th, 2012. From point view, interesting due...

The process of magnetic field stretching transfers kinetic energy to and thereby maintains dynamos against ohmic dissipation. Stretching at depth may play an important role in shaping the morphology dynamo action. Here, we analyze snapshots from self-consistent 3D numerical unravel nature field-flow interactions that induces secular variation radial mid-depth shell. We search for roots intense flux patches identified outer boundary. deep structures exhibit a position shift with respect...