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The decomposition of oceanic flow into its balanced and unbalanced motions carries theoretical and practical significance for the oceanographic community. These two motions have distinct dynamical characteristics and affect the transport of…

System-scale magnetohydrodynamic (MHD) waves within Earth's magnetosphere are often understood theoretically using box models. While these have been highly instructive in understanding many fundamental features of the various wave modes…

Space Physics · Physics 2022-02-01 M. O. Archer , D. J. Southwood , M. D. Hartinger , L. Rastaetter , A. N. Wright

The calling card of solar magnetism is the sunspot cycle, during which sunspots regularly reverse their polarity sense every 11 years. However, a number of more complicated time-dependent behaviors have also been identified. In particular,…

Solar and Stellar Astrophysics · Physics 2020-04-06 Loren Matilsky , Juri Toomre

Dynamic mode decomposition (DMD) is a popular technique for modal decomposition, flow analysis, and reduced-order modeling. In situations where a system is time varying, one would like to update the system's description online as time…

Optimization and Control · Mathematics 2017-07-11 Hao Zhang , Clarence W. Rowley , Eric A. Deem , Louis N. Cattafesta

Little attention has been paid to group velocities of three-dimensional (3D) MHD waves in solar coronal seismology. This study aims to present a rather comprehensive examination on the group velocities of trapped 3D kink modes in coronal…

Solar and Stellar Astrophysics · Physics 2026-02-17 Jing Liu , Bo Li , Mijie Shi , Mingzhe Guo , Hui Yu

In this study we explore the possibility of simplifying the modeling of magnetohydrodynamic (MHD) slow body modes observed in photospheric magnetic structure such as the umbrae of sunspots and pores. The simplifying approach assumes that…

Solar and Stellar Astrophysics · Physics 2022-10-26 Anwar Aldhafeeri , Gary Verth , Viktor Fedun , Matthew Lennard , Istvan Ballai

Dynamic Mode Decomposition (DMD) is a data-driven modal decomposition technique that extracts coherent spatio-temporal structures from high-dimensional time-series data. By decomposing the dynamics into a set of modes, each associated with…

Fluid Dynamics · Physics 2026-05-05 Yutaro Tanaka , Hiroya Nakao

Diagnostics of MHD waves in the solar atmosphere is a topic which often encounters problems of interpretation, due partly to the high complexity of the solar atmospheric medium. Forward modeling can significantly guide interpretation,…

Solar and Stellar Astrophysics · Physics 2015-06-15 Patrick Antolin , Tom Van Doorsselaere

The long term study of the Sun is necessary if we are to determine the evolution of sunspot properties and thereby inform modeling of the solar dynamo, particularly on scales of a solar cycle. We aim to determine a number of sunspot…

Solar and Stellar Astrophysics · Physics 2011-08-23 Fraser T. Watson , Lyndsay Fletcher , Stephen Marshall

We aim to identify the physical processes which occur in the magnetic network of the chromosphere and which contribute to its dynamics and heating. Specifically, we study the propagation of transverse (kink) MHD waves which are impulsively…

Astrophysics · Physics 2009-11-10 S. S. Hasan , P. Ulmschneider

The Hinode satellite opens a new era to the sunspots research, because of its high spatial resolution and temporal stability. Fine scale structures in sunspots, called umbral dots (UDs), have become one of the hottest topics in terms of the…

Solar and Stellar Astrophysics · Physics 2015-06-22 Hiroko Watanabe

Dynamic mode decomposition (DMD) is utilised to identify the intrinsic signals arising from planetary interiors. Focusing on an axisymmetric quasi-geostrophic magnetohydrodynamic (MHD) wave -called torsional Alfv\'{e}n waves (TW) - we…

Fluid Dynamics · Physics 2020-09-29 Kumiko Hori , Steven M. Tobias , Robert J. Teed

High resolution and seeing-free spectroscopic observation of a decaying sunspot was done with the Solar Optical Telescope aboard Hinode satellite. The target was NOAA 10944 located in the west side of the solar surface from March 2 to March…

Astrophysics · Physics 2015-05-13 Hiroko Watanabe , Reizaburo Kitai , Kiyoshi Ichimoto , Yukio Katsukawa

We investigate p-mode absorption in a sunspot using SOHO/MDI high-resolution Doppler images. The Doppler power computed from a three and a half hour data set is used for studying the absorption in a sunspot. The result shows an enhancement…

Astrophysics · Physics 2008-09-11 Shibu K. Mathew

We present a linear analysis of inviscid, incompressible, magnetohydrodynamic (MHD) shallow water systems. In spherical geometry, a generic property of such systems is the existence of five wave modes. Three of them (two magneto-Poincare…

High Energy Astrophysical Phenomena · Physics 2015-05-13 Kevin Heng , Anatoly Spitkovsky

Magnetohydrodynamic (MHD) wave activity is ubiquitous in the solar atmosphere. MHD seismology aims to determine difficult to measure physical parameters in solar atmospheric magnetic and plasma structures by a combination of observed and…

Solar and Stellar Astrophysics · Physics 2015-06-04 Inigo Arregui

Magnetohydrodynamic (MHD) waves are candidates for heating the solar chromosphere, although it is still unclear which mode of the wave is dominant in heating. We perform two-dimensional radiative MHD simulation to investigate the…

Solar and Stellar Astrophysics · Physics 2021-08-04 Yikang Wang , Takaaki Yokoyama , Haruhisa Iijima

Dynamic mode decomposition (DMD), which the family of singular-value decompositions (SVD), is a popular tool of data-driven regression. While multiple numerical tests demonstrated the power and efficiency of DMD in representing data (i.e.,…

Numerical Analysis · Mathematics 2019-05-07 Hannah Lu , Daniel M. Tartakovsky

Transverse oscillations and propagating waves are frequently observed in threads of solar prominences/filaments and have been interpreted as kink magnetohydrodynamic (MHD) modes. We investigate the spatial damping of propagating kink MHD…

Solar and Stellar Astrophysics · Physics 2015-05-20 R. Soler , R. Oliver , J. L. Ballester

We analyse the temporal evolution of the inclination component of the magnetic field vector for the penumbral area of 25 isolated sunspots. Compared to previous works, the use of data from the HMI instrument aboard the SDO observatory…

Solar and Stellar Astrophysics · Physics 2020-03-11 A. B. Griñón-Marín , A. Pastor Yabar , H. Socas-Navarro , R. Centeno
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