72 citations · 279 across the 28 of their papers we have counts for
28 papers
Nonlinear evolution of unstable solar inertial modes: The case of viscous modes on a differentially rotating sphere
Muneeb Mushtaq, Damien Fournier, Rama Ayoub +2
On the Sun, the inertial mode with the largest observed amplitude (rms velocity exceeding m/s) is the high-latitude mode with longitudinal wavenumber . In two dimensions,…
3D Modeling of Solar Oscillations with Hybridizable Discontinuous Galerkin Method
Florian Faucher, Ha Pham, Damien Fournier +5
With increasing quantity and quality of solar observations, it becomes essential to account for three-dimensional heterogeneities in wave modeling for seismic data interpretation.…
Numerical simulations of oscillations for axisymmetric solar backgrounds with differential rotation and gravity
Ha Pham, Florian Faucher, Damien Fournier +2
Local helioseismology comprises of imaging and inversion techniques employed to reconstruct the dynamic and interior of the Sun from correlations of oscillations observed on the su…
Linear toroidal-inertial waves on a differentially rotating sphere with application to helioseismology: Modeling, forward and inverse problems
Tram Thi Ngoc Nguyen, Damien Fournier, Laurent Gizon +1
This paper develops a mathematical framework for interpreting observations of solar inertial waves in an idealized setting. Under the assumption of purely toroidal linear waves on…
Structure and Dynamics of the Sun's Interior Revealed by Helioseismic and Magnetic Imager
Alexander Kosovichev, Sarbani Basu, Yuto Bekki +43
High-resolution helioseismology observations with the Helioseismic and Magnetic Imager (HMI) onboard Solar Dynamics Observatory (SDO) provide a unique three-dimensional view of the…
Observations of eigenfunctions of solar inertial modes using local correlation tracking of magnetic features
Neelanchal Joshi, Zhi-Chao Liang, Damien Fournier +1
Solar inertial modes are quasi-toroidal modes of the Sun that are of practical interest as they allow probing the deep convection zone. Since 2010, solar images of the photospheric…
Solar Inertial Modes
Laurent Gizon, Yuto Bekki, Aaron C. Birch +5
The Sun's global inertial modes are very sensitive to the solar differential rotation and to properties of the deep solar convection zone which are currently poorly constrained. Th…
Inferring solar differential rotation and viscosity via passive imaging with inertial waves
Tram Thi Ngoc Nguyen, Thorsten Hohage, Damien Fournier +1
The recent discovery of inertial waves on the surface of the Sun offers new possibilities to learn about the solar interior. These waves are long-lived with a period on the order o…
Learned infinite elements for helioseismology -- Learning transparent boundary conditions for the solar atmosphere
Damien Fournier, Janosch Preuss, Thorsten Hohage +1
Context. Acoustic waves in the Sun are affected by the atmospheric layers, but this region is often ignored in forward models due to the increase in computational cost. Aims. The p…
Assembling algorithm for Green's tensors and absorbing boundary conditions for Galbrun's equation in radial symmetry
Ha Pham, Florian Faucher, Damien Fournier +2
Solar oscillations can be modeled by Galbrun's equation which describes Lagrangian wave displacement in a self-gravitating stratified medium. For spherically symmetric backgrounds,…
Quantitative passive imaging by iterative holography: The example of helioseismic holography
Björn Müller, Thorsten Hohage, Damien Fournier +1
In passive imaging, one attempts to reconstruct some coefficients in a wave equation from correlations of observed randomly excited solutions to this wave equation. Many methods pr…
Contribution of flows around active regions to the north-south helioseismic travel-time measurements
Paul-Louis Poulier, Zhi-Chao Liang, Damien Fournier +1
Context. In local helioseismology, the travel times of acoustic waves propagating in opposite directions along the same meridian inform us about horizontal flows in the north-south…
Viscous inertial modes on a differentially rotating sphere: Comparison with solar observations
Damien Fournier, Laurent Gizon, Laura Hyest
In a previous paper we studied the effect of latitudinal rotation on solar equatorial Rossby modes in the beta-plane approximation. Since then, a rich spectrum of inertial modes ha…
The Effect of Stellar Contamination on Low-resolution Transmission Spectroscopy: Needs Identified by NASA's Exoplanet Exploration Program Study Analysis Group 21
Benjamin V. Rackham, Néstor Espinoza, Svetlana V. Berdyugina +58
Study Analysis Group 21 (SAG21) of NASA's Exoplanet Exploration Program Analysis Group (ExoPAG) was organized to study the effect of stellar contamination on space-based transmissi…
Solar inertial modes: Observations, identification, and diagnostic promise
Laurent Gizon, Robert H. Cameron, Yuto Bekki +10
The oscillations of a slowly rotating star have long been classified into spheroidal and toroidal modes. The spheroidal modes include the well-known 5-min acoustic modes used in he…
Acoustic wave propagation through solar granulation: Validity of effective-medium theories, coda waves
P. -L. Poulier, D. Fournier, L. Gizon +1
Context. The frequencies, lifetimes, and eigenfunctions of solar acoustic waves are affected by turbulent convection, which is random in space and in time. Since the correlation ti…
C2 representations of the solar background coefficients for the model S-AtmoI
Florian Faucher, Damien Fournier, Ha Pham
We construct C2 representations of the background quantities that characterize the interior of the Sun and its atmosphere starting from the data-points of the standard solar model…
Effect of latitudinal differential rotation on solar Rossby waves: Critical layers, eigenfunctions, and momentum fluxes in the equatorial plane
L. Gizon, D. Fournier, M. Albekioni
Retrograde-propagating waves of vertical vorticity with longitudinal wavenumbers between 3 and 15 have been observed on the Sun with a dispersion relation close to that of classica…
Predicting frequency changes of global-scale solar Rossby modes due to solar cycle changes in internal rotation
C. R. Goddard, A. C. Birch, D. Fournier +1
Context. Large-scale equatorial Rossby modes have been observed on the Sun over the last two solar cycles. Aims. We investigate the impact of the time-varying zonal flows on the fr…
Signal and noise in helioseismic holography
Laurent Gizon, Damien Fournier, Dan Yang +2
Helioseismic holography is an imaging technique used to study heterogeneities and flows in the solar interior from observations of solar oscillations at the surface. Holograms cont…
Sensitivity kernels for time-distance helioseismology: efficient computation for spherically-symmetric solar models
Damien Fournier, Chris S. Hanson, Laurent Gizon +1
The interpretation of helioseismic measurements, such as wave travel-time, is based on the computation of kernels that give the sensitivity of the measurements to localized changes…
Comparison of Travel-Time and Amplitude Measurements for Deep-Focusing Time--Distance Helioseismology
Majid Pourabdian, Damien Fournier, Laurent Gizon
The purpose of deep-focusing time--distance helioseismology is to construct seismic measurements that have a high sensitivity to the physical conditions at a desired target point i…
Atmospheric radiation boundary conditions for high frequency waves in time-distance helioseismology
Damien Fournier, Michael Leguebe, Chris S. Hanson +4
The temporal covariance between seismic waves measured at two locations on the solar surface is the fundamental observable in time-distance helioseismology. Above the acoustic cut-…
Problems in computational helioseismology
Laurent Gizon, Damien Fournier, Thorsten Hohage
We discuss current advances in forward and inverse modeling for local helioseismology. We report theoretical uniqueness results, in particular the Novikov-Agaltsov reconstruction a…