• Publications
  • Influence
The Helioseismic and Magnetic Imager (HMI) Investigation for the Solar Dynamics Observatory (SDO)
The Helioseismic and Magnetic Imager (HMI) instrument and investigation as a part of the NASA Solar Dynamics Observatory (SDO) is designed to study convection-zone dynamics and the solar dynamo, theExpand
Design and Ground Calibration of the Helioseismic and Magnetic Imager (HMI) Instrument on the Solar Dynamics Observatory (SDO)
The Helioseismic and Magnetic Imager (HMI) investigation (Solar Phys. doi:10.1007/s11207-011-9834-2, 2011) will study the solar interior using helioseismic techniques as well as the magnetic fieldExpand
Comparison of Line-of-Sight Magnetograms Taken by the Solar Dynamics Observatory/Helioseismic and Magnetic Imager and Solar and Heliospheric Observatory/Michelson Doppler Imager
We compare line-of-sight magnetograms from the Helioseismic and Magnetic Imager (HMI) onboard the Solar Dynamics Observatory (SDO) and the Michelson Doppler Imager (MDI) onboard the Solar andExpand
Detection of Equatorward Meridional Flow and Evidence of Double-cell Meridional Circulation inside the Sun
Meridional flow in the solar interior plays an important role in redistributing angular momentum and transporting magnetic flux inside the Sun. Although it has long been recognized that theExpand
The NASA/NSO Spectromagnetograph
The NASA/NSO Spectromagnetograph is a new focal plane instrument for the National Solar Observatory/Kitt Peak Vacuum Telescope which features real-time digital analysis of long-slit spectra formed onExpand
Time–distance helioseismology
THE application of seismology to the study of the solar interior1, 2(helioseismology) has advanced almost solely by the prediction and measurement of the Sun's frequencies of free oscillation, orExpand
Observables Processing for the Helioseismic and Magnetic Imager Instrument on the Solar Dynamics Observatory
NASA’s Solar Dynamics Observatory (SDO) spacecraft was launched 11 February 2010 with three instruments onboard, including the Helioseismic and Magnetic Imager (HMI). After commissioning, HMI beganExpand
A subsurface flow of material from the Sun's equator to its poles
Gas on the Sun's surface has been observed to flow away from the equator towards both poles. If the same flow persists to great depths, it could play an important dynamical role in the eleven-yearExpand
Anomalously weak solar convection
Advection is dominated by Coriolis forces for wavenumbers ℓ < 60, with Rossby numbers smaller than approximately 10-2 at r/R⊙ = 0.96, suggesting that the Sun may be a much faster rotator than previously thought, and that large-scale convection may be quasi-geostrophic. Expand
Time-Distance Inversion Methods and Results – (Invited Review)
The current interpretations of the travel-time measurements in quiet and active regions on the Sun are discussed. These interpretations are based on various approximations to the 3-D wave equationExpand