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The torsional oscillation and the new solar cycle
Thompson, M. J.; Howe, R.; Komm, R. +5 more
We present updated observations of the pattern of migrating solar zonal flows known as the torsional oscillation, covering 15 years of helioseismic measurements with GONG and MDI and 30 years of surface Doppler observations from Mount Wilson. We compare the behavior of the flows during the extended solar minimum following Cycle 23 with that in ear…
First Global Rotation Inversions of HMI Data
Thompson, M. J.; Howe, R.; Komm, R. +4 more
We present the first 2-dimensional global rotational inversions of medium-degree p-mode data from the Helioseismic and Magnetic Imager, and compare the results with inversions of Michelson Doppler Imager data for the same time period. The inferred rotation profiles show good agreement between the two instruments.
Solar-cycle variation of zonal and meridional flow
Howe, R.; Komm, R.; Hill, F. +2 more
We study the variation with the solar cycle of the zonal and meridional flows in the near-surface layers of the solar convection zone. We have analyzed MDI Dynamics-Program data with ring-diagram analysis covering the rising phase of cycle 23, while the analyzed GONG high-resolution data cover the maximum and declining phase of cycle 23. For the z…
New insights on the solar core
Eff-Darwich, A.; García, R. A.; Garrido, R. +11 more
Since the detection of the asymptotic properties of the dipole gravity modes in the Sun, the quest to find individual gravity modes has continued. An extensive and deeper analysis of 14 years of continuous GOLF/SoHO observational data, unveils the presence of a pattern of peaks that could be interpreted as individual dipole gravity modes in the fr…
Are recent solar heavy element abundances consistent with helioseismology?
Basu, Sarbani; Antia, H. M.
During the last decade the abundances of heavy elements in the Sun have been revised downwards leading to serious discrepancy between solar models constructed using these abundances and the available seismic data. Much of these downward revision of abundances of Oxygen and other light elements was attributed to use of improved 3D solar atmospheric…
Ring-analysis flow measurements of sunspot outflows
Thompson, Michael J.; Featherstone, Nicholas A.; Hindman, Bradley W.
We present a local helioseismological analysis of the convective flows around sunspots. The flow deductions were obtained from MDI Dopplergrams using ring-analysis techniques to measure Doppler shifts induced in solar acoustic oscillations. A novel multi-scale 3-D inversion procedure was used to self-consistently combine all ring-analysis data tak…
The acoustic low-degree modes of the Sun measured with 14 years of continuous GOLF & VIRGO measurements
García, R. A.; Mathur, S.; Jiménez, A. +3 more
The helioseismic Global Oscillation at Low Frequency (GOLF) and the Variability of solar Irradiance and Gravity Oscillations (VIRGO) instruments onboard SoHO, have been observing the Sun continuously for the last 14 years. In this preliminary work, we characterize the acoustic modes over the entire p-mode range in both, Doppler velocity and lumino…
Are short-term variations in solar oscillation frequencies the signature of a second solar dynamo?
Chaplin, William J.; García, Rafael A.; Basu, Sarbani +6 more
In addition to the well-known 11-year solar cycle, the Sun's magnetic activity also shows significant variation on shorter time scales, e.g. between one and two years. We observe a quasi-biennial (2-year) signal in the solar p-mode oscillation frequencies, which are sensitive probes of the solar interior. The signal is visible in Sun-as-a-star dat…
Rotation-rate variations at the tachocline: An update
Thompson, M. J.; Howe, R.; Komm, R. +5 more
After 15 years of GONG and MDI observations of the solar interior rotation, we revisit the issue of variations in the rotation rate near the base of the convection zone. The 1.3-year period seen in the first few years of the observations disappeared after 2000 and has still not returned. On the other hand, the agreement between GONG and MDI observ…
Global p-mode oscillations throughout the complete solar cycle 23 and the beginning of cycle 24
García, R. A.; Pallé, P. L.; Jiménez, A. +1 more
The parameters of the p-mode oscillations vary with solar activity. Such temporal variations provide insights for the study of the structural and dynamical changes occurring in the Sun's interior throughout the solar cycle. We present here a complete picture of the temporal variations of the global p-mode parameters (excitation, damping, frequency…