Related Experiment Videos
GONG Observations of Solar Surface Flows
1D. H. Hathaway is in the Solar Physics Branch, Mail Code ES82, Space Sciences Laboratory, NASA/Marshall Space Flight Center, Huntsville, AL 35812, USA. P. A. Gilman is at the High Altitude Observatory, National Center for Atmospheric Research, Post Office Box 3000, Boulder, CO 80303, USA. J. W. Harvey, F. Hill, R. F. Howard, J. W. Leibacher, and J. A. Pintar are at the National Solar Observatory, National Optical Astronomy Observatories (NSO/NOAO), Post Office Box 26732, Tucson, AZ 85726-6732, USA. H. P. Jones is at NASA/Goddard Space Flight Center, Southwest Solar Station, NSO/NOAO, Post Office Box 26732, Tucson, AZ 85726-6732, USA. J. C. Kasher is in the Physics Department, University of Nebraska at Omaha, 64th and Dodge Streets, Omaha, NE 68182-0266, USA. G. W. Simon is at Air Force Materiel Command, Phillips Laboratory, Geophysics Directorate, Solar Research Branch, NSO, Sunspot, NM 88349, USA.
Global Oscillation Network Group (GONG) observations reveal solar surface flows, including differential rotation and a north-south asymmetry. Torsional oscillations and meridional circulation suggest the presence of large convection cells.
Area of Science:
- Solar physics
- Helioseismology
- Plasma dynamics
Background:
- The Sun's surface exhibits complex flows, including differential rotation and meridional circulation.
- Understanding these flows is crucial for comprehending solar activity and its influence on space weather.
Purpose of the Study:
- To analyze Doppler velocity observations from the Global Oscillation Network Group (GONG) instruments.
- To characterize the nearly steady flows in the solar photosphere, including differential rotation, torsional oscillations, and meridional circulation.
Main Methods:
- Direct measurement of Doppler velocity using GONG instruments.
- Analysis of rotation profiles with respect to latitude.
- Averaging rotation profiles over 27-day solar rotations to identify temporal variations.
Main Results:
- Accurate determination of the Sun's differential rotation profile, showing agreement with previous measures but also a slight north-south asymmetry.
- Detection of torsional oscillations, characterized by weak, jetlike features (5 m/s amplitude) associated with sunspot activity belts.
- Evidence of a poleward meridional circulation with a flow of approximately 20 m/s.
Conclusions:
- The observed surface flows provide insights into the Sun's internal dynamics.
- Characteristics of the flows suggest the presence of large-scale convection cells driving surface phenomena.
- The findings contribute to a more comprehensive understanding of solar dynamics and activity cycles.