GONG Observations of Solar Surface Flows
Doppler velocity observations obtained by the Global Oscillation Network Group (GONG) instruments directly measure the nearly steady flows in the solar photosphere. The sun's differential rotation is accurately determined from single observations. The rotation profile with respect to latitude agrees well with previous measures, but it also shows a slight north-south asymmetry. Rotation profiles averaged over 27-day rotations of the sun reveal the torsional oscillation signal-weak, jetlike features, with amplitudes of 5 meters per second, that are associated with the sunspot latitude activity belts. A meridional circulation with a poleward flow of about 20 meters per second is also evident. Several characteristics of the surface flows suggest the presence of large convection cells.
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D. 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.
Gilman
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Harvey
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Hill
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Howard
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Jones
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Kasher
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Leibacher
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Pintar
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Simon
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