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Title: Effects of certain analysis procedures on solar global velocity signals

We examine the data reduction procedures used by Howard and colleagues to deduce global solar velocities from the orginal Mount Wilson Doppler-magnetograph record. We demonstrate that removing daily rotation ''ears,'' and zero offset signals will greatly attenuate east-west global velocities of longitudinal wavenumber m< or =5. In addition we show that, because global velocity patterns are expected on theoretical grounds to have variable phase speeds in longitude, the construction of synoptic maps can severely attenuate high wavenumbers. The combination of these two effects can easily reduce an original periodic east-west flow velocity of peak amplitude 100 m s/sup -1/ to 10 m s/sup -1/ or less for any wavenumber. We demonstrate further that a velocity spectrum, obtained from a nonlinear spherical convection model for a case in which a differential rotation similar in amplitude and profile to the Sun, is attenuated to rms residual velocities close to or within the upper limits obtained by Howard and LaBonte. However, somewhat more power than they find is retained in variations of the daily rotation rate.
Authors:
;
Publication Date:
OSTI Identifier:
6636041
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophys. J.; (United States); Journal Volume: 241:2
Research Org:
High Altitude Observatory, National Center for Atmospheric Research, Boulder, Colorado
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; SOLAR ATMOSPHERE; CONVECTION; ROTATION; VELOCITY; AMPLITUDES; DATA ANALYSIS; PHASE VELOCITY; SOLAR ACTIVITY; ATMOSPHERES; MOTION 640104* -- Astrophysics & Cosmology-- Solar Phenomena