Statistical Properties of Solar Granulation Derived from the Soup Instrument on Spacelab 2
Abstract
The Solar Optical Universal Polarimeter (SOUP) on Spacelab 2 collected movies of solar granulation completely free from the distortion and blurring introduced by the Earth's atmosphere. Individual images in the movies are diffraction-limited (30 cm aperture) and are not degraded by pointing jitter. The movies illustrate that the solar 5 minute oscillation has a major role in the appearance of solar granulation and that exploding granules are a common feature of the granule evolution. Using three-dimensional Fourier filtering techniques, we have been able to remove the oscillations and demonstrate that they dominate the temporal autocorrelation functions of the granulation pattern. When the oscillations are removed, the autocorrelation lifetime of granulation is a factor of 2 greater in magnetic field regions than in field-free quiet Sun. Using a technique called local correlation tracking, we have been able to measure horizontal velocities and observe flow patterns on the scale of meso- and supergranulation. In quiet regions the mean flow velocity is 370 m/s, while in magnetic regions it is about 125 m/s. We have also found that the root mean square fluctuating horizontal velocity field in quiet Sun increases from 0.45 to 1.4 km/s, and in strong magnetic field regions it increases from 0.3 to 0.75 km/s as the measuring aperture decreases.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 1989
- Accession Number
- ADA282018
Entities
People
- A. M. Title
- K. P. Topka
- R. A. Shine
- S. H. Ferguson
- T. D. Tarbell
Organizations
- Phillips Laboratory