Statistical Properties of Solar Granulation Derived from the Soup Instrument on Spacelab 2
PHILLIPS LAB HANSCOM AFB MA
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The Solar Optical Universal Polarimeter SOUP on Spacelab 2 collected movies of solar granulation completely free from the distortion and blurring introduced by the Earths 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 ms, while in magnetic regions it is about 125 ms. We have also found that the root mean square fluctuating horizontal velocity field in quiet Sun increases from 0.45 to 1.4 kms, and in strong magnetic field regions it increases from 0.3 to 0.75 kms as the measuring aperture decreases.