DYNAMICS OF SOLAR SUPERGRANULATION

This book is dedicated to the study of morphological and dynamical properties of supergranular cells with a view to investigate a possible turbulent origin of supergranulation. It focuses on how the size, lifetime, horizontal flow field and the fractal structure of the cells are related to each other. The data for the observations consisted of thirty three hours of full disc Dopplergrams obtained in June 1996 by the Michelson Doppler Interferometer on board the Solar and Heliospheric Observatory (SOHO). As a matter of policy all physical properties such as length scale, area, perimeter, lifetime and peak velocity field deduced from the digital images were obtained by visual inspection and manual processing, rather than, for example by cross-correlation or Fourier analysis. For instance, the size of a supergranular cell is obtained by parallel scans across the cell restricted by the observed cell boundary. The true size is obtained from the measured size by correcting for projection effects. The area-perimeter relation is used to evaluate the fractal structure.