Multi-fractal structure of the dissipation field of intensity fluctuationsin the solar photosphere

We investigate the scaling properties of the photospheric intensity field, using images acquired at the THEMIS telescope with the Italian Panoramic Mo nochromator. After calculating the power spectrum of the continuum intensit y fluctuations, we analyze the scaling laws of the dissipation field obtain ed from the intensity fluctuations, in analogy with the dissipation of pass ive scalar fluctuations in turbulent fluids. Using the multifractal formali sm, we show that the dissipation is intermittent and that it is characteriz ed by stronger singularities in the higher photosphere than in the lower ph otosphere. (C) 2000 Elsevier Science B.V. All rights reserved.