34th Solar Physics Division Meeting, June 2003
Session 7 Photosphere and Chromosphere I
Poster, Monday, June 16, 2003, 3:30-5:00pm, Mezzanine

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[7.02] Evolution of the Granular Dynamics and Energy Transport

A. Nesis, R. Hammer, H. Schleicher (Kiepenheuer-Institut fuer Sonnenphysik)

Based on series of excellent spectrograms taken at the German Vacuum Tower Telescope (VTT) at the Observatorio del Teide (Tenerife), we study the temporal evolution of the granular dynamics and the energy transport in the photospheric layers. We consider the ensemble of the granules cut by the spectrograph slit as a complex system. We describe this ensemble by the rms of the fluctuations of the granular observables along the slit: continuum intensity I, Doppler velocity v, and line width w. The history of the rms of the observables v and w reflects the dynamical change of the system over the 20 minutes observation time. We find for both observables a quasi-periodical change. However, the history of the cross-correlation between I and v remains virtually constant, with the exception of two gaps. We measure the rms of v in the deep photospheric layers for six lines of different strength included in the spectrograms. Using a model velocity variation based on our previous publications, we assign photospheric heights to the velocity measurements. These heights agree with those calculated by other means. On the basis of this v variation we calculate the kinetic energy flux as a function of the height in the photosphere for different times during the observation. The form of the variation with height turns out to be constant in time. The convective energy flux, finally, is calculated from the measured velocity and the temperature variations of our earlier models. Again we find practically the same variation form over the time of the observation. Taken together, these results quantify the different roles that the lower and higher photospheric layers play for the energetics of the convective overshoot at the upper boundary of the superadiabatic region of the Sun.

A.N. acknowledges travel support from the German science foundation DFG.

The author(s) of this abstract have provided an email address for comments about the abstract: nesis@kis.uni-freiburg.de

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Bulletin of the American Astronomical Society, 35 #3
© 2003. The American Astronomical Soceity.