Turbulence and Intermittency in the Solar Chromosphere

We study the line-of-sight velocity fluctuations measured simultaneously in a photospheric (Fe I 709.0 nm) and a chromospheric line (Ca II 854.2 nm). The velocities were obtained from imaging spectral scans acquired at high spatial resolution with the Interferometric BIdimensional Spectrometer (IBIS) covering an 80" diameter field in the quiet Sun. We find nearly power law tails above the acoustic cutoff frequency in the chromospheric velocity power spectra. The probability density functions (PDFs) of chromospheric velocity increments are non-Gaussian and asymmetric. Intermittency is much larger in the network than in fibril and internetwork regions. These results suggest that the small scale velocity fluctuations in the solar chromosphere are the result of a turbulent cascade generated from acoustic oscillations near the cutoff frequency. The role of this turbulent cascade for chromospheric heating is also discussed.