Persistence of solar activity on small scales: Hurst analysis of time series coming from H alpha flares

We calculated the Hurst exponent H for the daily averaged intensity Q of op tical flares, an index which describes the solar activity. We found that H similar or equal to0.74 +/-0.02 in the range of scales from about 20 days u p to 450 days. This value is well beyond H=1/2, expected for a stochastic B rownian process, thus indicating that the solar cycle could show persistenc e on small scales, in agreement with what has been found using other indice s of the solar cycle.