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

We calculated the Hurst exponent H for the daily averaged intensity Q of optical 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 up to 450 days. This value is well beyond H=1/2, expected for a stochastic Brownian process, thus indicating that the solar cycle could show persistence on small scales, in agreement with what has been found using other indices of the solar cycle.