Time dependent correlations in marine stratocumulus cloud base height records

The scaling ranges of time correlations in the cloud base height records of marine boundary layer stratocumulus axe studied applying the Detrended Fluctuation Analysis statistical method. We have found that time dependent variations in the evolution of the a exponent reflect the diurnal dynamics of cloud base height fluctuations in the marine boundary layer. In general a more stable structure of the boundary layer corresponds to a lower value of the a-indicator, i.e., larger anti-persistence, thus a set of fluctuations tending to induce a greater stability of the stratocumulus. In contrast, during the periods of higher instability in the marine boundary, less anti-persistent (more persistent like) behavior of the system drags it out of equilibrium, corresponding to larger a values. From an analysis of the frequency spectrum, the stratocumulus base height evolution is found to be a nonstationary process with stationary increments. The occurrence of these statistics in cloud base height fluctuations suggests the usefulness of similar studies for the radiation transfer dynamics modeling.