ИСТИНА

Empirical determination of the scaling properties of space-time fluctuation of the Antarctic ice sheet presents a formidable challenge in testing and developing a theoretical understanding of equilibrium phenomena. The intended purpose is to improve our understanding of natural variability of the Antarctic ice sheet surface. Elevations for twelve ICESat campaign periods from February 2004 to February 2008 are used in this study. In addition, precipitation on a 1˚x1˚ latitude / longitude grid from Global Precipitation Climatology Project, currently available observation data are also taken into account. Our algorithm calculates short-time-scale elevation change rate at each point on a reference track. An array of points on repeat ground tracks is used to study surface’s fluctuation. We show that the mean difference in the height profile and precipitation must be identified as a vertical velocity from the physical consideration. We have yielded new insight into fluctuation of the ice sheet surface. The fractal approach has been used to describe surface fluctuation as a fractional Brownian motion (fBm). The variance of the height increment during the space lag is of the type , where is Hurst exponent. Fractional Brownian motion is a zero mean self-similar Gaussian process whose increments are stationary. These processes describe statistical equilibrium and steady states because of dynamical variables (height changes) are space -independent. This finding supported the hypothesis that fluctuation of surface were not random and that the interaction of precipitation with katabatic winds might be responsible for the observed long-term correlation in height changes with different scale. There is a highly significant difference between elevation change and snowfall rate owing to katabatic winds and associated drift loose snow. Cumulative snow transportation increase (uplift) or decrease (deflation) is 50 times larger than the magnitude of snowfall. The fluctuations are statistically self-similar within two scaling ranges [30, 5000m] and [3.5, 35km]. The fluctuation above the scaling range is statistically independent. This type of process is closely related to dynamic equilibrium. We found further scientific evidence for this theory of dynamic equilibrium in the Antarctic ice sheet