Experimental observation of 1/f noise in quasi-bidimensional turbulent flows

We report the experimental observation of 1/fα noise in quasi-bidimensional turbulence of an electromagnetically forced flow. The large-scale velocity UL exhibits this power-law spectrum with α 0.7 over a range of frequencies smaller than both the characteristic turnover frequency and the damping rate of the flow. By studying the statistical properties of sojourn time in each polarity of UL, we demonstrate that the 1/fα noise is generated by a renewal process, defined by a two-state model given by the polarities of the large-scale circulation. The statistical properties of this renewal process are shown to control the value of the exponent α.