On the decay parameters of a ring current

Causes of divergence in ring current r decay parameter values obtained by various authors are discussed. Such causes can be: calculating errors in cases of tau determination by short duration intervals non account of the magnetic effect of surface currents, insufficiently strict selection of quiet intervals. An original method for tau determination excluding the possibility of enumerated above errors is suggested. The tau dependence on the ring current intensity according to which tau decreases with DR current growth is obtained. Using such dependence under simulation allows one to attain the minimum of quadratic error of calculated and observed values. It is shown that the effective model can be plotted only in case of monotonically decreased tau dependence on DR