odd and even cycles determines the expected values of Xomax and Adr. In this Section we try to solve the inverse problem of determining Adr and Xomax only on the basis of data during solar cycle 22 (Dorman, 2003a,b). We will therefore correct the observed CR long-term variation in cycle 22 for drift effects with different values of the amplitude Adr; for each Adr we determine the correlation coefficient R(Xo,Adr) of corrected CR long-term variation according to a convection-diffusion model for different values of the time-lag Xo (from 0 to 60 av. months with monthly steps). Then we determine the value of Xomax(Adr) when R(xo,Adr) reaches the maximum value Rmax (xomax,Adr). For each Adr we will determine Rmax and Xomax . It is natural to assume that the most reliable value of Adr will correspond to the biggest Rmax(xomax,Adr) value, i.e. when the correction for drift effects is the best (in the frame of the model used for drift effects for long-term CR variations). By this way will be also possible to determine the most reliable value for Xomax characterizing the dimension of the CR modulation region in the Heliosphere. We will base on the convection-diffusion quasi-stationary model of CR-SA hysteresis phenomenon which was described in detail in Section 2.45.3 (Eqs. 2.45.1-2.45.5), and on drift model (both these models were used in Section 2.45.4). According to the main idea of the drift mechanism (see Jokipii and Davila, 1981; Jokipii and Thomas, 1981; Lee and Fisk, 1981; Kota and Jokipii, 1999; Burger and Potgieter, 1999; Ferreira et al., 1999) we assume that the drift's CR amplitude are proportional to the value of tilt angle T and changed sign during periods of the SMF polarity reversal. Important for the cycle 22 reversal periods are: March 1981±5 months and June 1991±7 months. The expected drift effect according to this model for the period January 1985-December 1996 is shown in Fig. 2.45.3 for the 11-month-smoothed data of W and Adr =1% at W=75.

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