AN ESTIMATE FOR THE SIZE OF CYCLE-23 BASED ON NEAR MINIMUM CONDITIONS

The first occurrence of a high-latitude, new cycle spot group for cycl e 23 was in May 1996, in conjunction with a minimum in the smoothed mo nthly mean sunspot number. Since then, new cycle spot groups have beco me more predominant, and the smoothed monthly mean sunspot number has slowly risen. Such behavior indicates that new cycle 23 probably had i ts minimum annual average sunspot number, R(min), equal to 8.7, in 199 6. Because this value is larger than the average for R(min), cycle 23 is expected to have a maximum amplitude, R(max), that, likewise, will be larger than average, suggesting further that it probably will be bo th fast rising (i.e., peaking before May 2000) and of shorter than ave rage length (i.e., ending before May 2007). Another parameter well cor related with R(max) is the minimum amplitude of the qa geomagnetic ind ex, aa(min), which usually occurs either in the year of R(min) occurre nce or, more often, in the following year. For 1996 the annual average of aa measured 18.6. Presuming this value to be an(min) for cycle 23, we calculate cycle 23's R(max) to be about 171.0 +/- 17.6 (i.e., the 90% prediction interval), based on the stronger (r = 0.98) bivariate f it of R(max) versus both R(min) and aa(min). Comparison of this estima te with others, using various combinations of parameters, yields an ov erlap in the prediction intervals for R(max) of about 168 +/- 15, a ra nge that is within the consensus recently reported by Joselyn et al. [ 1997] (= 160 +/- 30). Thus this study supports the view that cycle 23 will have an R(max) that will be larger than average but smaller than was seen for cycle 19, the largest cycle on record with R(max) = 190.2 .