@Article{Kane:2008:HoUsWa,
               author = "Kane, Rajaram Purushottam",
          affiliation = "{Instituto Nacional de Pesquisas Espaciais (INPE)}",
                title = "How useful is the Waldmeier effect for prediction of a sunspot 
                         cycle?",
              journal = "Journal of Atmospheric and Solar-Terrestrial Physics",
                 year = "2008",
               volume = "70",
               number = "11/12",
                pages = "1533--1540",
                month = "Aug.",
             keywords = "Predictions, Sunspot cycle, Sunspot maxima, Waldmeier effect.",
             abstract = "Waldmeier effect [Waldmeier M., 1955. Ergebnisse und Probleme der 
                         Sonnenforschung. Second Ed., Leipzig, p. 154] states that the 
                         rise-time of a cycle depends upon a single parameter, namely the 
                         sunspot number Rz(max) at the maximum. Strong cycles have a 
                         steeper rise, while moderate cycles rise more slowly. In this 
                         paper, using the past data for sunspot cycles 1-23, these aspects 
                         are re-examined. It was noticed that the inverse relationship 
                         between Rz(max) and rise-time is discernable only when average 
                         patterns obtained by superposition of several cycles (separately 
                         for strong and weak cycles) are compared. In individual cycles, 
                         considerable deviations from the average patterns can occur 
                         (several tens of units of Rz and several months of rise-time). For 
                         a study of the relationship of Rz(max) with features in the early 
                         part of a cycle, the features chosen were Ro (i.e., Rz(min)) and 
                         Rz values Ra, Rb, and Rc, 12, 24 and 36 months, respectively, 
                         later than Ro (only 12-monthly running means were used). Ro had a 
                         moderate correlation (<0.6) with Rz(max), but Ra, Rb, Rc had 
                         better correlations. For hindsight predictions for cycles 18-23, 
                         the predictions for cycle 19 was grossly erroneous (observed value 
                         almost double of the predicted value). For other cycles, the 
                         errors were within 25%. For cycle 24, the Rz monthly values up to 
                         March 2008 give 12-month running means centered in June, July, 
                         August, September 2007 as 7.6, 6.5, 5.8, 6.1. Thus, though we 
                         cannot be absolutely sure yet that Rz(min) for cycle 24 has 
                         occurred, a tentative, provisional prediction using Rz(min) (i.e., 
                         Ro) as 5.8 is Rz(max)=113±19, i.e., in the range 94-132. This is 
                         an upper limit, as Ro value may reduce further in coming months, 
                         but most probably not very much. For Ro=5.0, the prediction would 
                         be Rz(max)= 109±17, while in the extreme hypothetical case of 
                         Ro=0.0, the prediction would be Rz(max)=79±14.",
                  doi = "10.1016/j.jastp.2008.04.010",
                  url = "http://dx.doi.org/10.1016/j.jastp.2008.04.010",
                 issn = "1364-6826",
             language = "en",
           targetfile = "how useful.pdf",
        urlaccessdate = "05 maio 2024"
}