CLIMATIC NORMALS AS PREDICTORS. PART 5. CONCLUSION
Final rept. Dec 1965-Dec 1968
SAN FERNANDO VALLEY STATE COLL NORTHRIDGE CA
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Methods of previous Reports, concerned with the number of antecedent years for which the mean value of a climatic element offers the minimum variance estimator of the next years value, are extended to similar predictions more than one year ahead. For predicting a value m years beyond the end of the averaging period, the best average is found to be based on a period m years shorter than for predicting the next years value. Apparently each climatic record has an average period of maximum homogeneity, whose length must be equalled, for optimum prediction, by the interval from the start of the averaging period to the end of the predicted one. Climatic normals for 15-year periods, rather than 30 years as at present, are recommended, with recomputation every 5 years. Medians of values over 15 years are suggested as even better predictors than means. Finally, 7 years is suggested as a suitable period for the definition of climate.