Using Data Prior To 1980 To Predict The Shape Of The Entire Drift Function

  The accurate expected values from the first 100 years of anomaly data can be used to predict the shape of the entire drift function. I extracted the anomalies prior to 1980 from the monthly global land anomaly data and determined a separate set of points for the drift function. Then a fit was found using the most accurately known points for the curve. The prediction of what the entire drift function would look like is consistent with the curve found by using all the data. The expected values were slightly different for the earlier data since there was less data to work with and the frequencies were reduced somewhat. The earlier data and fit are shown in blue in the plot below.