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GAP INTERPOLATION
The Akima Spline interpolates based on the gradients between points of the nearest neighbours in the time series. At least five neighbours are required (this may be satisfied by having two to three points on either side of a gap). The values of more distant neighbours appear to have little effect on the finally interpolated data.
Advantage is taken of this behaviour in the proposed variable length gap algorithm, as described here:
- For a given station an arbitrary length time series of data is selected.
- Points in the time series that satisfy a given quality condition are used to generate the Akima Spline. (in the first version of the algorithm only data where …