Improved McNish&Lincoln predictions

Improved 12-month ahead predictions obtained by applying an adaptative Kalman filter to the primary McNish and Lincoln predictions from NOAA/NGDC. This technique improves the approximation of the smoothed monthly sunspot number over the last 6 months, i.e. the interval between the last available smoothed value of the sunspot number and the current month of the prediction.
(Ref.: T. Podladchikova, R. Van der Linden, 2011: "A Kalman Filter Technique for Improving Medium-Term Predictions of the Sunspot Number". Solar Physics. DOI: 10.1007/s11207-011-9899-y)

The original predictions are taken from NOAA/NGDC at:
ftp://ftp.ngdc.noaa.gov/STP/space-weather/solar-data/solar-indices/sunspot-numbers/predicted
A description of the base McNish & Lincon prediction method can be found in:
- McNish, A.G. and Lincoln, J.V., 1949, “Prediction of sunspot numbers”, Eos Trans. AGU, 30, 673–685
- Steward, F.G., Ostrow, S.M., 1970, Journal des Télécommunications, 37, 228.