A digital filter initialization scheme has been introduced into the
HIRLAM model and compared to the reference implicit normal mode
initialization scheme. This report presents details of the scheme and
the results of extensive tests showing its advantages. The scheme is
shown to be more effective than the reference normal mode
initialization scheme in eliminating spurious high frequency noise from
the forecasts. In a parallel run using FASTEX data, the scores
produced by the DFI run were significantly better than those of the
reference run. The advantages of digital filter initialization
demonstrated in this report should justify the adoption of the digital
filtering initialization scheme as a new reference scheme for HIRLAM.