The fort.23 file contains wave radiation stresses that can be used by themselves or in concert with other forcing (including winds) to drive ADCIRC. The wave radiation stress input file is read when ABS(NWS)>=100 in the fort.15 file. The format is similar to the meteorological input file used when NWS =-4 (i.e. the PBL hurricane model input format following a hot start).
See fort.23 file format for details.