@BeginModule
@NewPage
@Name      = EcaHwfi
@Title     = Warm spell days index wrt 90th percentile of reference period
@Section   = Climate indices
@Class     = Climate index
@Arguments = ifile1 ifile2 ofile
@Operators = eca_hwfi

@BeginDescription
Let @file{ifile1} be a time series of daily mean temperatures TG, and 
@file{ifile2} be the 90th percentile TGn90 of daily mean temperatures
for any period used as reference. Then counted is the number of days
where, in intervals of at least nday consecutive days, TG > TGn90. The
number nday is an optional parameter with default nday = 6. A further
output variable is the number of warm-spell periods longer than or
equal to nday days. 
TGn90 is calculated as the 90th percentile of daily mean temperatures of a five 
day window centred on each calendar day of a given climate reference period.
Note that both TG and TGn90 have to be given in the same units.
The date information of a timestep in @file{ofile} is the date of
the last contributing timestep in @file{ifile1}.
@EndDescription
@EndModule


@BeginOperator_eca_hwfi
@Title     = Warm spell days index wrt 90th percentile of reference period
@Parameter = [nday]
@EndOperator


@BeginParameter
@Item = nday
INTEGER  Number of consecutive days (default: nday = 6)
@EndParameter


@BeginExample
To compute the number of warm-spell days of a time series of
daily mean temperatures use:
@BeginVerbatim
   cdo eca_hwfi tgfile tgn90file ofile
@EndVerbatim
@EndExample
