@BeginModule
@Name      = EcaGsl
@Title     = Growing season length index
@Section   = ECA indices
@Class     = ECA index
@Arguments = ifile ofile
@Operators = eca_gsl

@BeginDescription
Let @file{ifile} be a time series of daily mean temperatures TG,
then counted are the number of days between the first occurrence
of at least nday consecutive days with TG > T and the first occurrence
after 1 July of at least nday consecutive days with TG < T. The
numbers nday and T are optional parameter with default nday = 6
and T = 5° Celsius. Further output variables are the start and end
dates of the growing season. Note that TG must be given in units of
kelvin.
The date information for a time step in @file{ofile} is the date of
the last contributing time step in @file{ifile}.
@EndDescription
@EndModule


@BeginOperator_eca_gsl
@Title     = Growing season length index
@Parameter = [nday] [T]
@EndOperator


@BeginParameter
@Item = nday
INTEGER  Number of consecutive days (default: nday = 6)
@Item = T
FLOAT    Temperature threshold (° Celsius, default: T = 5° Celsius)
@EndParameter


@BeginExample
To get the growing season length for a time series of daily
mean temperatures, use:
@BeginVerbatim
   cdo eca_gsl tgfile ofile
@EndVerbatim
@EndExample
