@BeginModule
@NewPage
@Name      = EcaTr
@Title     = Tropical nights index per time period
@Section   = Climate indices
@Class     = Climate index
@Arguments = ifile ofile
@Operators = eca_tr

@BeginDescription
Let @file{ifile} be a time series of daily minimum temperatures TN,
then counted is the number of days where TN > T. The number T is
an optional parameter with default T = 20 @celsius. Note that TN
have to be given in units of Kelvin, whereas T have to be given in degrees Celsius.
The date information of a time step in @file{ofile} is the date of
the last contributing time step in @file{ifile}.
@EndDescription
@EndModule


@BeginOperator_eca_tr
@Title     = Tropical nights index per time period
@Parameter = [T]
@EndOperator


@BeginParameter
@Item = T
FLOAT   Temperature threshold (° Celsius, default: T = 20° Celsius)
@EndParameter


@BeginExample
To get the number of tropical nights of a time series of daily
minimum temperatures use:
@BeginVerbatim
   cdo eca_tr tnfile ofile
@EndVerbatim
@EndExample
