Compute CWD and CDD with custom threshold

[ysubash]

I wish to compute the Consecutive wet and dry days with custom threshold of 2.5 mm. The default threshold is 1 mm. Is it possible ?

[thiagoveloso]

@ysubash you can always create your own custom function. If you're on RStudio, you can type View and take a look at the function code. For cdd:

function (ci, spells.can.span.years = TRUE) 
{
  stopifnot(!is.null(ci@data$prec))
  return(spell.length.max(ci@data$prec, ci@date.factors$annual, 
    1, "<", spells.can.span.years) * ci@namasks$annual$prec)
}

where the number 1 is the default value the function is using. Then you can change it to, say:

climdex.cdd.2.5 <- function (ci, spells.can.span.years = TRUE) 
{
  stopifnot(!is.null(ci@data$prec))
  return(spell.length.max(ci@data$prec, ci@date.factors$annual, 
    2.5, "<", spells.can.span.years) * ci@namasks$annual$prec)
}

where the new value used is 2.5. You can even define a generic function, using a custom threshold:

climdex.cdd.cus <- function (ci, spells.can.span.years = TRUE, thre) 
{
  stopifnot(!is.null(ci@data$prec))
  return(spell.length.max(ci@data$prec, ci@date.factors$annual, 
    thre, "<", spells.can.span.years) * ci@namasks$annual$prec)
}