seas (version 0.2-1)

interarrival: Calculate the interarrivals between and within precipitation events

Description

Calculate the interarrivals (or spell periods), which are the number of days between precipitation events (dry days), and the number of days of continuous precipitation (wet days).

Usage

# minimum
interarrival(dat)
# with optional arguments
interarrival(dat, start, end, var = "precip", p.cut = 0.3,
             inv = FALSE, id)

Arguments

dat

data.frame, must have at least date and a field to calculate an interarrival with (such as precip)

start

start year; if omitted minimum year will be used

end

end year; if omitted will use same as start, and if start is omitted, will use maximum year

var

variable on to which the interarrivals are calculated; default is precip

p.cut

days with precipitation values greater than p.cut are considered to be wet days, and the complement are dry days; a trace amount of 0.3 mm is suggested

inv

logical; invert convention of the starting date such that the date is the first wet day if inv=FALSE (default), or the date is the first dry day if inv=TRUE

id

unique station identifier used to extract a subset of data from dat

Value

• interarrival object (which inherits the data.frame class) with date, wet, dry and fact fields (if supplied with a width value).

synopsis

interarrival(dat, start, end, var = "precip", p.cut = 0.3, inv = FALSE, id)

Details

The interarrival is the same as the spell period (i.e., dry spell), however this function simultaneously counts the number of dry and wet days relative to a single date. The date represents the first day of precipitation (if inv=TRUE, this convention is inverted to the first day of non-precipitation). Missing or NA precipitation values voids the number of counted days between and within segments, which implies that days without precipitation need to explicitly have zeros.

References

von Storch, H. and Zwiers, F.W., 1999, Statistical analysis in climate research, Cambridge: Cambridge University Press, 484 p.

See Also

plot.interarrival

Examples

data(mscdata)

van.int <- interarrival(mscdata, id=1108447)
plot(van.int, log=FALSE, maxy=30)