rainequation: Rain equation

In metno/esd: Climate analysis and empirical-statistical downscaling (ESD) package for monthly and daily data

Rain equation

Description

The rain equation Pr(X>x)=fw exp(-x/mu) estimates the likelihood of 24-hr precipitation exceedint a threshold value x. It is analogous to the normal distribution used to describe the statistical distribution of e.g. daily temperature over a season, but applied to precipitation. It has two parameters, the wet-day frequency fw and the wet-day mean mu. It assumes that the distribution for wet-day precipitation can be approximated with an exponential distribution, and has one tail.

Usage

rainequation(x, x0 = 10, threshold = NULL)

Arguments

x	A station object - single station
x0	The threshold value defining an event.
threshold	The threshold defining a 'wet day'.
src	Data source
nmin	Minimum number of years with data
verbose	TRUE for printing out diagnostics
colour.by	Used to plot the data points with differentcolours according to e.g. 'x0', 'stid', 'alt', 'lon', or 'lat'
col	colour palette

Details

The function rainvar returns the dail variance of the 24-hr precipitation according to sigma^2 = 2 fw * mu^3 and rainvartrend calculates the first derivative accroding to d sigma^2/dt = 2 mu^3 dfw/dt + 6 fw mu^2 dmu/dt. concise (1-5 lines) description of what the function does. ~~

Value

a station object

References

Benestad R. and A. Mezghani (2015), On downscaling probabilities for heavy 24-hr precipitation events at seasonal-to-decadal scales, Tellus A 2015, 67, 25954, http://dx.doi.org/10.3402/tellusa.v67.25954

Examples

data(bjornholt)
plot(rainequation(bjornholt))
test.rainequation(bjornholt,threshold=30)
## Not run: scatterplot.rainequation()

metno/esd documentation built on Feb. 25, 2025, 6:44 p.m.