CorrectDOY {greenbrown} R Documentation

Correct day-of-year time series

Description

This function corrects a time series with days-of-years (e.g. start of growing season). For example, if the start of season occurs in one year at the end of the calendar year (doy > 305) and in another year at the beginning (doy < 60), the DOYs are corrected so that all values occur at the beginning of the year (e.g. negative DOYs will be produced) or at the end of the year (e.g. DOY > 365 will be produced). This function is applied in `Phenology` after phenology detection on sos, eos, pop and pot time series (see examples).

Usage

`CorrectDOY(doy, check.outliers = TRUE)`

Arguments

 `doy` a vector or time series representing DOYs `check.outliers` Set outliers to NA after correction? Outliers are defined here as: doy < (median - IQR*2) | doy > (median + IQR*2))

Value

a vector or time series

Author(s)

Matthias Forkel <matthias.forkel@geo.tuwien.ac.at> [aut, cre]

`Phenology`

Examples

```
# imagine the following start of season DOYs in 10 years
sos <- ts(c(15, 10, 12, 8, 10, 3, 362, 2, 1, 365), start=1982)
plot(sos)
# Visually, there seems to be big differences in the start of season. However,
# there is actually only one day between the last two values (DOY 1 = 1st January,
# DOY 365 = 31st December). Trend calculation fails on this time series:
plot(Trend(sos), ylab="SOS")

# The DOY time series needs to be corrected to analyze
# the true differences between days.
sos2 <- CorrectDOY(sos)
plot(Trend(sos2), ylab="SOS")
# The correction now allows trend analysis.
# Negative DOYs indicate days at the end of the previous year!

# other example
sos <- ts(c(5, 12, 15, 120, 363, 3, 362, 365, 360, 358), start=1982)
plot(sos) # one value seems like an outlier
sos2 <- CorrectDOY(sos)
plot(Trend(sos2), ylab="SOS")
# The outlier is removed.
# DOYs > 365 indicate days in the next year!

```

[Package greenbrown version 2.4.3 Index]