phenofit (version 0.3.9)

PhenoGu: Phenology extraction in GU method (GU)

Description

Phenology extraction in GU method (GU)

Usage

PhenoGu(x, t, ...)
# S3 method for fFIT
PhenoGu(x, t = NULL, analytical = FALSE, smoothed.spline = FALSE, ...)
# S3 method for default
PhenoGu(x, t, der1, IsPlot = TRUE, ...)

Value

A numeric vector, with the elements of:

• UD: upturn date

• SD: stabilisation date

• DD: downturn date

• RD: recession date

Arguments

x

numeric vector, or fFIT object returned by curvefit().

t

doy vector, corresponding doy of vegetation index.

...

other parameters to PhenoGu.default() or PhenoGu.fFIT()

analytical

If true, numDeriv package grad and hess will be used; if false, D1 and D2 will be used.

smoothed.spline

Whether apply smooth.spline first?

der1

the first order difference

IsPlot

whether to plot?

References

1. Gu, L., Post, W. M., Baldocchi, D. D., Black, T. A., Suyker, A. E., Verma, S. B., … Wofsy, S. C. (2009). Characterizing the Seasonal Dynamics of Plant Community Photosynthesis Across a Range of Vegetation Types. In A. Noormets (Ed.), Phenology of Ecosystem Processes: Applications in Global Change Research (pp. 35–58). New York, NY: Springer New York. tools:::Rd_expr_doi("10.1007/978-1-4419-0026-5_2")

2. Filippa, G., Cremonese, E., Migliavacca, M., Galvagno, M., Forkel, M., Wingate, L., … Richardson, A. D. (2016). Phenopix: A R package for image-based vegetation phenology. Agricultural and Forest Meteorology, 220, 141–150. tools:::Rd_expr_doi("10.1016/j.agrformet.2016.01.006")

Examples

# `doubleLog.Beck` simulate vegetation time-series
t    <- seq(1, 365, 8)
tout <- seq(1, 365, 1)
par  = c( mn  = 0.1 , mx  = 0.7 , sos = 50 , rsp = 0.1 , eos = 250, rau = 0.1)
y <- doubleLog.Beck(par, t)

methods <- c("AG", "Beck", "Elmore", "Gu", "Zhang") # "Klos" too slow
fit <- curvefit(y, t, tout, methods)
x <- fit$model$AG # one model

par(mfrow = c(2, 2))
PhenoTrs(x)
PhenoDeriv(x)
PhenoGu(x)
PhenoKl(x)