Phenology extraction in Inflection method (Zhang)

Phenology extraction in Inflection method (Zhang)

PhenoKl(
  fFIT,
  t = NULL,
  analytical = FALSE,
  smoothed.spline = FALSE,
  IsPlot = TRUE,
  show.legend = TRUE,
  ...
)

Arguments

fFIT

object return by curvefit()

t

doy vector, corresponding doy of vegetation index.

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?

IsPlot

whether to plot?

show.legend

whether show figure lelend?

...

Other parameters will be ignored.

Value

A numeric vector, with the elements of: Greenup, Maturity, Senescence, Dormancy.

References

1. Zhang, X., Friedl, M. A., Schaaf, C. B., Strahler, A. H., Hodges, J. C. F. F., Gao, F., … Huete, A. (2003). Monitoring vegetation phenology using MODIS. Remote Sensing of Environment, 84(3), 471–475. doi:10.1016/S0034-4257(02)00135-9

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)
#> sos eos 
#>  50 250 
PhenoDeriv(x)
#> sos pos eos 
#>  47 150 253 
PhenoGu(x)
#>  UD  SD  DD  RD 
#>  26  73 227 275 
PhenoKl(x)

#>    Greenup   Maturity Senescence   Dormancy 
#>         16         82        218        284