springpheno (version 0.5.0)

synval: Synoptic Event Identifier

Description

This function identifies if a given period is a synoptic warm event which would help trigger plant growth. This function requires the growing degree hours for the current day and the growing degree hours for the prior seven days. Finally, this function will calculate if a period will trigger growth for first leaf or first bloom. The formulas for this calculation are based on the original Matlab code for the extended spring indices (SI-x, Ault et al. 2015)

Usage

synval(GDH, lagGDH, type = "leaf")

Arguments

GDH

Scalar - growing degree hours for a given day

lagGDH

Vector - growing degree hours for the 7 previous days. Must be a vector of at least a length 7 or the function will throw an error.

type

Either leaf (default) to identify events contributing to first leaf, or bloom to identify events contributing to first bloom.

Value

The output is a list with the following:

synflag

Scalar - synoptic event flag. Has a value of 1 if a synoptic event happened, value of 0 otherwise.

dde2

Scalar - sum of growing degree hours for current day and previous two days.

dd57

Scalar - sum of growing degree hours 5-7 prior to current day.

References

Ault, T.R., R. Zurita-Miller and M. Schwarz, 2015: A Matlab<U+00A9> toolbox for calculating spring indices from daily meteorological data. Computers and Geosciences, 83, DOI: 10.1016/j.cageo.2015.06.015

Examples

# NOT RUN {
daystop <- 240
lat <- 35.476 # latitude for OKC
daylen <- daylength(daystop=daystop,lat=lat)

tmax <- rep(65,daystop)
tmin <- rep(42,daystop)
bt <- 31

gdh <- c()

for(i in 1:daystop){
gdh[i] <- growdh(tmax[i],tmin[i],daylen[i],bt)
}

idx <- 60
lagidx <- idx - 1:7

laggdh <- gdh[lagidx]

result <- synval(gdh[idx],laggdh,type="leaf")

# }