The Huglin index is used in viticulture to characterise the thermal
potential of a region for grape growing. It is computed over the growing
season (April 1 to September 30 in the Northern Hemisphere; October 1 to
March 31 in the Southern Hemisphere).
Usage
ck_huglin(tmin, tmax, dates, lat)
Arguments
- tmin
Numeric vector of daily minimum temperatures (degrees C).
- tmax
Numeric vector of daily maximum temperatures (degrees C).
- dates
Date vector of the same length as tmin.
- lat
Numeric. Latitude in decimal degrees (used to determine
hemisphere and day-length coefficient).
Value
A data frame with columns period, value, index, and unit.
References
Huglin, P. (1978). Nouveau mode d'evaluation des possibilites
heliothermiques d'un milieu viticole. Comptes Rendus de l'Academie
d'Agriculture de France, 64, 1117-1126.
Examples
dates <- seq(as.Date("2024-04-01"), as.Date("2024-09-30"), by = "day")
set.seed(42)
tmin <- rnorm(length(dates), mean = 12, sd = 3)
tmax <- tmin + runif(length(dates), 8, 15)
ck_huglin(tmin, tmax, dates, lat = 45)
#> period value index unit
#> 1 2024-01-01 1976.338 huglin degree-days