This function calculates winter chill for temperate trees according to the Chilling Hours Model.
Chilling_Hours(HourTemp, summ = TRUE)
Vector of hourly temperatures.
Boolean parameter indicating whether calculated metrics should be provided as cumulative values over the entire record (TRUE) or as the actual accumulation for each hour (FALSE).
Chilling Hours are calculated as suggested by Bennett (1949) (all hours with temperatures between 0 and 7.2 degrees C are considered as one Chilling Hour.
Vector of length length(HourTemp) containing the cumulative Chilling Hours over the entire duration of HourTemp.
After doing extensive model comparisons, and reviewing a lot of relevant literature, I do not recommend using the Chilling Hours, especially in warm climates! The Dynamic Model (Chill Portions), though far from perfect, seems much more reliable.
Chilling Hours references:
Weinberger JH (1950) Chilling requirements of peach varieties. Proc Am Soc Hortic Sci 56, 122-128
Bennett JP (1949) Temperature and bud rest period. Calif Agric 3 (11), 9+12
weather<-fix_weather(KA_weather[which(KA_weather$Year>2006),]) hourtemps<-stack_hourly_temps(weather,latitude=50.4) Chilling_Hours(hourtemps$hourtemps$Temp)
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