This function calculates growing degree days (GDD) using the average of the daily maximum and minimum temperatures, a base temperature and a maximum base temperature
gdd(tmax, tmin, tbase, tbase_max, type = "C")daily maximum temperature
daily minimum temperature
base temperature
maximum base temperature
either "B", "C", or "D". The default is "C". Type "B" - The heat units are calculated based on the difference between the mean daily temperature and the threshold (`tbase`). In the case when the value of `tmin` is lower than `tbase`, then it is replaced by `tbase`. Type `"C"` - same as type `"B"` and when the value of `tmax` is larger than `tbase_max`, then it is replaced by `tbase_max`. Type `"D"`- same as type `"B"` and when the value of `tmax` is larger than `tbase_max`, then no heat units are added.
a numeric vector with GDD values
Baskerville, G., & Emin, P. (1969). Rapid Estimation of Heat Accumulation from Maximum and Minimum Temperatures. Ecology, 50(3), 514-517. doi:10.2307/1933912
[base_temp()] for determining a base temperature
set.seed(25)
df <- data.frame(tmax = runif(100, 6, 10), tmin = runif(100, 4, 6))
gdd(tmax = df$tmax, tmin = df$tmin, tbase = 5, tbase_max = 30)
#> [1] 1.392985 3.282512 4.259733 6.554503 7.303287 9.810031
#> [7] 11.562224 12.765263 13.878573 15.000558 16.156492 17.383517
#> [13] 19.800607 21.478356 23.369211 24.164222 26.150454 28.305062
#> [19] 29.758898 31.717690 32.299061 33.700871 34.404637 35.213010
#> [25] 36.296748 37.764013 38.409299 40.410950 42.352622 43.437435
#> [31] 45.583809 46.898344 47.871860 48.918490 51.504291 52.812050
#> [37] 55.232033 56.759521 57.572129 58.319572 60.705153 62.204334
#> [43] 63.838365 65.826710 67.450093 68.534809 71.016913 73.127310
#> [49] 74.131668 76.074927 76.844723 78.817516 80.960568 82.446401
#> [55] 84.000869 84.975839 85.778519 87.371530 88.238972 89.469210
#> [61] 90.638672 91.785048 92.894984 94.750790 96.491373 98.958947
#> [67] 100.404830 102.695104 104.531536 105.704549 108.122525 108.897840
#> [73] 109.647810 112.055520 113.011545 114.644393 115.422643 118.031517
#> [79] 118.893385 119.761111 121.831796 123.021970 125.019018 125.635943
#> [85] 127.751313 129.805915 130.925935 132.390394 134.460273 136.077224
#> [91] 137.989401 138.928684 140.986772 142.896909 143.415940 144.949065
#> [97] 146.758733 149.065694 150.026993 151.204477