Predict the minimum temperature using the recommended FAO equation, which can be applied to nights with radiative frost (wind less than 2 m/s^2, no clouds, no fog, no rain).
predFAO(model, t, dw = NULL)
| model | : a FAOFrostModel object |
|---|---|
| t | [°C]: an array of ambient temperature, two hours after sunset. |
| dw | [°C]: an array of dew points, two hours after sunset, by default is NULL. |
tmin [°C]: minimum temperature
The method was extracted from the documentation and previous implementation in FFST.xls file, which is name in the book "Frost Protection: fundamentals, practice, and economics. Volume 1. Authors: Richard L Snyder, J. Paulo de Melo-Abreu. Food and Agriculture Organization of the United Nations. 2005"
This function returns Tmim = a * temp + b * dew + c if dew argument is not null. Otherwise, return Tmin = a * temp + c, if dew is NULL.
For more details please check: <http://www.fao.org/docrep/008/y7223e/y7223e0b.htm#bm11.8> <http://www.fao.org/docrep/008/y7223e/y7223e0b.htm> FFST spreasheet <http://biomet.ucdavis.edu/frostprotection/FTrend/FFST_FTrend.htm>
t0 <- c(3.2,0.8,0.2,2.6,4.4,5.2,2.7,1.2,4.5,5.6) # temperature 2 hours after sunset td <- c(-4.2,-8.8,-6.5,-6.2,-6.1,2.6,-0.7,-1.7,-1.2,0.1) # dew point 2 hours after sunset tn <- c(-3.1,-5,-6.3,-5.4,-4,-2.5,-4.8,-5,-4.4,-3.3) out <- buildFAO(dw = td,temp=t0,tmin=tn) current_temp <- 10 current_dw <- 2 ptmin <- predFAO(out,current_temp,current_dw) cat("The predicte minimum temperature is ",ptmin," °C")#> The predicte minimum temperature is -0.7409219 °C