predFAO: Predict the minimum temperature using the recommended FAO...
In frost: Prediction of Minimum Temperature for Frost Forecasting in Agriculture

Description Usage Arguments Details Value Examples

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).

1	predFAO(model, t, dw = NULL)

`model`	: a FAOFrostModel object
`t`	[<c2><b0>C]: an array of ambient temperature, two hours after sunset.
`dw`	[<c2><b0>C]: an array of dew points, two hours after sunset, by default is NULL.

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>

tmin [<c2><b0>C]: minimum temperature

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," <c2><b0>C")