FFD: Frost-Free Day Evaluation

In sharpshootR: A Soil Survey Toolkit

Frost-Free Day Evaluation

Description

Evaluation frost-free days and related metrics from daily climate records.

Usage

FFD(
  d,
  returnDailyPr = TRUE,
  minDays = 165,
  frostTemp = 32,
  endSpringDOY = 182,
  startFallDOY = 213
)

Arguments

d	data.frame with columns 'datetime' 'year', and 'value'; 'value' being daily minimum temperature, see details
returnDailyPr	optionally return list with daily summaries
minDays	min number of days of non-NA data in spring | fall, required for a reasonable estimate of FFD
frostTemp	critical temperature that defines "frost" (same units as d$value)
endSpringDOY	day of year that marks end of "spring" (typically Jan 1 – June 30)
startFallDOY	day of year that marks start of "fall" (typically Aug 1 – Dec 31)

Details

The default frostTemp=32 is suitable for use with minimum daily temperatures in degrees Fahrenheit. Use frostTemp = 0 for temperatures in degrees Celsius.

FFD tutorial

Value

a data.frame when a returnDailyPr=FALSE, otherwise a list with the following elements:

• summary: FFD summary statistics as a data.frame

• fm: frost matrix

• Pr.frost: Pr(frost|day): daily probability of frost

Author(s)

D.E. Beaudette

Examples

# 11 years of data from highland meadows
data('HHM', package = 'sharpshootR')
x.ffd <- FFD(HHM, returnDailyPr = FALSE, frostTemp = 32)

str(x.ffd)

sharpshootR documentation built on Aug. 24, 2023, 5:07 p.m.