| chilldate {springpheno} | R Documentation |
Chill Date Calculator
Description
This function calculates the estimated day of the calendar year where the chill requirement is met for each of the three plants used in the extended spring indices (SI-x, Schwarz et al. 2006; 2013).
Usage
chilldate(tasmax, tasmin, DOY, daylen, baset, plant = 1)
Arguments
tasmax |
Vector - daily high temperatures for a given year |
tasmin |
Vector - daily low temperatures for a given year |
DOY |
Vector - day of year values for a given year (1:365 or 1:366 depending on calendar) |
daylen |
Vector - day lengths for each day for a given year (calculated from daylength function). |
baset |
Scalar - base temperature for determining chill hours. Typically this is 44.96 degrees Fahrenheit, but can be plant specific. |
plant |
Plant type 1 (default), 2, or 3. plant = 1 for lilac, plant = 2 for arnold red, or plant =3 for zabelli. |
Value
chillDOY - scalar, estimated day of year the chill requirement for the specified plant is met.
Note
Many questions regarding how this is calculated, use this function at your own risk.
Author(s)
Adrienne M. Wootten (University of Oklahoma)
References
Schwarz, M., R. Ahas and A. Aasa, 2006: Onset of spring starting earlier across the Northern Hemisphere, 12, DOI: 10.1111/j.1365-2486.2005.01097.x
Schwarz, M., T.R. Ault and J.L. Betancourt, 2013: Spring onset variations and trends in the continental United States: Past and regional assessment using temperature-based indices. International Journal of Climatology, 33, DOI: 10.1002/joc.3625