degree_days: Caclulate degree days

In johnwoodill/nonlineartempr: Calculate daily degree days and time in each degree

Description

degree_days returns a data frame with calculated daily degree days within a specified thresholds.

Usage

degree_days(data, thresholds)

Arguments

data	data in wide format with minimum temperature labeled as tmin and maximum temperature labeled as tmax
thresholds	threshold of temperature intervals to calculate degree days

Details

To generate degree days the data must be in wide format with minimum temperature column labeled as tmin and maximum temperature labeled as tmax.

Degree days are calcuated from the following cases:

(1) Minimum temperature >= threshold

dday = (tmax - tmin/2) - threshold

(2) Minimum temperature < Threshold < Maximum Temperature

dday = ( W integral_theta^pi/2 sin(t)dt - integral_theta^pi/2 (threshold - tmin)dt ) / pi

W = (tmax - tmin)/2

theta = sin^-1 [ ( tmax - tmin )/W ]

(3) Otherwise, degree days = 0

References

Snyder, Richard L. "Hand calculating degree days." Agricultural and forest meteorology 35, no. 1-4 (1985): 353-358.

Woodill, A. John "United States Temperature Exposure 1900-2013." (2016) http://johnwoodill.blogspot.com/2016/06/us-degree-days-heat-map-interesting.html

Examples

data(napa)
degree_days(napa, thresholds = c(0:35))

johnwoodill/nonlineartempr documentation built on Dec. 7, 2019, 9:11 a.m.