mc_calc_fdd {myClim}

Freezing Degree Days

Description

This function creates a new virtual sensor on locality within the myClim data object. The new virtual sensor provides FDD Freezing Degree Days.

Usage

mc_calc_fdd(data, sensor, output_prefix = "FDD", t_base = 0, localities = NULL)

Arguments

data

cleaned myClim object see myClim-package

sensor

name of temperature sensor used for FDD calculation e.g. TMS_T3 see names(mc_data_sensors)

output_prefix

name prefix of new FDD sensor (default "FDD")

name of output sensor consists of output_prefix and value t_base (FDD0_TMS_T3)

t_base

threshold temperature for FDD calculation (default 0)

localities

list of locality_ids for calculation; if NULL then all (default NULL)

Details

The allowed step length for FDD calculation is day and shorter. Function creates a new virtual sensor with the same time step as input data. For shorter time steps than the day (which is however not intuitive for FDD) the FDD value is the contribution of the time step to the freezing degree day. Be careful while aggregating freezing degree days to longer periods only meaningful aggregation function is sum, but myClim allows you to apply anything see mc_agg().

Note that FDD is always positive number, despite summing freezing events. When you set t_base=-1 you get the sum of degree days below -1 °C but expressed in positive number if you set t_base=1 you get also positive number. Therefore pay attention to name of output variable which contains t_base value. FDD1_TMS_T3, t_base=1 vs FDDminus1_TMS_T3, t_base=-1

Value

The same myClim object as input but with added virtual FDD sensor

Examples

fdd_data <- mc_calc_fdd(mc_data_example_agg, "TMS_T3", localities = c("A2E32", "A6W79"))
fdd_agg <- mc_agg(fdd_data, list(TMS_T3=c("min", "max"), FDD5="sum"), period="day")