temperature_scenario_from_records {chillR}

Make monthly temperature scenario from historic records

Description

Produces a list of scenarios containing monthly means for Tmin and Tmax that are representative of particular years. These scenario are computed by applying linear regression to a file containing Tmin and Tmax records, and using the regression model to calculate typical values for the user-specified years.

Usage

temperature_scenario_from_records(
  weather,
  year,
  weather_start = NA,
  weather_end = NA,
  scen_type = "running_mean",
  runn_mean = 15
)

Arguments

weather

daily weather, as produced with the fix_weather function. Can also be generated by other means, but shouold contain the columns c("Month","Day","Year","Tmin","Tmax").

year

numeric vector of years, for which the scenario is to be produced.

weather_start

start year of the period to be considered in calculating the regression. Defaults to NA, which means the first year of the record is used as start year.

weather_end

end year of the period to be considered in calculating the regression. Defaults to NA, which means the last year of the record is used as end year.

scen_type

character string, either "regression" or "running_mean", specifying how the scenario should be produced. "regression" computed the scenario based on an assumed linear trend in the data; "running_mean" uses a running mean function instead, with the length of the running mean window determined by the runn_mean parameter. The default is a running mean function, since the assumption of a linear trend often does not hold.

runn_mean

number of vector elements to use for calculating the running mean; this is reduced, if the time series is not long enough to accommodate the specified window. Defaults to 15.

Details

This function produces outputs that can be used as input for the temperature_generation function. Sample applications are the use of the temperature_generation function for making replicate weather records for a given year for risk assessment purposes, or the generation of a weather scenario that can be compared with other datasets (e.g. climate scenarios based on the WorldClim dataset refer to a 1951-2000 baseline, so that meaningful use of such scenarios for local contexts requires consideration of a scenario that corresponds to temperatures in 1975, the central year of this period).

Value

list of climate scenario objects, consisting of the following elements: 'data' = a data frame with n_intervals elements containing the absolute temperature information. 'scenario_year' = the year the scenario is representative of, i.e. the specified 'year' parameter. 'reference_year' = NA (because this is an absolute temperature scenarios, not a relative one); 'scenario_type' = 'absolute' (because this is an absolute temperature scenario, not a relative one); 'labels' = 'regression-based scenario'.

Author(s)

Eike Luedeling

Examples

temperature_scenario_from_records(weather=KA_weather,year=2001,weather_start=2000,weather_end=2005)