calculate_eurocordex_relative_humidity: calculate relative humidity from specific humidity,...

In neumannd/eurocordex2swatTools: Tools to read in EURO-CORDEX Data and to write them out into SWAT version 2012 input files

Description

The relative humidity was missing in some archived simulations. In these cases, it can be approximately calculated from the specific humidity, temperature, and pressure. This is done by this funciton. It uses 'read_eurocordex_data' to obtain the data of the three needed variables.

Usage

calculate_eurocordex_relative_humidity(dir, domain, driver, experiment,
  ensemble, institute, model, downscaling_realisation, time_frequency, time,
  stations)

Arguments

dir	string: file direcotory
domain	string: model domain, see EURO-CORDEX Doc
driver	string: driving global model, see EURO-CORDEX Doc
experiment	string: experiment type (historical, rcp2.6, rcp4.5, rcp8.5), see EURO-CORDEX Doc
ensemble	string: ensemble (e.g. r12i1p1), see EURO-CORDEX Doc
institute	string: institution who did the model run, see EURO-CORDEX Doc
model	string: used RCM (regional climate model), see EURO-CORDEX Doc
downscaling_realisation	string: version of the downscaling realisation (most often 'v1'), see EURO-CORDEX Doc
time_frequency	string: time frequency of model output (e.g. 'day'), see EURO-CORDEX Doc
stations	data.frame of three columns station_name, lon, and lat
time_lim	string, numeric or integer: array of length 2 containing start and end time to read in format 'YYYYMMDD' (as character, numeric or integer)

Details

The relative humidity was missing in some archived simulations. In these cases, it can be approximately calculated from the specific humidity, temperature, and pressure. This is done by this funciton. It uses 'read_eurocordex_data' to obtain the data of the three needed variables.

The relative humidity is calculated given in the equation below. The '=' is actually an 'approximately'.

hurs = 0.263 Pa^{-1} huss * ps * exp(-17.67 * (tas - 273.16 K)/(tas - 29.65 K))

with specific humidity (huss, dimensionless), pressure (ps in Pa), and temperature (tas in K).

Value

data.frame imported data

Examples

# define directory that contains the model data
dir <- '/my/data/directory/for/EUROCORDEX/data'

# define EURO-CORDEX model run details
domain <- 'EUR-11'
driver <- 'ICHEC-EC-EARTH'
experiment <- 'rcp85'
ensemble <- 'r12i1p1'
institute <- 'CLMcom'
model <- 'CCLM4-8-17'
downscaling_realisation <- 'v1'
time_frequency <- 'day'
time <- c('20110201', '20170301')

# define stations
stations <- data.frame(c('abc', 'def', 'ghi', 'jkl'), c(10.31, 11.12, 9.2, 9.31), c(55.19, 54.77, 55.02, 53.2), c(44, 1, 5, 107), stringsAsFactors = FALSE)
names(stations) <- c('station_name', 'lon', 'lat', 'elev')

# read in the data
my_data <- calculate_eurocordex_relative_humidity(dir, domain, driver, experiment, ensemble, institute, model, downscaling_realisation, time_frequency, time, stations)


# have a look into the README for further details

neumannd/eurocordex2swatTools documentation built on May 14, 2019, 2:17 p.m.