evapoRe (version 1.0.1)

calc_u2: Calculate Wind Speed at 2 Meters (u2)

Description

Computes wind speed at 2 meters (u2) based on wind speed measured at a different height (`z_u`).

Usage

calc_u2(x, z_u = 10)
# S4 method for Raster
calc_u2(x, z_u = 10)
# S4 method for character
calc_u2(x, z_u = 10)
# S4 method for data.table
calc_u2(x, z_u = 10)

Value

Wind speed adjusted to 2 meters, returned as:

• A `RasterBrick`, if input is a raster object or file path.

• A `data.table` with updated `"value"` column, if input is a `data.table`.

Arguments

x

A `Raster*` object, a file path (`character`) to a raster file, or a `data.table` containing wind speed data.

z_u

Measurement height (m) of the provided wind speed. Default is 10.

Details

For raster inputs, provide a `Raster*` object or file path (`character`) for wind speed at height `z_u`. For `data.table` input, provide a single `data.table` with columns: `"lon"`, `"lat"`, `"date"`, and `"value"`, where `"value"` contains wind speeds at height `z_u`.

If `z_u` is 2, the function returns the input unchanged.

Examples

# \donttest{
# Raster input
if (requireNamespace("raster", quietly = TRUE)) {
  wind_path <- file.path(tempdir(), "wind_speed.nc")

  if (file.exists(wind_path)) {
    dummie_u <- raster::brick(wind_path)
    u2_raster <- calc_u2(dummie_u, z_u = 10)
  }
}

# File path input
wind_path <- file.path(tempdir(), "wind_speed.nc")
if (file.exists(wind_path)) {
  u2_from_file <- calc_u2(wind_path, z_u = 10)
}

# data.table input
if (requireNamespace("data.table", quietly = TRUE)) {
  dt <- data.table::data.table(
    lon = c(10.0, 10.5),
    lat = c(45.0, 45.5),
    date = as.Date(c("2001-06-01", "2001-06-02")),
    value = c(3.5, 4.1)
  )
  u2_dt <- calc_u2(dt, z_u = 10)
}
# }