Read gridded LPJmL-forcing windspeed onto WHEP's grid.

Reads the GSWP3-W5E5 monthly windspeed forcing used to drive LPJmL (single consolidated NetCDF, already on WHEP's native 0.5-degree grid) and returns it in tidy long form. The file's wind variable carries no units attribute, because the monthly aggregation dropped it; the unit is metres per second, taken from the ISIMIP2a GSWP3-W5E5 daily source the file is derived from, which declares units = "m s-1" and standard_name = "wind_speed". That is why the output column is named windspeed_ms.

The windspeed_ms column is named to match the MANNER driver column of the same name, so the output feeds calculate_nh3() (method = "manner" or "manner_default", whose organic path requires windspeed_ms) after a join onto the gridded N-input records; this reader is the package's only source of that driver.

Usage

read_lpjml_wind(years = NULL, wind_dir = NULL, example = FALSE)

Arguments

years

Optional integer vector of calendar years to keep. NULL reads every year present in the file (1901-2019 in the currently pinned base; the span is whatever the resolved file holds, not a fixed range).

wind_dir

Path to the directory holding a wind_gswp3-w5e5_<span>_monthly.nc. The span in that filename is resolved against the directory rather than assumed, so an extended base reads without a code change. Defaults to Sys.getenv("WHEP_WIND_DIR"); when that is also unset, the registered lpjml-wind-isimip-1901-2019 pin is read via whep_read_file().

example

If TRUE, return a small fixture instead of reading data. Defaults to FALSE.

Value

A tibble with lon, lat, year, month, windspeed_ms.

See also

calculate_nh3(), which consumes windspeed_ms.

Examples

read_lpjml_wind(example = TRUE)
#> # A tibble: 1 × 5
#>     lon   lat  year month windspeed_ms
#>   <dbl> <dbl> <int> <int>        <dbl>
#> 1 -180.  89.8  1901     1          3.2