Skip to contents

Read EMEP MSC-W atmospheric nitrogen deposition onto WHEP's grid.

Source: R/n_deposition_emep.R
read_emep_deposition.Rd

Reads the yearly EMEP MSC-W model results (EMEP01 rv5.6, 2025 reporting round) for one nitrogen species and aggregates the 0.1-degree grid to WHEP's 0.5-degree grid. NHx is DDEP_RDN_m2Grid + WDEP_RDN and NOy is DDEP_OXN_m2Grid + WDEP_OXN, dry plus wet. The source is a density (mgN/m2 over the whole grid cell), so it is converted to kg N/ha (x 0.01) and aggregated by plain mean: the 0.1-degree grid nests exactly 5x5 inside each 0.5-degree block and the cell area varies by under 0.2 per mille inside a block.

EMEP is the reference correct_n_deposition() corrects HaNi's European trend toward. It is a regional product (domain lon -30 to 90, lat 30 to 82) and is not a substitute for HaNi anywhere else.

The files are third-party model output and are read from local disk: inst/scripts/download/download_emep.R fetches them from the Norwegian Meteorological Institute THREDDS server into <dest_dir>/EMEP/, and WHEP_EMEP_DIR points there.

Simpson, D. et al. (2012). The EMEP MSC-W chemical transport model – technical description. Atmospheric Chemistry and Physics 12(16), 7825-7865. doi:10.5194/acp-12-7825-2012

Usage

read_emep_deposition(
  species = c("nhx", "noy"),
  emep_dir = NULL,
  years = NULL,
  example = FALSE
)

Arguments

species

Which species to read, "nhx" or "noy".

emep_dir

Path to the directory holding the yearly EMEP files. Defaults to Sys.getenv("WHEP_EMEP_DIR").

years

Optional integer vector of calendar years to read. NULL reads every year with a file in emep_dir. A requested year with no file is not read; the years actually returned are the ones in the output.

example

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

Value

A tibble with lon, lat, year and deposition_kgn_ha (the species' grid-mean deposition rate over the whole 0.5-degree cell).

Examples

read_emep_deposition(example = TRUE)
#> # A tibble: 1 × 4
#>     lon   lat  year deposition_kgn_ha
#>   <dbl> <dbl> <int>             <dbl>
#> 1 -0.25 -0.25  2020               1.1