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Read a CRU TS 4.09 monthly climate variable into a tidy tibble.

Source: R/cru_climate.R
read_cru_climate.Rd

Reads one monthly variable of the CRU TS 4.09 high-resolution gridded climate dataset (1901-2024, global 0.5 degree) from its NetCDF file and returns it in tidy long form, one row per land cell-month. Requested years are sliced at read time so the full grid is never materialised, and ocean fill cells are dropped. Values are returned in the file's native units (not converted): tmp/tmn/tmx/dtr in degrees Celsius, pre in mm/month, pet in mm/day, vap in hPa, cld in percent, wet and frs in days.

Usage

read_cru_climate(
  var = c("tmp", "pet", "pre", "tmn", "tmx", "vap", "cld", "wet", "dtr", "frs"),
  years = NULL,
  cru_dir = NULL,
  data = NULL,
  example = FALSE
)

Source

CRU TS 4.09 (Climatic Research Unit, University of East Anglia; Harris, Osborn & Jones 2020, Scientific Data, doi:10.1038/s41597-020-0453-3 ).

Arguments

var

Variable name, one of "tmp", "pet", "pre", "tmn", "tmx", "vap", "cld", "wet", "dtr" or "frs".

years

Optional integer vector of calendar years to keep. NULL keeps every year present in the file.

cru_dir

Path to the CRU TS NetCDF directory. Defaults to Sys.getenv("WHEP_CRU_DIR"); aborts when neither is set.

data

Optional pre-read tibble (lon, lat, year, month, value) used in place of reading NetCDF, for testing.

example

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

Value

A tibble with columns lon, lat, year, month, value (native units) and var (the requested variable name).

Examples

read_cru_climate(example = TRUE)
#> # A tibble: 10 × 6
#>       lon    lat  year month value var  
#>     <dbl>  <dbl> <int> <int> <dbl> <chr>
#>  1  22.8  -31.2   2000     7   8.6 tmp  
#>  2  49.2  -14.2   2000     1  20.8 tmp  
#>  3 110.     1.25  2000     1  26.2 tmp  
#>  4  57.2   25.8   2000     1  20.7 tmp  
#>  5  -1.75  27.2   2000     1  12.7 tmp  
#>  6  68.2   27.2   2000     1  16.2 tmp  
#>  7 -92.8   38.8   2000     1  -0.1 tmp  
#>  8  42.2   58.8   2000     7  19   tmp  
#>  9  18.8   66.2   2000     7  13   tmp  
#> 10  80.8   72.8   2000     7   5.6 tmp