Skip to contents

Extract TerraClimate variables (monthly) from Google Earth Engine

Source: R/l4h_terra_climate.R
l4h_terra_climate.Rd

Extracts one or more TerraClimate variables for a user-defined region and time range from the Earth Engine dataset IDAHO_EPSCOR/TERRACLIMATE. The function summarizes each monthly image over the region using a chosen statistic (e.g., mean/median), applies the appropriate scale factors to return values in native units, and returns an sf or tibble.

[Experimental]

Usage

l4h_terra_climate(
  from,
  to,
  band,
  region,
  scale = 1000,
  stat = "mean",
  sf = TRUE,
  quiet = FALSE,
  force = TRUE,
  ...
)

Arguments

from

Character or Date. Start date ("YYYY-MM-DD").

to

Character or Date. End date ("YYYY-MM-DD").

band

Character vector. One or more TerraClimate variables to extract. Supported codes: "aet", "def", "pdsi", "pet", "pr", "ro", "soil", "srad", "swe", "tmmn", "tmmx", "vap", "vpd", "vs". Scale factors and units (aplicadas automáticamente):

  • aet (mm, ×0.1), def (mm, ×0.1), pdsi (unitless, ×0.01),

  • pet (mm, ×0.1), pr (mm, ×1), ro (mm, ×1), soil (mm, ×0.1),

  • srad (W/m², ×0.1), swe (mm, ×1),

  • tmmn (°C, ×0.1), tmmx (°C, ×0.1),

  • vap (kPa, ×0.001), vpd (kPa, ×0.01), vs (m/s, ×0.01).

region

Spatial object defining the region of interest. Accepts an sf, sfc, or SpatVector object.

scale

Numeric. Reducer scale in meters. Default 1000. (TerraClimate pixel ≈ 4638 m; usar ~4500–5000 m suele ser adecuado.)

stat

Character. Summary statistic per image per region. One of "mean", "median", "min", "max". Passed internally to the extractor.

sf

Logical. If TRUE, returns an sf; if FALSE, returns a tibble. Default TRUE.

quiet

Logical. If TRUE, suppresses progress bars/messages. Default FALSE.

force

Logical. If TRUE, fuerza la extracción aun si hay caché. Default TRUE.

...

Additional arguments passed to the extraction backend.

Value

An sf or tibble with columns:

  • date (Date, primer día del mes),

  • variable (character, código TerraClimate),

  • value (numérico, en unidades nativas ya escaladas), plus geometry if sf = TRUE, and any attributes from region.

Credits

Pioneering geospatial health analytics and open‐science tools. Developed by the Innovalab Team, for more information send a email to imt.innovlab@oficinas-upch.pe

Follow us on :

References

Abatzoglou, J. T., Dobrowski, S. Z., Parks, S. A., & Hegewisch, K. C. (2018). TerraClimate, a high-resolution global dataset of monthly climate and climatic water balance from 1958–2015. Scientific Data, 5, 170191. doi:10.1038/sdata.2017.191

Examples

if (FALSE) { # \dontrun{
library(sf)
library(land4health)
rgee::ee_Initialize()

# ROI simple (EPSG:4326)
region <- st_as_sf(st_sfc(
  st_polygon(list(matrix(c(
    -74.1, -4.4,
    -74.1, -3.7,
    -73.2, -3.7,
    -73.2, -4.4,
    -74.1, -4.4
  ), ncol = 2, byrow = TRUE))), crs = 4326))

# Precipitación mensual (mm) 2020, promedio espacial
out_pr <- l4h_terra_climate(
  from = "2020-01-01",
  to   = "2020-12-31",
  band = "pr",
  region = region,
  stat = "mean",
  scale = 5000
)
head(out_pr)

# Múltiples variables: Tmax (°C) + VPD (kPa)
out_multi <- l4h_terra_climate(
  from = "2019-01-01",
  to   = "2019-12-31",
  band = c("tmmx","vpd"),
  region = region,
  stat = "median",
  scale = 5000
)
} # }