Extract CHIRPS v3 precipitation data from Google Earth Engine

Extracts CHIRPS v3 precipitation estimates for a user-defined region and time range from the Earth Engine dataset UCSB-CHC/CHIRPS/V3/DAILY_SAT (IMERG-based) or UCSB-CHC/CHIRPS/V3/DAILY_RNL (ERA5-based). The function supports daily, monthly, and annual temporal aggregation. Monthly and annual values are computed as sums of daily precipitation (mm), which is the standard in hydrology and vector-borne disease modelling.

CHIRPS v3 (Climate Hazards Center InfraRed Precipitation with Stations version 3) is a quasi-global (60°S–60°N), high-resolution (0.05°) gridded rainfall dataset from 1981 to near-present, combining satellite thermal infrared estimates with in-situ station observations.

Usage

l4h_chirps(
  from,
  to,
  by = "month",
  product = "sat",
  region,
  scale = 5566,
  stat = "mean",
  sf = TRUE,
  quiet = FALSE,
  force = FALSE,
  ...
)

Arguments

from

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

to

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

by

Character. Temporal aggregation frequency. Options:

• "daily" — daily precipitation (mm/day),

• "month" — monthly accumulated precipitation (mm/month),

• "annual" — annual accumulated precipitation (mm/year). Default "month".

product

Character. CHIRPS v3 daily product used for disaggregation. Options:

• "sat" — IMERG-based daily (0.1° resolution, available from 2001),

• "rnl" — ERA5-based daily (0.25° resolution, available from 1981). Default "sat".

region

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

scale

Numeric. Reducer scale in meters. Default 5566 (CHIRPS native pixel ~5,566 m).

stat

Character. Summary statistic per image per region. One of "mean", "median", "min", "max".

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, skips the representativity check. Default FALSE.

...

Additional arguments passed to the extraction backend.

Value

An sf or tibble with columns:

• date (Date — first day of the period),

• variable (character — "precipitation"),

• value (numeric — mm in the corresponding time unit), 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 an email to imt.innovlab@oficinas-upch.pe.

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References

Funk, C., Peterson, P., Harrison, L. et al. (2026). The Climate Hazards Center Infrared Precipitation with Stations, Version 3. Scientific Data, 13, 718. doi:10.1038/s41597-026-07096-4

Examples

# \donttest{
if (interactive()) {
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))

# 1. Monthly precipitation (mm/month) 2020, SAT product
out_monthly <- l4h_chirps(
  from    = "2020-01-01",
  to      = "2020-12-31",
  by      = "month",
  product = "sat",
  region  = region,
  stat    = "mean"
)
head(out_monthly)

# 2. Annual precipitation (mm/year) 2015-2020, RNL product
out_annual <- l4h_chirps(
  from    = "2015-01-01",
  to      = "2020-12-31",
  by      = "annual",
  product = "rnl",
  region  = region,
  stat    = "mean"
)
head(out_annual)

# 3. Daily precipitation (mm/day) for one month
out_daily <- l4h_chirps(
  from    = "2020-06-01",
  to      = "2020-06-30",
  by      = "daily",
  product = "sat",
  region  = region,
  stat    = "mean"
)
head(out_daily)
}
# }