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Download and process evapotranspiration data

Source: R/l4h_sebal_modis.R
l4h_sebal_modis.Rd

This function accesses the geeSEBAL-MODIS collection published by the ET-Brasil project, extracts the etp band (daily evapotranspiration in mm/day), and allows temporal aggregation by 8-day images or monthly or yearly composites period. Optionally, results can be returned as sf/tibble objects in R.

[Stable]

Usage

l4h_sebal_modis(
  from,
  to,
  by = "8 days",
  region,
  fun = "mean",
  sf = TRUE,
  force = FALSE,
  quiet = FALSE,
  ...
)

Arguments

from

Start date in "YYYY-MM-DD" format.

to

End date in "YYYY-MM-DD" format.

by

Temporal aggregation frequency. Options: "8 days" (original 8-day composites), "month" (monthly average or sum), or "annual" (annual avergae or sumperiod).

region

A spatial object defining the region of interest. Accepts sf, SpatVector, or ee$FeatureCollection objects.

fun

Aggregation function when by = "month" or "total". Valid values are "mean" or "sum".

sf

Logical. Return result as an sf object? Default is TRUE.

force

Logical. If TRUE, forces download even if a local file already exists.

quiet

Logical. If TRUE, suppress the progress bar (default FALSE).

...

arguments of ee_extract of rgee packages.

Value

A sf or tibble object with etp values.

References

  • Comini, B., Ruhoff, A., Laipelt, L., Fleischmann, A., Huntington, J., Morton, C., Melton, F., Erickson, T., Roberti, D., Souza, V., Biudes, M., Machado, N., Santos, C. & Cosio, E. (2023). geeSEBAL‑MODIS: Continental‑scale evapotranspiration based on the surface energy balance for South America. Preprint. DOI: 10.13140/RG.2.2.17579.11041

  • geeSEBAL‑MODIS v0‑02 dataset. Licensed under the Creative Commons Attribution 4.0 International (CC‑BY‑4.0) license.

Examples

if (FALSE) { # \dontrun{
## Assume `my_roi` is an sf polygon covering your area of interest.
## 1. Eight-day composites (8 days)
##    2020-01-01 → 2020-12-31, reducer = "mean"
sebal_8d <- l4h_sebal_modis(
  from   = "2020-01-01",
  to     = "2020-12-31",
  region = my_roi
)

## 2. Monthly means
##    Same period, but aggregated to calendar months
sebal_month <- l4h_sebal_modis(
  from   = "2020-01-01",
  to     = "2020-12-31",
  by     = "month",
  region = my_roi
)

## 3. Annual evapotranspiration
##    2015 → 2023, one value per year
sebal_annual <- l4h_sebal_modis(
  from   = 2015,
  to     = 2023,
  by     = "annual",
  fun    = "sum",
  region = my_roi,
  sf     = FALSE
)
} # }