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Download and process NASA POWER daily climate data

Source: R/download_process_nasapower.R
download_process_nasapower.Rd

Downloads daily climate variables from the NASA POWER API for representative administrative units, processes them into daily and monthly datasets, and generates data dictionaries for each output.

Usage

download_process_nasapower(
  adm_sf,
  admin_cols = c("adm0", "adm1", "adm2"),
  start_date = "2025-01-01",
  end_date = "2025-12-31",
  power_vars = c("PRECTOTCORR", "T2M_MAX", "T2M_MIN", "T2M", "TS", "TS_MAX", "TS_MIN",
    "RH2M", "T2MDEW"),
  power_community = "ag",
  max_retries = 3,
  dict_language = "fr"
)

Arguments

adm_sf

An sf object containing administrative polygons. Must include columns specified in admin_cols and have a valid CRS.

admin_cols

Character vector of administrative identifier columns, ordered from highest to lowest level. The last column is treated as the unit identifier. Default is c("adm0", "adm1", "adm2").

start_date

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

end_date

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

power_vars

Character vector of NASA POWER variable codes to download. Drop a code to exclude that variable from the outputs; add a code to opt in. Codes recognised by the rename map (clean column name in parentheses): PRECTOTCORR (rainfall_mm), T2M (air_temperature_c), T2M_MAX/T2M_MIN (max/min_air_temperature_c), TS (land_temperature_c), TS_MAX/TS_MIN (max/min_land_temperature_c), RH2M (humidity_pct), T2MDEW (dewpoint_c), T2MWET (wet_bulb_temperature_c), QV2M (specific_humidity_gkg), PS (surface_pressure_kpa), WS2M/WS2M_MAX/WS2M_MIN (wind_speed_ms), ALLSKY_SFC_SW_DWN (solar_radiation_kwhm2), CLOUD_AMT (cloud_amount_pct), GWETTOP (surface_soil_wetness), GWETROOT (root_soil_wetness), GWETPROF (profile_soil_wetness). Unrecognised codes are downloaded but dropped from the cleaned daily/monthly outputs.

power_community

NASA POWER community parameter. Default is "ag" (agroclimatology).

max_retries

Maximum retry attempts per unit. Default is 3.

dict_language

Language for data dictionaries. Default is "fr".

Value

A list with four elements:

daily

Tibble of daily climate data with admin columns plus an elevation_m column (MERRA-2 grid-cell elevation, static per polygon, parsed from the POWER response metadata).

monthly

Tibble of monthly aggregated climate data. For each requested variable: mean_, median_, min_, max_ versions; rainfall additionally gets total_. elevation_m is carried through as a static column.

dict_daily

Data dictionary for daily data

dict_monthly

Data dictionary for monthly data

Details

For each polygon, a single representative point (centroid) is used to download data. Returned values correspond to NASA POWER grid-cell averages (approximately 0.5 degree resolution) and should be interpreted as regional conditions rather than point measurements.

The function is robust to partial download failures. Administrative units that fail to download after the specified number of retries are skipped with a warning. Execution stops only if no units return data.

Examples

if (FALSE) { # \dontrun{
# load administrative boundaries
adm_sf <- sf::st_read("path/to/admin_boundaries.shp")

# download NASA POWER data for 2024
result <- download_process_nasapower(
  adm_sf = adm_sf,
  admin_cols = c("adm0", "adm1", "adm2"),
  start_date = "2024-01-01",
  end_date = "2024-12-31"
)

# access daily and monthly data
daily_data <- result$daily
monthly_data <- result$monthly
} # }