get_era5: Fetch ERA5 Data from Open-Meteo for Multiple Locations

In r4pde: Tools for Quantitative Plant Disease Epidemiology

Fetch ERA5 Data from Open-Meteo for Multiple Locations

Description

This function downloads ERA5 historical weather data from the Open-Meteo API for specified locations and dates. It mimics the functionality of get_nasapower by fetching weather variables and returning a daily-aggregated data frame. It uses the Open-Meteo Archive API and aggregates hourly data to daily values to ensure all variables (including relative humidity and dew point) are available.

Usage

get_era5(
  data,
  days_around,
  date_col,
  study_col = "study",
  pars = c("temperature_2m", "relative_humidity_2m", "precipitation", "dewpoint_2m"),
  models = NULL,
  direction = "both"
)

Arguments

data	A data frame containing the input data, including columns for latitude, longitude, and the date column specified by date_col.
days_around	An integer specifying the number of days before and after the date in the date column to download data.
date_col	A character string specifying the name of the date column in the data frame.
study_col	A character string specifying the name of the column containing the study identifier in the input data frame (default: "study").
pars	A character vector specifying the weather variables to fetch from Open-Meteo. These are mapped to nasapower equivalents: "temperature_2m" (T2M), "relative_humidity_2m" (RH2M), "precipitation" (PRECTOTCORR), etc.
models	A character string specifying the reanalysis model(s) to use. If NULL (default), Open-Meteo uses its "best_match" logic (ERA5, ERA5-Land, etc.).
direction	Character string specifying the direction of the date range relative to the reference date. Options are "both" (default), "back", or "forth". "back" retrieves data from date - days_around to date. "forth" retrieves data from date to date + days_around. "both" retrieves data from date - days_around to date + days_around.

Details

Since the Open-Meteo Archive API daily endpoint does not provide all variables (like mean relative humidity) directly, this function fetches hourly data and performs the daily aggregation manually:

• T2M: Mean of hourly temperature_2m

• T2M_MAX: Max of hourly temperature_2m

• T2M_MIN: Min of hourly temperature_2m

• RH2M: Mean of hourly relative_humidity_2m

• PRECTOTCORR: Sum of hourly precipitation

• T2MDEW: Mean of hourly dewpoint_2m

Value

A data frame (tibble) with daily weather data. Columns are named to match nasapower conventions: date, T2M, T2M_MAX, T2M_MIN, RH2M, PRECTOTCORR, T2MDEW, longitude, latitude, and study.

See Also

Other Disease modeling: get_brdwgd(), get_nasapower(), windowpane()

r4pde documentation built on Sept. 8, 2026, 1:10 a.m.