ERA5

ERA5 is ECMWF’s fifth-generation global climate reanalysis, combining historical observations with numerical weather prediction models to produce a comprehensive, consistent record of past weather and climate from 1940 to present. Data is accessed via the Copernicus Climate Data Store (CDS) API.

MetaData(ERA5())

MetaData("CDSAPI_KEY", "1 concurrent job", :weather, Dict(:u_wind_10m => "10m u-component of wind (m/s)", :total_cloud_cover => "Total cloud cover (0–1)", :volumetric_soil_water_1 => "Volumetric soil water layer 1 (m³/m³)", :dewpoint_temperature_2m => "2m dewpoint temperature (K)", :surface_pressure => "Surface pressure (Pa)", :skin_temperature => "Skin temperature (K)", :snowfall => "Snowfall (m of water equivalent)", :evaporation => "Total evaporation (m of water equivalent)", :temperature_2m => "2m temperature (K)", :v_wind_10m => "10m v-component of wind (m/s)"…), :raster, "0.25° (~25 km)", "Global", :timeseries, Hour(1), "1940–present", "CC BY 4.0", "https://cds.climate.copernicus.eu/", Dict("Rasters" => "a3a2b9e3-a471-40c9-b274-f788e487c689"))

Setup

Create a free account at https://cds.climate.copernicus.eu/
Accept the ERA5 dataset license on the CDS website
Get your Personal Access Token from https://cds.climate.copernicus.eu/profile
Set the CDSAPI_KEY environment variable:

ENV["CDSAPI_KEY"] = "your-personal-access-token"

Basic Usage

using GeoDataAccess
using GeoDataAccess: ERA5, DataAccessPlan, fetch
using GeoInterface.Extents: Extent
using Dates

# Temperature and precipitation over Europe for 3 days
ext = Extent(X=(-10.0, 30.0), Y=(35.0, 60.0))
plan = DataAccessPlan(ERA5(), ext, Date(2024, 1, 1), Date(2024, 1, 3);
    variables = [:temperature_2m, :total_precipitation])
files = fetch(plan)

Specific Times

By default, data is retrieved at 6-hourly intervals (00:00, 06:00, 12:00, 18:00). Request all 24 hours or specific times:

# All hours
plan = DataAccessPlan(ERA5(), ext, Date(2024, 7, 1), Date(2024, 7, 1);
    variables = [:temperature_2m],
    times = [lpad(h, 2, '0') * ":00" for h in 0:23])

# Only noon
plan = DataAccessPlan(ERA5(), ext, Date(2024, 7, 1), Date(2024, 7, 31);
    variables = [:temperature_2m],
    times = ["12:00"])

Options

Option	Type	Default	Description
`variables`	`Vector{Symbol}`	`[:temperature_2m]`	Variables to retrieve
`dataset`	`String`	`"reanalysis-era5-single-levels"`	CDS dataset identifier
`product_type`	`String`	`"reanalysis"`	`"reanalysis"` or `"ensemble_members"`
`times`	`Vector{String}`	`["00:00","06:00","12:00","18:00"]`	Hours to retrieve (UTC)
`data_format`	`String`	`"netcdf"`	`"netcdf"` or `"grib"`

Common Variables

Symbol	CDS Name	Description
`:temperature_2m`	`2m_temperature`	Air temperature at 2m (K)
`:dewpoint_temperature_2m`	`2m_dewpoint_temperature`	Dewpoint temperature at 2m (K)
`:u_wind_10m`	`10m_u_component_of_wind`	U-wind at 10m (m/s)
`:v_wind_10m`	`10m_v_component_of_wind`	V-wind at 10m (m/s)
`:total_precipitation`	`total_precipitation`	Total precipitation (m)
`:surface_pressure`	`surface_pressure`	Surface pressure (Pa)
`:mean_sea_level_pressure`	`mean_sea_level_pressure`	Mean sea level pressure (Pa)
`:skin_temperature`	`skin_temperature`	Skin temperature (K)
`:sea_surface_temperature`	`sea_surface_temperature`	Sea surface temperature (K)
`:total_cloud_cover`	`total_cloud_cover`	Total cloud cover (0–1)
`:low_cloud_cover`	`low_cloud_cover`	Low cloud cover (0–1)
`:high_cloud_cover`	`high_cloud_cover`	High cloud cover (0–1)
`:surface_solar_radiation`	`surface_solar_radiation_downwards`	Surface solar radiation (J/m²)
`:surface_thermal_radiation`	`surface_thermal_radiation_downwards`	Surface thermal radiation (J/m²)
`:snowfall`	`snowfall`	Snowfall (m of water eq.)
`:snow_depth`	`snow_depth`	Snow depth (m of water eq.)
`:soil_temperature_level_1`	`soil_temperature_level_1`	Soil temperature level 1 (K)
`:volumetric_soil_water_1`	`volumetric_soil_water_layer_1`	Volumetric soil water layer 1 (m³/m³)
`:boundary_layer_height`	`boundary_layer_height`	Boundary layer height (m)
`:evaporation`	`total_evaporation`	Total evaporation (m of water eq.)

Loading Data

Loading ERA5 NetCDF/GRIB files requires the Rasters package:

using Rasters

raster = load(plan)  # returns Raster or RasterStack