ERA5-Land datasets¶
ERA5-Land is a global reanalysis of land surface variables produced by ECMWF. It provides a consistent record from 1950 to the near-present at ~9 km resolution. The Open Climate Service ships six ERA5-Land data sources covering temperature and precipitation at daily and monthly resolution.
Setup¶
ERA5-Land data is fetched from two sources depending on the dataset. Both are free but require registration.
Earth Data Hub (monthly datasets and daily normals)¶
- Create a free account at earthdatahub.destine.eu.
- Go to Account settings → My API keys → Standard API keys and generate a key.
- Set it in
.env:
Copernicus Climate Data Store (daily datasets)¶
- Register at cds.climate.copernicus.eu and get your API key from your profile.
- Set it in
.env:
Set up before this release? OCS no longer reads ~/.netrc or ~/.ecmwfdatastoresrc; move both keys into .env. The daily datasets read from CDS, so they need the CDS key even where they once needed only Earth Data Hub.
Ingest your first ERA5-Land dataset¶
Once authenticated, ingest ERA5-Land daily temperature:
curl -s -X POST http://127.0.0.1:9000/ingestions \
-H "Content-Type: application/json" \
-d '{
"dataset_id": "era5land_temperature_daily",
"start": "2024-01-01",
"end": "2024-01-31",
"publish": true
}' | jq
Temperature datasets¶
Daily (from hourly)¶
| Property | Value |
|---|---|
| Dataset ID | era5land_temperature_daily |
| Variable | t2m |
| Units | °C |
| Period | Daily |
| Coverage | Global, 1950–present |
| Resolution | ~9 km |
| Source | CDS ERA5-Land analysis-ready data |
| Lag | ~5 days |
Daily mean temperature, averaged from the 24 hourly values of the UTC calendar day (00:00–23:59 UTC).
era5land_temperature_daily_min and era5land_temperature_daily_max are the same, with the daily minimum and maximum of the hourly values instead of the mean.
Monthly¶
| Property | Value |
|---|---|
| Dataset ID | era5land_temperature_monthly |
| Variable | t2m |
| Units | °C |
| Period | Monthly |
| Coverage | Global, 1950–present |
| Resolution | ~9 km |
| Source | Earth Data Hub ERA5-Land daily |
| Lag | Available after each month is complete in the source |
Monthly mean 2 m temperature, averaged from the Earth Data Hub daily means of the calendar month. Only complete months are ingested.
Precipitation datasets¶
Precipitation values represent total precipitation reaching the surface, including rain and snow as liquid-equivalent water. Units are mm/d, a daily rate: the daily value is the day's total in mm, and the monthly value is the mean of the daily totals. Multiply a monthly value by the number of days in the month for the monthly total.
Daily (from hourly)¶
| Property | Value |
|---|---|
| Dataset ID | era5land_precipitation_daily |
| Variable | tp |
| Units | mm/d |
| Period | Daily |
| Coverage | Global, 1950–present |
| Resolution | ~9 km |
| Source | CDS ERA5-Land analysis-ready data |
| Lag | ~6 days |
Total precipitation for the UTC calendar day, summed from the 24 hourly values of that day.
Each hourly precipitation value is the total for the hour ending at its timestamp, so the value stamped 00:00 belongs to the previous day. A day therefore sums the values stamped 01:00 through 00:00 the next day. The CDS publishes whole days of timestamps (00:00–23:00), so the hour that closes the latest day only arrives with the next day's update: precipitation always ends one day earlier than temperature, and that day is appended on the next sync.
Monthly¶
| Property | Value |
|---|---|
| Dataset ID | era5land_precipitation_monthly |
| Variable | tp |
| Units | mm/d |
| Period | Monthly |
| Coverage | Global, 1950–present |
| Resolution | ~9 km |
| Source | Earth Data Hub ERA5-Land daily |
| Lag | Available after each month is complete in the source |
Mean daily precipitation for the calendar month, averaged from the Earth Data Hub daily totals. Only complete months are ingested.
Humidity datasets¶
Daily dewpoint (from hourly)¶
| Property | Value |
|---|---|
| Dataset ID | era5land_dewpoint_daily |
| Variable | d2m |
| Units | °C |
| Period | Daily |
| Coverage | Global, 1950–present |
| Resolution | ~9 km |
| Source | CDS ERA5-Land analysis-ready data |
| Lag | ~5 days |
Daily mean 2 m dewpoint temperature, averaged from the 24 hourly values of the UTC calendar day. Dewpoint is the temperature at which water vapor will start condensing as dew.
Together with era5land_temperature_daily, it can be used as input to the relative_humidity_from_daily_dewpoint workflow, which publishes an estimated daily relative humidity where only daily inputs exist.
Daily relative humidity (from hourly)¶
| Property | Value |
|---|---|
| Dataset ID | era5land_relative_humidity_daily |
| Variable | rh |
| Units | % |
| Period | Daily |
| Coverage | Global, 1950–present |
| Resolution | ~9 km |
| Source | CDS ERA5-Land analysis-ready data |
| Lag | ~5 days |
Daily mean 2 m relative humidity for the UTC calendar day. It is computed for each hour from the hourly temperature and dewpoint, then averaged. Computing it from daily means instead underestimates it, most where days are hot and nights cool, because saturation vapour pressure rises exponentially with temperature. Ingesting it reads both hourly variables.
era5land_relative_humidity_daily_min and era5land_relative_humidity_daily_max are the same, with the daily minimum and maximum of the hourly values instead of the mean. The relative_humidity_from_daily_dewpoint workflow cannot produce these, as it estimates relative humidity from daily means only.
Choosing the right dataset¶
| Use case | Recommended dataset |
|---|---|
| Daily health modelling | era5land_temperature_daily / era5land_precipitation_daily |
| Monthly climate–health modelling | era5land_temperature_monthly / era5land_precipitation_monthly |
| CHAP integration (South Sudan, East Africa) | era5land_precipitation_monthly |