ECMWF Reanalysis V5 (ERA 5) assimilates terrestrial- and space-based historical observations from January 1950 to present into a comprehensive, global gridded reanalysis dataset of past weather conditions. This is the ground truth dataset
Weekly on Thursday
Choose the system of measurement you want to use.
SI - International System of units is the metric system.
US - United States measurement system commonly used in the United States and most U.S. territories.
| Frequency |
|---|
| Hourly (only available through the API) |
| Daily |
| Weekly |
| Monthly |
| 3-Monthly |
Choose a date in the past based on selected timescale.
Limit your view to a specific area by selecting from a list of shapefiles that may be associated with your account. Geospatial files define one or more polygons that bound a region of interest. Select ‘Upload Map Area’ to upload a shapefile for your account. See Upload Shapefiles and Locations for additional detail. You will get a global view if None is selected.
<aside> 📌 Note: The HDD | CDD calculations are slightly different from the traditional definition. Salient’s HDD/CDD calculation is the mean hourly difference by which the temperature subceeds/exceeds a temperature threshold (65F/18C) over the course of a day. e.g. CDD = mean(floor(HourlyTemp-Threshold,0)) It is an hourly integral of temperature minus the base temperature. You can think of it as “mean degree-hours / day”.
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| Name | Variable | Unit | Description |
|---|---|---|---|
| Cloud Cover | cc | (0 - 1) | Percentage of the sky hidden by all visible clouds. |
| Cooling Degree Days | cdd | °C | °F |
| Diffuse Horizontal Irradiation | dhi | W/m² | Diffuse horizontal irradiation is the part of the solar irradiation which has been scattered by the atmosphere that reaches a surface. Only available for hourly historical. |
| Direct Normal Irradiation | dni | W/m² | Direct normal irradiation is the part of the solar irradiation that directly reaches a surface. Only available for hourly historical. |
| Evaporation | evap | mm/day | Evaporation is the accumulated amount of water that has evaporated from the Earth's surface, including a simplified representation of transpiration (from vegetation), into vapor in the air above. Negative values indicate evaporation and positive values indicate condensation. |
| Heating Degree Days | hdd | °C | °F |
| Geopotential Height (10 mbar) (250 mbar) (500 mbar) | hgt10 hgt250 hgt500 | m | ft |
| Sea Level Pressure | mslp | mbar | The sea level pressure is the atmospheric pressure at sea level at a given location. |
| Outgoing Longwave Radiation | olr | W/m² | Longwave radiation directed (upwards) away from the surface |
| Precipitation | precip | mm/day | Precipitation per day. To convert to an hourly rate (mm/hr), divide by 24. |
| Relative Humidity | rh | A dimensionless ratio, expressed in percent, of the amount of atmospheric moisture present relative to the amount that would be present if the air were saturated. Since the latter amount is dependent on temperature, relative humidity is a function of both moisture content and temperature. As such, relative humidity by itself does not directly indicate the actual amount of atmospheric moisture present. | |
| Sea Ice Cover | si | (0 - 1) | |
| Soil Moisture (upper 10 cm) | sm | m s**-1 | The total amount of water, including the water vapor, in an unsaturated soil level (upper 10 cm). |
| Snow Cover | snow | m | The areal extent of snow-covered ground. |
| Sea Surface Salinity | sss | psu | Sea surface salinity describes the amount of salt in the water at the ocean surface. |
| Sea Surface Temperature | sst | °C | °F |
| Soil Temperature (upper 10 cm) | st | °C | °F |
| Temperature (2m) | temp | °C | °F |
| Maximum Daily Temperature (2 m) | tmax | °C | °F |
| Minimum Daily Temperature (2 m) | tmin | °C | °F |
| Total Solar Insolation | tsi | W/m² | The amount of solar radiation that reaches the earth’s surface over a period of time. It is equivalent to ghi, Global Horizontal Irradiation. |
| Wind Speed (10 m) (100 m) | |||
| wspd wspd100 | |||
| m/s or mph | The rate at which air is moving horizontally past a given point at 10m or 100m height above ground level | ||
| Wind Direction (10 m) (100 m) | |||
| wdir | |||
| wdir100 | degrees | The true direction from which the wind is blowing at a given location (i.e., wind blowing from the north to the south is a north wind) at 10m or 100m height. It is normally measured in tens of degrees from 10 degrees clockwise through 360 degrees. North is 360 degrees. A wind direction of 0 degrees is only used when wind is calm. | |
| Wind Power (100m) | wpow | W/m² | Wind power which is proportional to a density calculation and 100m wind speed cubed. The formula is 0.5 * air_density * sqrt (u² + v²)³, where u and v are the wind components and air_density is calculated at ground level and T = 15 °C. |
| Maximum Wind Gust (10 m) | wgst | m/s | mph |
<aside> 📌 Hourly historical data is limited to “vals”.
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| Name | Variable | Description |
|---|---|---|
| Anomaly | anom | Deviation from selected reference period. |
| Detrended Anomaly | anom_d | Anomaly minus the trend. |
| Standardized Detrended Anomaly | anom_ds | |
| Anomaly Quantiles | anom_qnt | |
| Standardized Anomaly | anom_s | |
| Climatology | clim | Stationary 30 year climatology with smoothing and no trend. |
| Standard Deviation | stdv | |
| Trend | trend | |
| Value | vals |
If you click on a grid point in the web interface, a dialog displays the selected field for the chosen lat/lon coordinate.
The dialog provides a menu link to display the Historical Time Series.