Data Description¶
This page describes the Energy Indicators variables, units, conventions, spatial and temporal characteristics, and file formats.
Available indicators¶
Note
For detailed references and more information about the indicators, see the energy_indicators README.
Wind indicators¶
High wind events
High wind events quantify the percentage occurrence of wind speeds exceeding the turbine cut-out speed, indicating periods when turbines shut down to avoid mechanical damage. The indicator is produced operationally using a 25 m s⁻¹ cut-out threshold by default.
Low wind events
Low wind events represent the percentage occurrence of wind speeds below the turbine cut-in speed, when turbines cannot generate electricity due to insufficient wind energy. The indicator is produced operationally using a 3 m s⁻¹ cut-in threshold by default.
99th percentile 100 m wind speed
Extreme wind indicator showing the 99th percentile of 100 m wind speed over a month, providing information on extreme wind conditions.
Maximum 100 m wind speed
Maximum wind speed at 100 m height. It is provided in monthly outputs.
100 m wind speed histograms
Wind speed histograms at 100 m height. These represent raw wind speed distributions used to characterise wind resource availability, which is relevant for wind energy production. They are based on the hourly climate model outputs.
Production indicators¶
Capacity factor histograms
Capacity factor represents the ratio of actual energy produced by a wind turbine to the theoretical maximum possible energy output if the turbine operated at rated power. Capacity factor histograms are operationally produced for four turbine types.
Note
Histograms are provided as a composition of 2 files: bin edges and bin counts. Bin edges stands for the limits of every counting box, while the bin counts stands for the frequency of occurrence of the event comprised between the limits of a counting box. A histogram with n bins needs n + 1 bin limits (edges) because the limits define the boundaries of the bins. Therefore the dimensions of “bin_edges” are always the dimension of “bin_counts” + 1.
Turbine |
IEC class |
Hub height [m] |
Rated power [MW] |
Cut-in speed [m s⁻¹] |
Rated speed [m s⁻¹] |
Cut-out speed [m s⁻¹] |
|---|---|---|---|---|---|---|
Enercon E70 |
I |
85 |
2.3 |
2.0 |
15.0 |
25.0 |
Gamesa G87 |
II |
83.5 |
2.0 |
3.0 |
14.0 |
25.0 |
Vestas V110 |
III |
100 |
2.0 |
4.0 |
12.0 |
20.0 |
Vestas V164 |
S |
105 |
9.5 |
3.5 |
14.0 |
25.0 |
Solar indicators¶
Photovoltaic potential
Photovoltaic (PV) potential represents the available solar energy for power generation based on surface downwelling shortwave solar irradiance, 2 m air temperature, and near-surface wind conditions (Ghosh et al., 2024) [Ghosh et al., 2024].
Demand indicators¶
Heating degree days
Heating degree days quantify how much, and for how long, air temperature falls below a base temperature. They provide a proxy for heating energy demand required to maintain indoor thermal comfort. The indicator is produced operationally using a 15.5 °C base temperature.
Cooling degree days
Cooling degree days measure how much, and for how long, air temperature exceeds a base temperature. They provide a proxy for cooling energy demand for air conditioning and indoor thermal comfort. The indicator is produced operationally using a 22 °C base temperature.
Variables and parameters¶
Variable |
Short name |
Unit |
Dimensions |
Type |
Description |
Note |
|---|---|---|---|---|---|---|
Monthly Capacity Factor Histogram (Turbine Type I - Counts) |
cf_I_counts |
counts |
lat, lon, time |
data (forecast) |
Frequency of hourly capacity factor values (0-1) grouped into histogram bins for turbine type I |
Must be used together with bin edges file |
Monthly Capacity Factor Histogram (Turbine Type I - Bin Edges) |
cf_I_bin_edges |
MW/MW |
lat, lon, time |
data (forecast) |
Defines the boundaries of histogram bins for turbine type I capacity factors |
Must be used together with bin counts file |
Monthly Capacity Factor Histogram (Turbine Type II - Counts) |
cf_II_counts |
counts |
lat, lon, time |
data (forecast) |
Frequency of hourly capacity factor values (0-1) grouped into histogram bins for turbine type II |
Must be used together with bin edges file |
Monthly Capacity Factor Histogram (Turbine Type II - Bin Edges) |
cf_II_bin_edges |
MW/MW |
lat, lon, time |
data (forecast) |
Defines the boundaries of histogram bins for turbine type II capacity factors |
Must be used together with bin counts file |
Monthly Capacity Factor Histogram (Turbine Type III - Counts) |
cf_III_counts |
counts |
lat, lon, time |
data (forecast) |
Frequency distribution of hourly capacity factors for turbine type III |
Must be used together with bin edges file |
Monthly Capacity Factor Histogram (Turbine Type III - Bin Edges) |
cf_III_bin_edges |
MW/MW |
lat, lon, time |
data (forecast) |
Histogram bin boundaries for turbine type III capacity factors |
Must be used together with bin counts file |
Monthly Capacity Factor Histogram (Turbine Type S - Counts) |
cf_S_counts |
counts |
lat, lon, time |
data (forecast) |
Frequency of hourly capacity factors for turbine type S |
Must be used together with bin edges file |
Monthly Capacity Factor Histogram (Turbine Type S - Bin Edges) |
cf_S_bin_edges |
MW/MW |
lat, lon, time |
data (forecast) |
Bin boundaries for turbine type S capacity factor histogram |
Must be used together with bin counts file |
Cooling Degree-Days |
cdd |
K |
lat, lon, time |
data (forecast) |
Accumulated temperature above a reference threshold, indicating cooling demand |
|
Heating Degree-Days |
hdd |
K |
lat, lon, time |
data (forecast) |
Accumulated temperature below a reference threshold, indicating heating demand |
|
Low Wind Events |
lwe |
lat, lon, time |
data (forecast) |
Periods where wind speed falls below a defined threshold |
||
High Wind Events |
hwe |
lat, lon, time |
data (forecast) |
Periods where wind speeds exceed a defined threshold |
||
Monthly Wind Speed Histogram (Counts) |
counts |
lat, lon, time |
data (forecast) |
Frequency distribution of wind speeds across bins |
Must be used together with bin edges file |
|
Monthly Wind Speed Histogram (Bin Edges) |
bin_edges |
m s⁻¹ |
lat, lon, time |
data (forecast) |
Defines bin boundaries for wind speed histogram |
Must be used together with bin counts file |
Daily Photovoltaic Potential |
pvp |
kWh m⁻² |
lat, lon, time |
data (forecast) |
Estimated daily solar energy output per square metre |
|
Daily Wind Speed Maxima |
ws |
m s⁻¹ |
lat, lon, time |
data (forecast) |
Maximum wind speed recorded per day |
|
99th Wind Speed Percentile |
ws_99 |
m s⁻¹ |
lat, lon, time |
data (forecast) |
Wind speed value below which 99% of observations fall |
Spatial and temporal coverage¶
The indicators are provided at global scale on a regular latitude/longitude grid at the native resolution of the climate model (~5km). The temporal extent of the data is the same as the temporal extent of the climate simulations. Reported data errata are documented in the Data Quality and Evaluation page.
For selected offshore wind indicators (percentiles and histograms), a 200 km offshore mask is applied to exclude locations currently considered unviable for renewable energy installations.
Temporal aggregation varies by indicator:
Daily indicators are: photovoltaic potential, heating degree-days, cooling degree-days, and daily wind speed maxima (the latter aggregated in monthly files).
Monthly indicators are: wind speed histograms, capacity factor histograms and 99th percentile of 100 m wind speed.
File formats¶
All the indicators are provided in NetCDF format, following CF conventions. The data files are structured with dimensions for latitude, longitude, and time, and include metadata describing the variables, units, and other relevant information.