This text-file contains descriptive metadata for the wind resource data set NORA3-WP (NORwegian hindcast Archive's Wind Power data set). 
The user is encuraged to read the paper (doi:) for detailed information of the NORA3-WP generation process. 

Content:

NORA3-WP is based on the high-resolution hindcast archive from the Norwegian Meteorological institute, called NORA3 using modeleled wind data, together with air temperature, density and pressure, to estimate 43 relevant wind power and  wind resource variables. 
NORA3 is a dynamical downscaling of the ERA-5 reanalysis product from European Centre for Medium-Range Weather Forecasts (ECMWF) using the high-resolution numerical weather prediction (NWP) using the model HARMONIE-AROME (Cy 40h1.2). 
The downscaling is performed by solving the fully compressible Euler equations, on a non-staggered horizontal grid in a non-hydrostatic atmospheric mode. (DOI: 10.1175/2010MWR3425.1, DOI:  10.1175/MWR-D-16-0417.1)

Horizontal resolution:

The data is available on a 3 x 3 km horizontal grid covering the Norwegian continental shelf and the surrounding ocean areas (652 grid points in X-direction (longitude) and 1149 grid points in Y-direction (latitude)).

Temporal resolution:

NORA3-WP contains monthly values for all variables, providing climatological information at each grid cell. 
In addition, NORA3-WP also contain hourly wind speed and generated wind power data providing detailed high-frequency data available for more advanced analysis.

Wind resource variables:

The wind resource variables included and available in NORA3-WP (unit, statistic):
1. Hourly wind speed (m/s) (-)
2. Monthly wind speed (m/s) (mean, 25-, 50-, 75-, 95-percentile, std, max)
3. Monthly exponential power law coefficient, alpha (-) (mean)
4. Monthly Weibull scale and shape parameters (-) (-)
5. Monthly prevailing wind direction sector (deg) (mean)
6. Monthly vertical wind shear (m/s) (mean, max)
7. Monthly absolute ramp-rate (m/s) (mean, max)


Wind power related variables :

NORA3-WP wind power estimates are available for three selected turbines with different rated capacities and hub heights.
Turbine specifications for the three turbines used in the creation of NORA3-WP:
1. SWT-6.0-154 from Siemens. The floating three bladed electricity generator used in Hywind Scotland.
	a) Rated capacity (W): 6 000 000
	b) hub height (m): 101
	c) Rotor diameter (m): 154
	d) cut-in, rated, cut-out wind speed (m/s): 4, 13, 25
2. DTU-10.0-RWT is the widely used reference wind turbine from the Danish technological University (DTU).
	a) Rated capacity (W): 10 000 000
	b) hub height (m): 119
	c) Rotor diameter (m): 178.3
	d) cut-in, rated, cut-out wind speed (m/s): 4, 11.4, 25
2. IEA-15-240-RWT, the new reference turbine from the International Energy Agency (IEA).
	a) Rated capacity (W): 15 000 000
	b) hub height (m): 150
	c) Rotor diameter (m): 240
	d) cut-in, rated, cut-out wind speed (m/s): 3, 10.59, 25

The wind power related variables included and available in NORA3-WP:
1. Hourly generated power (W)
2. Monthly wind power density (W/m^2) (mean)
3: Monthly power capture (W/area^2) (mean)
4. Monthly generated power (W) (mean, 25-, 50-, 75-percentile)
5. Monthly generated power, density corrections (W) (mean)
6. Monthly generated power, SC1 and SC2 (W) (mean)
7. Monthly power capture coefficient (%) (mean, max)
8. Monthly generated power absolute ramp-rate (W) (mean, max)
9. Monthly cubed power generation (%) (-)
10. Monthly rated power generation (%) (-)
11. Monthly no generated power, low wind (%) (-)
12. Monthly no generated power, high wind (%) (-)
13. Monthly no generated power, total (%) (-)
14. Monthly no generated power, total, SC1 and SC2 (%) (-)
15. Monthly capacity factor (%) (-)
16. Monthly full load hours (h) (-)
17. Monthly full load hours, SC1 and SC2 (h) (-)

Nomenclature and abbreviations:
"SC1": "Storm control 1": Instead of an abrupt shut-down of the power production when the wind speed exceeds the cut-out limit a smooth shut-down and start-up procedure is practiced in SC1.
"SC2": "Storm control 2": When the wind speed exceeds the cut-out limit, the SC2 involves a termination of wind power generation until the wind speed is below a given wind speed threshold (u_co_new) lower than the cut-out limit (u_co).
Wind speed and wind power "ramp-rate": How much the wind speed or wind power change from one time step to the next (here: from one hour to the text).

Data format:

The available variables of NORA3-WP are stored as netCDF-files (.nc-files).
All variables are 5D matrices structured in the following way: variable(time, method, turbine/height, lat, lon)
"method" explaines which method used to calculate the variable in question. e.g. for the variables "WindSpeed_Percentiles" the dimension "method" = 4, and corresponds to the four percentiles calculated: 25-, 50-, 75-, and 95-percentile.
"turbine/height" corresponds to the height level/interval of the variable in question. the available height levels are: 101 m.a.s.l., 119 m.a.s.l., and 150 m.a.s.l. For some variables height-intervals are also available: 10-100 m.a.s.l., 50-100 m.a.s.l., 100-250 m.a.s.l.
To exclude all the land masks in the data set: Multiply the variable of interest with ind_excl_land_mask.nc

Data availability:
NORA3 data set can be downloaded her: https://thredds.met.no/thredds/projects/nora3.html
NORA3-WP can be downloaded her: