Fig. 3: Calibration coefficient K(daily−1hour) derived from observational data and climate reanalysis. | Nature Communications

Fig. 3: Calibration coefficient K(daily−1hour) derived from observational data and climate reanalysis.

From: Detecting and calibrating large biases in global onshore wind power assessment across temporal scales

Fig. 3

a Global distribution of K(daily−1hour) derived from observational data spanning 1973–2021. b Global distribution of K(daily−1hour) calculated from the fifth-generation European Centre for Medium-Range Weather Forecasts (ECMWF) atmospheric reanalysis (ERA5) for the same period. c Scatter plots of wind power density (WPD, daily) versus K(daily−1hour) based on observations. The color bar represents point density, computed in linear WPD space but displayed on a logarithmic x-axis for clarity. *** denotes statistical significance at the 99.9% confidence level (t-test). d Boxplots of K(daily−1hour) categorized by WPD levels (WPL, I–VI), as defined by the National Renewable Energy Laboratory7. Levels I–VI correspond to WPD ranges of 0–50, 50–100, 100–200, 200–300, 300–400, and >400 W m-2, respectively, based on observational data. Median K values are indicated by red lines within each box. Outliers (K(daily-1hour)>5.0, accounting for less than 1.9% of total sites) were excluded from the analysis due to anomalously low WPD values, likely resulting from data anomalies. Data for the boxplots are provided in Supplementary Table 3. Source data are provided as a Source Data file.

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