| Additional details |
The WBGT is derived from global daily maximum air temperature contained in ERA-Interim re-analysis fields for the period 1981-2010, which is considered of sufficient length to provide robust climate statistics. The 0.75° lat/lon fields are corrected for local-scale altitude effects by means of a high-resolution global digital elevation model, resulting in global daily maximum WBGT fields at a spatial resolution of approximately 10 km. These fields are temporally smoothed using a 3-day filter, so as to account for the cumulative effects of prolonged heat. These 30-year, 10-km resolution, 3-day smoothed daily maximum WBGT values are then employed to fit a Generalized Extreme Value (GEV) probability distribution function for each grid cell of the global domain. Considering return periods of 5, 20, and 100 years, 10-km hazard intensity maps have been calculated for each of these periods. To these hazard intensity maps, threshold values of 32°C, 28°C and 25°C, stemming from the scientific literature, subsequently are applied, resulting in a global heat risk map. |