EDO Heat and Cold Wave Index (version 1.0.0)

Heat- or coldwaves are classified by duration in days starting from more than one day. The present-day heat/cold wave is classified by accumulating all the past consecutive days with heat/cold wave until the present-day. However, for any past date the duration can also include the following days if the heat/cold wave persisted after the selected date. The Heat and Cold Wave Index (HCWI) that is implemented in the Copernicus European Drought Observatory (EDO) is used to detect and monitor periods of prolonged extreme-temperature anomalies (i.e. heat and cold waves) that can have specific impacts on human activities, health and ecosystem services. The HCWI indicator is computed for each location (grid-cell) of 1/4 decimal degree, based on the persistence for at least three consecutive days of events with both daily minimum and maximum temperatures (Tmin and Tmax) above the 90th percentile daily threshold (for heat waves) or below the 10th percentile daily threshold (for cold waves). For each grid cell, the daily threshold values for Tmin and Tmax are derived from a 30-year climatological baseline period (1981-2010), using the JRC’s MARS AGRI4CAST database of daily meteorological observations and computed interpolated minimum and maximum temperatures. Heat- and coldwaves are also detected during winter, respectively summer, in which a heatwave or coldwave can be perceived as pleasant by human beings but can have repercussions on ecosystem services. Examples are extended night frost in spring leading to damage of sprouts, or hot winter days leading to snow frost in high altitudes, subsequently leading to less water availability in streams during spring and summer. When temperature potentially dangerous for human beings were reached EDO will present an additional warning.