Compound Drought and Heatwave event indicators for the Adige River catchment (1950-2023)

Resumo

The Compound Drought and Heatwave (CDHW) indicators dataset includes two netCDF files: one indicating the occurrence/absence of events (CDHW_occurrence_extended_Alps_daily_1950_2023.nc, hereafter File A) and the other representing the severity of those events (CDHW_severity_extended_Alps_daily_1950_2023.nc, hereafter File B). A CDHW event is determined by the co-occurrence of drought and heatwave conditions over at least 60% of the Adige catchment area. The indicators were derived using the E-OBS 0.1ºx0.1° daily gridded dataset (v29.0e), covering the period from 1950 to 2023, and the spatial domain [7.10, 44.10, 15.30, 49.10] (min longitude, min latitude, max longitude, max latitude in WGS84, EPSG:4326). A drought period is identified as a sequence of consecutive months with a negative Standardized Precipitation Index (SPI), starting with the first month where the SPI-6 (6-month timescale) falls below -1. Heatwaves are defined as periods of at least three consecutive days where the daily maximum temperature (TX) exceeds the 90th percentile for that specific calendar day, determined using a 31-day running mean centred on the day under evaluation and considering all values from 1950 to 2023. When two or more periods of consecutive exceedances are separated by one day with TX below the threshold, they are considered as a single heatwave occurrence and the day below the threshold is included in the event duration.  In File A, for each day in a CDHW event the grid cells where both drought and heatwave conditions are detected are flagged as "1". If the compound condition is not met, the cell is flagged as "0". In File B, the daily CDHW severity (dimensionless) is calculated for each day in the compound event as the product of the standardized daily TX over the days of the event and the absolute value of the SPI in the corresponding month. The calculation of the CDHW severity is similar to the one proposed by Mukherjee and Mishra (2021), but with the percentiles used in the standardization of TX varying with the day of the year.  Lastly, the list of CDHW events affecting the Adige catchment between 1950 and 2023 is provided in a csv file, including the start and end dates, the percentage of the area affected, and the total severity of the event (dimensionless). The total severity of the event is defined as the average of the CDHW severities of all grid cells in the Adige catchment experiencing the CDHW conditions. The total severity of the CDHW event at each grid cell is calculated as the sum of the daily severities during the event by considering only the days flagged as "1" in File A.