A revision of the Combined Drought Indicator (CDI) used in the European Drought Observatory (EDO)

Abstract. Building on almost 10 years of expertise and operational application the Combined Drought Indicator (CDI), which is implemented within European Commission's Observatory (EDO) for purposes early warning monitoring agricultural droughts in Europe, this paper proposes a revised version index. The CDI conceptualizes drought as cascade process, where precipitation shortage (WATCH stage) develops into soil water deficit (WARNING stage), turn leads to stress vegetation (ALERT stage). main goal proposed here improve indicator's performance those events that are currently not reliably represented, without altering either modelling conceptual framework or required input datasets. This achieved by means two modifications: (a) use previously occurring value temporal consistency time series (b) introduction temporary classes – namely TEMPORARY RECOVERY moisture greenness, respectively avoid brief discontinuities stage. efficacy modifications tested comparing performances versions indicator actual Europe during last 20 years. reproduces evolution major droughts, outperforming current indicator, especially long-lasting events, reducing overall inconsistencies stage sequencing about 70 %. Since does need supplementary datasets, it suitable implementation EDO system.