Spatial and temporal variation in rainy season droughts in the Indonesian Maritime Continent

Spatial and temporal droughts during rainy seasons are important climatic aspects to consider in water resources management. The dry spell index, a time-independent index that considers the characteristic of dry days, dry spell, seasonal length and evaporation rate in drought severity estimation, is supporting the analyses of the spatiotemporal variations of drought severity in the rainy season of the Indonesian Maritime Continent (IMC) between 1998 and 2018. The rainy season was determined using a modified anomalous accumulation. The results showed that an increase in dry spells produced a consistently increasing temporal drought during the rainy season across the IMC. Meanwhile, spatial variation suggested that although there is an increase in the rainy season total accumulated precipitation and duration, a large area within the monsoon regime also experiences increased drought severity, indicating more frequent extreme precipitation. Regional drought severity was classified as normal with a tendency of an increasing area under dry categories. Overall, the rainy season drought has increased in the IMC from 1998 to 2018, elevating the threats of reduced agricultural production.