Variation of Dry Days Since Last Rain (DDSLR) as a measure of dryness along a Mediterranean - Arid transect

Dry periods between rainstorms control the soil moisture conditions, and are the antecedent conditions for various geomorphological, hydrological and ecological processes. An annual distribution of dry condition, based on the Dry Days Since Last Rain (DDSLR) approach is presented, showing the duration and timing of dry periods for various daily rainfall thresholds and probabilities. Daily rainfall data from five stations along a climatic transect in Israel, extending from the Judean Mountains, which have a Mediterranean climate, to the Dead Sea arid region were studied. The results show that DDSLR values increased with increasing aridity. At a 0.1 mm rainfall threshold, the DDSLR values were similar along this transect. However, at higher daily thresholds, differences among different locations along the transect, become more noticeable.