Understanding inland fog and dew dynamics for assessing potential non-rainfall water use in the Atacama

In (semi-)arid regions, harvesting fog and dew can become a complementary solution to traditional water supply. In the Atacama region, a territory of key and water-dependent economic activities, both fog and dew are driven by the advection of marine moisture from the Pacific. Still, little is described regarding the dynamics and water potential of these events. In this study, we analyze the spatiotemporal variability of fog and dew in the Atacama Desert to assess the potential of non-rainfall atmospheric water harvesting. Our research strategy combines three methods to achieve a comprehensive understanding of these phenomena: a satellite-spatial analysis of fog and low cloud frequencies; a thermodynamic characterization of the fog cloud vertical structure; and an observational analysis of fog and dew water collection. Our findings reveal that fog is a regular phenomenon in the area, occurring from 3% to 20% of the year. We estimate that fog cloud reaches 50 km inland and up to ∼1100 m ASL, covering a vast territory where it can be harvested. Fog and dew represent 72% and 28% of the total collected atmospheric water (∼0.2 L m⁻² day⁻¹). Both fog and dew represent a complementary natural water source with multiple uses for local industries.