Fog types frequency and their collectable water potential in the Atacama Desert

Abstract

Fog is a widespread phenomenon in the coastal Atacama Desert. Within this region, three types of fog have been described: advective, orographic, and radiative. However, there remains a lack of quantification regarding their frequencies, the physical mechanisms responsible for their formation, and their contribution to fog water collection. Our research quantifies for the first time in the Atacama Desert the frequency of each fog type, the physical conditions conducive to their formation, and their potential for water collection. Using high temporal resolution (10 min) GOES satellite imagery, we define geographical criteria related to the regular area of presence of different types of fogs that allowed us to analyze their frequencies at multiple time scales. Our results reveal that advective fog accounts for ~76 % of total fog events, with orographic fog ~22 % and radiative fog ~2 %. The main physical mechanisms driving advective and orographic fog formation are the sea surface temperature and the thermal inversion layer, whereas for radiative fog formation, it is mainly controlled by the marine boundary layer height. On a monthly scale, advective fog contributes to 60 % of water collection, while orographic fog accounts for 40 %. At the diurnal scale, orographic fog has a higher collection rate per hour. This inversion is influenced by local-scale variables such as wind speed, which plays a crucial role in water collection on a diurnal scale, enhancing orographic fog formation and its relative contribution during afternoon hours. Our research enhances the understanding of fog as a spatial-meteorological phenomenon and a potential water resource, offering a straightforward methodology for classifying fog types in coastal arid regions worldwide.