Year-to-year fluctuations in fog-water collection in central Mediterranean Iberian Peninsula and the influential large-scale tropospheric circulation patterns

This study examines the mean annual cycles of monthly cumulated fog-water amounts (CFW) in the central Mediterranean Iberian Peninsula (MIP), highlighting the interplay between meteorological conditions, topography, and geographic location. Seasonal asymmetry in fog-water collection is evident, with summer exhibiting higher fog collection frequency but lower water volumes. In contrast, non-summer seasons feature lower frequency but higher intensity fog events.

Tropospheric circulation anomalies at mid- and low-tropospheric levels reveal that fog-water collection is influenced by moisture transport from the Mediterranean, particularly during high fog-collection months. Positive specific humidity anomalies near coastal areas, driven by southeasterly wind anomalies, are crucial for frequent fog formation, while broader, less concentrated anomalies characterize higher-intensity fog events. These findings align with prior research emphasizing the role of cyclonic conditions and maritime moisture advection in enhancing fog-water collection yields.

Additionally, seasonal variations in tropospheric circulation anomalies are linked to large-scale teleconnection patterns such as the North Atlantic Oscillation (NAO), Arctic Oscillation (AO), and Eastern Atlantic-Western Russia (EAWR) patterns. These modulate moisture advection, precipitation anomalies, and low-level winds that drive fog formation and collection. In summer, subtropical high-pressure weakening contributes to increased fog-water cumulates, while winter anomalies highlight the impact of quasi-stationary cyclonic circulations and autumn anomalies, positive NAO/AO phases.

These results underscore the climatic importance of fog-water collection for water resource management in drought-prone regions and provide a foundation for future climate monitoring and prediction under anthropogenic radiative forcing. The study's insights have practical implications for enhancing water availability through fog collection in Mediterranean ecosystems.