Delineation of Dew Formation Zones in Iran Using Long-Term ModelSimulations and Cluster Analysis

Abstract. Dew is a non-conventional source of water that has been gaining interest over the last two decades, especially in arid and semi-arid regions. In this study, we performed a long-term (1979–2018) energy balance model simulation to estimate dew formation potential in Iran aiming to identify dew formation zones and to investigate the impacts of long-term variation in meteorological parameters on dew formation. The annual average of dew occurrence in Iran was ~ 102 days, with the lowest number of dewy days in summer (~ 7 days) and highest in winter (~ 45 days). The average daily dew yield was in the range of 0.03–0.14 L/m2 and the maximum was in the range of 0.29–0.52 L/m2. Six dew formation zones were identified based on cluster analysis of the timeseries of the simulated dew yield. The distribution of dew formation zones in Iran was closely aligned with topography and sources of moisture. Therefore, the coastal zones in the north and south of Iran (i.e., Caspian Sea and Oman Sea), showed the highest dew formation potential with 53 and 34 L/m2/year, whereas the dry interior regions (i.e., central Iran and the Lut Desert), with the average of 12–18 L/m2/year had the lowest potential for dew formation. Trend analysis results revealed a significance (p