The mechanisms of dew formation and its influence on surface soil water content in the Central Ningxia arid belt
摘要
Dew formation and its influence on soil water content are an important basis for next-level quantification of water cycling and eco-hydrological processes. To reveal the dew formation process, over a consecutive 3-year period, we monitored meteorological parameters and soil water content in the top layer at 30-minute recording intervals in the Central Ningxia Province arid belt. The dew amount was measured using a leaf wetness sensor. Annual dew yield in this region reached 56.41 mm, 75% of which occurred from June to October. Maximum monthly and maximum daily dew were 13.40 mm and 0.80 mm, respectively, and mainly occurred in the early morning from 03:00 to 08:00 am. Meteorological parameters responsible for dew formation were: air temperature between 0—24.4 ℃, relative humidity between 50%—100%, wind speed between 0.16—1.74 m/s, and wind direction between 30—60 degrees and 270—330 degrees.There was a very significant and highly correlated linear and inverse relationship between relative humidity and the difference between air temperature and dewpoint. When the difference was < 3 ℃ and the corresponding humidity > 80%, dew formation was much more likely. When daily dew reached 0.6 mm, 0.7 mm and 0.8 mm, soil water storage in the top 5cm soil increased by 0.10 mm, 0.20 mm and 0.25 mm, respectively. Annual dewfall was 13.5% of the rainfall, and the annual frequency of dew occurrence was 126 days (35%), indicating that dew is a significant water source for local water and ecosystem cycling.