Formation and variations of dew and hoarfrost in the Hulu Catchment on Northeast Qinghai-Tibet Plateau, China

Abstract

Study region: The Hulu Catchment on Northeast Qinghai-Tibet Plateau, China Study focus: Dew and hoarfrost (DH) are prominent components of the Non-Precipitation Water Inputs in arid and semi-arid regions, but research into them is mostly neglected in alpine regions. To understand the formation and variations of DH, as well as whether DH has a significant impact on the water balance and ecosystem, a field measurement experiment of dew was conducted in the Hulu Catchment. Meanwhile, the amount, duration, and frequency of DH at different elevations in the Hulu Catchment from 2016 to 2020 were estimated using the Penman equation. New hydrological insights for the region: DH was common weather phenomenon in the Hulu Catchment, with small interannual and large monthly variations in amount, duration, and frequency. DH showed significant seasonal pattern and elevation dependence, which depending on the seasonal pattern and elevation dependence of meteorological factors. The mean annual amount of DH ranged from 3 mm to 33 mm, contributing 0.3–7.3% of precipitation, indicating that DH was not a critical component of water balance. Nevertheless, DH was ecologically important in replenishing surface soil water deficits and mitigating diurnal fluctuations in surface temperature, protecting vegetation and microorganisms from water and temperature stress in alpine regions. This study has important implications for understanding the energy transfer, water cycle and ecosystem operation in alpine regions.

Keywords

• Dew
• Hoarfrost
• Alpine region
• Penman equation
• Seasonal pattern
• Elevation dependence