Analysis of Raindrop Size Distribution Characteristics in Permafrost Regions of the Qinghai–Tibet Plateau Based on New Quality Control Scheme

• Published in: Water
• Main Authors: Lu Ma, Lin Zhao, Daqing Yang, Yao Xiao, Lele Zhang, Yongping Qiao
• Format: Article in Journal/Newspaper
• Language: English
• Published: MDPI AG 2019
• Subjects: raindrop size distribution; data quality control scheme; precipitation types; permafrost regions; Hydraulic engineering; TC1-978; Water supply for domestic and industrial purposes; TD201-500; permafrost
• Online Access: https://doi.org/10.3390/w11112265; https://doaj.org/article/c93b5b85436f49ff8be2b8c9515df64a

Raindrop size distribution (DSD) can reflect the fundamental microphysics of precipitation and provide an accurate estimation of its amount and characteristics; however, there are few observations and investigations of DSD in cold, mountainous regions. We used the second-generation particle size and velocity disdrometer Parsivel 2 to establish a quality control scheme for raindrop spectral data obtained for the Qinghai−Tibet Plateau in 2015. This scheme included the elimination of particles in the lowest two size classes, particles >10 mm in diameter and rain rates <0.01 mm <math display="inline"> <semantics> <mo>·</mo> </semantics> </math> h −1 . We analyzed the DSD characteristics for different types of precipitation and rain rates in both permafrost regions and regions with seasonally frozen ground. The precipitation in the permafrost regions during the summer were mainly solid with a large particle size and slow fall velocity, whereas the precipitation in the regions with seasonally frozen ground were mainly liquid. The DSD of snow had a broader drop spectrum, the largest particle size, the slowest fall velocity, and the largest number of particles, followed by hail. Rain and sleet shared similar DSD characteristics, with a smaller particle size, slower velocity, and smaller number of particles. The particle concentration for different classes of rain rate decreased with an increase in particle size and decreased gradually with an increase in rain rate. Precipitation with a rain rate >2 mm <math display="inline"> <semantics> <mo>·</mo> </semantics> </math> h −1 was the main contributor to the annual precipitation. The dewpoint thresholds for snow and rain in permafrost regions were 0 and 1.5 °C, respectively. The dewpoint range 0−1.5 °C was characterized by mixed precipitation with a large proportion of hail. This study provides valuable DSD information on the Qinghai−Tibet Plateau and can be used as an important reference for ...