南京机场降水低能见度雨滴谱特征

对不同种降水对能见度的影响进行研究.选取连续性降水天气和雷暴天气两次过程的雨滴谱资料,计算后发现雷暴降水出现低能见度的雨滴谱较宽,而连续性降水雨滴谱的分布窄.粒子浓度和能见度呈反相关,在粒子浓度降低时能见度值有迅速的好转.在低能见度阶段小粒子的含量明显偏大些,1 mm以下的小粒子浓度对能见度的影响最大,其次是1～2 mm的小粒子,小粒子的高浓度对应着低能见度.出现降水并低能见度的时段时各特征量均为相对高值,能见度好转后突变转好并振荡,呈现相关.计算能见度在高粒子浓度和低能见度时与实测能见度接近.

Characteristics of Raindrop Size Distribution in Low Visibility Rainy Weather at Nanjing Airport

The changes of visibility in the different kinds of precipitation are studied. The raindrop size distribution data of two weather processes (continuous precipitation and thunderstorm) are analyzed. The results show that the thunderstorm precipitation with low visibility has a wide spectrum of drops, and the continuous precipitation has a narrow spectrum. The particle concentration and visibility are inversely related: the lower particle concentration leads to a rapid improvement in visibility. The concentration of small particles is significantly larger in low visibility, and the small concentration of particles less than 1 mm has the greatest impact on the visibility, followed by 1 to 2 mm particles, indicating that the high concentration of small particles corresponds to the low visibility. The characteristic quantities during precipitation and low visibility periods are relatively high, and after visibility improved, these quantities change suddenly and fluctuate. The calculated visibility is close to the observation at high particle concentration and low visibility.