风吹雪动力过程观测与参数化方法研究

Blowing snow is the transmission process of mass and energy, which induce tremendous spatial heterogeneity of snow distribution and melt differences, Consequently directly changes the energy fluxes between land and atmosphere, affects snowmelt runoff patternsis, Spatially and temporally can strongly influence ecosystem structure and function. But the related mesaurements and research work of blowing snow are rare. How to get the accruate spatial distribution of blowing snow, aslo its evolution mechanism and parameterization are all very important and frontier issues in snow hydrology. This study is about to carry out in Qilian Alpine Ecology & Hydrology Research Station, we select the cold and high altitude watershed in Qilian Mountainous as a typical region to monitor and simulate snow accumulation and melt processes. By the use of scientific instruments such as SNOWFORK, SR50 SONIC RAANGING SENSOR, FlowCapt, Snow pillow, Weighted Rain and Snow Gauges et al., we obtain data which include snow depth, densities and water content on point and line scales, also we get spatio-temporal characteristics of the snow cover evolution on watershed scale by the using of digital cameras. Depend on the multi scale observation system, a blowing snow model is established which considers the complex terrain and varigous vegetation. By the help of simulation technique, we are about to study the mechanism of blowing evolution observation field and watershed scales.Through multi-scale observation, modeling and verification, we are about to study the effect of terrain and vegetation on blowing snow.

风吹雪作为一种特殊的质能输送过程，造成积雪时空分布的不均一性，进而形成消融差异，不仅直接改变全球陆面与大气能量的交换，导致流域融雪径流的年际与年内变化，甚至影响着生态系统结构和功能。目前风吹雪相关的观测和研究较少，如何精细刻画风吹雪动力过程及其参数化方案是当前雪水文学研究的前沿和难点。本研究拟在祁连山生态水文试验研究站试验小流域，利用SNORFORK、雪枕、雪深探头、雨雪量计、风吹雪粒子测量仪等多套仪器设备，从多点、观测场、测线等尺度获取雪深、密度、雪层含水量等的变化信息，利用摄影测量方法同步获取高精度、高时空分辨率的积雪时空演化过程信息，并充分考虑复杂地形和植被的影响，构建高寒山区风吹雪动力过程模型并探讨其参数化方案，模拟观测场和流域尺度的积雪时空演化过程，认识微地形和植被等对风吹雪过程的影响程度。

风吹雪作为一种特殊的质能输送过程，造成积雪时刻分布的不均一性，进而形成消融的差异。采用2015以来在祁连山葫芦沟流域观测的雪深、积雪分布和照片，以及八一冰川顶部雪深和照片数据，分析了祁连山风吹雪在山区不同海拔梯度和不同坡向发生的特点和规律。结果表明：风吹雪发生频率和强度随海拔升高呈增加趋势。年内分配上则主要集中在每年的9月-11月，以及次年的3月-4月，这与该区域降雪发生的时段较为一致。风吹雪发生的时段在低海拔主要集中在降雪过程中，随海拔的升高，风吹雪在降雪后发生的概率相对提高。阴坡、阳坡积雪对比研究表明：风吹雪在阴坡的强度和概率应该远高于阳坡，并且阳坡风吹雪发生的时段应该主要集中在降雪时段。不同海拔梯度降雪量巨大的差异表明降雪过程中风的扰动加剧了降雪在高海拔地区丰沛而低海拔稀少的分布特征。风成为降雪过程和降雪后积雪在分布的的主要控制因素。也就是说风吹雪不仅导致了地表积雪的再分布，其在降雪过程中对降雪分布也产生巨大的影响。采用盛行风与地形的计算，对胡芦沟流域及其周边地区的积雪空间分布进行了参数化，充分考虑了风对积雪空间分布的影响。