有无遮蔽条件下季节性积雪分层物理特性对比分析

【目的】融雪径流是干旱内陆河流重要的补给组成。季节性积雪对环境变化极为敏感,研究影响季节性积雪积累与融雪过程的关键因素并进行调控,对变化环境下流域安全与水资源可持续利用具有重要意义。【方法】通过对新疆天山北坡乌鲁木齐河流域试验区2017年11月—2018年2月有无遮蔽条件下(林冠下、开阔地)季节性积雪层分层物理特性进行观测,分析季节性积雪层分层物理特性差异特征。【结果】①观测期开阔地气温略高于林冠下气温,而林冠下相对湿度高于开阔地;②林冠下积雪平均深度小于开阔地,分层积雪中深霜层与粗粒雪层深度比例较大;③林冠下与开阔地分层积雪密度垂直廓线变化特征基本一致,雪层密度从新雪层向下逐渐增大,至粗雪层(开阔地)与中粒雪层(林冠下)达峰值;④林冠下与开阔地分层雪温和分层液态含水率均自新雪层至深霜层呈上升趋势;⑤林冠下与开阔地雪水当量变化趋势基本一致,且开阔地雪水当量值明显大于林冠下。【结论】雪表温度是显著影响林冠下及开阔地积雪液态含水率的因素。

Comparative Analysis of Stratified Physical Characteristics of Seasonal Snow Cover With or Without Shading

【Objective】Snow melting runoff is an important recharge component of arid inland rivers. Seasonal snow cover is very sensitive to environmental change. Therefore, it is of great significance to study and control the key factors affecting seasonal snow accumulation and snow melting process for basin safety and sustainable utilization of water resources under changing environment【.Method】By observing the physical characteristics of seasonal snow layers under the conditions of sheltered or not(under canopy and open land) in the Urumqi River Basin experimental area on the northern slope of Tianshan Mountains in Xinjiang from November 2017 to February 2018, the differences of physical characteristics of seasonal snow layers were analyzed【.Result】(1) the temperature of open land was slightly higher than that of under canopy, and the relative humidity under canopy was higher than that of open land.(2)The average depth of snow under canopy was less than that of open land, and the proportion of deep frost layer to coarse snow layer was larger in stratified snow cover.(3) The vertical profile of snow density under canopy was basically the same as that under open land. The snow density increased gradually from the new snow layer down to the peak of coarse snow layer(open land) and medium-sized snow layer(under canopy).(4) Snow temperature and liquid water content of layers under canopy and open land increased from new snow layer to deep frost layer.(5) The variation trend of snow water equivalence under canopy and open ground was basically the same during observation period. The value of snow water equivalence under open ground was obviously larger than that under canopy【.Conclusion】Snow surface temperature is a significant factor affecting the liquid water content of snow under canopy and open land.