新疆阿勒泰克兰河中游地区冬季积雪分布及特性分析

Spatial distribution and features of the snow cover during accumulation period in the middle reaches of the Kelan River,Altay region,Xinjiang

新疆阿勒泰地区是中国季节性积雪水资源最为丰富的地区之一。2016年12月在克兰河中游地区开展了积雪观测,利用直尺和量雪筒测量雪深和雪密度,调查了积雪水资源的分布情况;利用针式温度计测量雪层温度,获取了雪层之间的温度梯度;利用雪特性分析仪和显微镜测量了积雪剖面的雪层密度、液态水含量、介电常数和雪粒径。通过分析研究区积雪水资源的空间分布和积雪特性的垂直分异发现:研究区雪深的分布非常不均匀,北部的雪深总体上大于南部,即使在同一地区,雪深也因风力等原因而分布不均匀;研究区总体上属于"干寒型"积雪,密度较小,且密实化迅速;各雪层属于干雪或者湿度极低的潮雪,绝大多数雪层的液态水含量在0.3%以下;积雪温度总体上从表层到底层逐渐升高,表层温度日变化较大;阴天积雪温度高于晴天,各雪层温度日变化小于晴天,且午后积雪会出现负温度梯度,冷中心出现在积雪次表层;雪粒径较小,雪粒长短轴比的最小值出现在中间层,且符合新雪的粒径特点。

Altay Prefecture of Xinjiang is one of the regions with abundant seasonal snow water resources in China. The snow properties in the middle reaches of the Kelan River were measured and the spatial and temporal features of them were analyzed. Snow depth and density were measured using snow scales, electronic scale and gauge. Using SnowFork and portable USB-loupe, the snow properties such as permittivity, wetness, density, grain size and temperature were measured in situ. Measurement of snow depth has indicated that the spatial distribution of snow depth in the study area is quite various and the snow depth in north is more than that in south. The water content less than 1% indicate that snow is dry or moist with less liquid water content. The snow densi- ty is approximate 0. 183 g ·cm^-3 on December 13 and 0. 199 g·cm^-3 on December 16, with a fast proceeding of densification. Temperature of snow cover increases generally from surface to bottom and the snow cover often works like a heat insulation layer. Snow temperature at any layers under cloudy is higher than that under sunny, but the diurnal variation of snow cover temperature under cloudy is less than that under sunny. There is lowest temperature in the sub-top of snow after 14：00 under cloudy. The grain size of snow is between fine and coarse, indicating that the snow is fresh.