Studies of the change on the composition and the optical properties of solid implities in deposited snow

雪表面的杂质会通过聚集降低反照率，从而显著加快融化速度，这是最重要的作用之一，特别是固体杂质，如矿物和生物颗粒。详细观察它们的光学特性，定量分析杂质的动态丰度、它们在能量收支中的光学作用和融雪速率之间的关系具有重要意义。在本研究中，首先对矿物粉尘的作用进行了实验研究。结果表明，随着熔炼的进行，杂质趋于聚集，反照率增大，导致熔炼速度减慢。也就是说，地表粉尘在融雪过程中具有负反馈作用。就冰川冰而言，融水的地表径流加速了这一效应。这一效应已被成功地纳入一个融雪模型。对于生物粉尘（雪藻）来说，繁殖的效果是一个水、光和营养丰富的功能，使其过程非常复杂。当我们只看生物量时，守恒定律在这种情况下就不成立了。因此，不可能将这一过程纳入融雪模型。然而，研究发现，生物颗粒可以作为确定年层的一个很好的指标，这在冰芯分析中有很大的用处。

Impurities on the snow surfaces would decrease the albedo and accordingly accelerate the rate of melting significantly through their aggregation, which is one of the most important roles, in particular of solid impurities such as mineral and biological particles. It is of great importance to observe their optical characteristics in detail, and to analyze quantitatively the relations between the dynamic abundance of impurities, their optical role in terms of energy budget and rate of snow melt.In this study, first of all, the role of mineral dust has been examined experimentally. It was found that the impurities tend to aggregate, as the melting proceeds, and the albedo increases resulting in retarding the rate of melting. In other words, the surface dust has an effect of negative feed back in snow melt. In case for glacier ice, the surface runoff of melt water accelerated the effect. This effect has been successfully incorporated in a snow melt model. For biological dust (snow algae), the effect of reproduction, which is a function of abundance of water, light and nutrient, make the process very complex. The conservation law does not hold in this case, when we look at the biomass only. It was not possible, therefore, to incorporate the process in the snow melt model. It was found, however, that the biological particles can be a good indicator for identifying annual layrs, which is of great use in ice core analysis.