Use of a multilayer snow model to assess grazing conditions for reindeer
Use of a multilayer snow model to assess grazing conditions for reindeer
复制标题
使用多层雪模型评估驯鹿的放牧条件
作者：
Dagrun Vikhamar;Inger Hanssen;T. Schuler;Svein D. Mathiesen;M. Lehning
摘要冬季高密度的积雪使驯鹿放牧条件恶化。我们比较了两种不同的方法来识别过去的冬天，艰难的放牧条件下，在Kautokeino，挪威北方驯鹿。基于月降水量和温度值（1900-2011年）的长期气候分析表明，报告的冬季很难系统地确定。导致硬层或地冰层的过程每天发生，而不是每月，时间尺度，具体条件是否有问题取决于整个冬季的发展，而不仅仅是单一的值。为了更好地分析有利于高密度雪层形成的天气条件和随时间的发展，我们应用了1956-2010年期间的多层模型SNOWPACK。我们模拟积雪的演变，迫使模式与6小时间隔的气象资料。通过总结每个冬季模拟的高密度雪层（>350 kg m-3）的垂直范围，对模型输出进行了分析。这些结果与1956-2010年期间报告的冬季放牧条件困难的历史记录进行了比较。特别是，在1967/68年灾难性的冬季，由于地面结冰加上积雪时间长，驯鹿损失惨重。我们的模型结果很好地再现了这种不利的巧合，以及十个报告的困难冬季中的八个。
Abstract High-density snow layers deteriorate grazing conditions for reindeer during winter. We compare two different methods for identifying past winters with difficult grazing conditions for reindeer in Kautokeino, northern Norway. A long-term climate analysis based on monthly values of precipitation and temperature (1900–2011) demonstrated that the reported winters were difficult to identify systematically. The processes leading to hard layers or ground-ice layers occur on daily, not monthly, timescales, and whether or not specific conditions are problematic depends on the development throughout the winter, not just on single values. To better analyse the weather conditions and development over time that favour the formation of high-density snow layers, we apply the multilayer model SNOWPACK over the period 1956–2010. We simulate the evolution of the snowpack by forcing the model with 6 hour interval meteorological data. The model output was analysed by summing up the vertical extent of the simulated high-density snow layers (>350 kg m–3) for each winter. These results were compared with historical records of difficult winter grazing conditions reported in the period 1956–2010. In particular, the heavy losses of reindeer during the catastrophic 1967/68 winter were caused by the occurrence of ground ice together with long snow-cover duration. This unfavourable coincidence is well reproduced by our model results, together with eight of the ten reported difficult winters.