Scales of spatial heterogeneity for perennial and seasonal snow layers
Scales of spatial heterogeneity for perennial and seasonal snow layers
复制标题
常年和季节性雪层的空间异质性尺度
作者：
M. Sturm;C. Benson
摘要雪层的局部观测是积雪性质空间外推和积雪沉积时间记录的基础，但雪层厚度、密度和微观结构的显著横向变化已被充分记录。在这里，我们使用来自阿拉斯加、南极洲和格陵兰岛主要平坦地区的数据，研究了10 - 10万米距离上的层异质性的性质。研究发现，在10 m及以下尺度下，冰川和冰盖上的多年生雪层比季节性雪层更加均匀和横向连续，季节性雪层除了受风和水渗流引入的异质性外，还受当地地形和植被的影响。在100 m左右的尺度上，季节性和多年性雪层的异质性趋于收敛并接近峰值。在更大的尺度（103 - 105米），局地强迫（约100米）继续产生大部分的层非均质性，天气尺度的变化增加了少量的非均质性。在这些更大尺度上的相互关联是基于识别不同的层序列或匹配几个关键的雪层。许多层不能相互关联，因为它们在比雪坑间距更小的尺度（例如100米）上挤压或变化。
Abstract Local observations of snow layers are used as the basis for spatial extrapolation of snow properties and for establishing a time record of snow deposition, yet significant lateral variations in layer thickness, density and microstructure are well documented. Here we examine the nature of layer heterogeneity over distances of 10– 100 000 m using data from primarily flat locations in Alaska, Antarctica and Greenland. We find that at a scale of 10 m or less, perennial snow layers on glaciers and ice sheets are more uniform and laterally continuous than seasonal layers, which, in addition to heterogeneity introduced by wind and water percolation, are also affected by local topography and vegetation. At a scale of about 100 m, heterogeneity of seasonal and perennial snow layers converges and approaches a peak value. At larger scales (103–105m), local (order 100 m) forcing continues to produce most of the layer heterogeneity, with synoptic-scale variations adding small amounts. Cross-correlation at these larger scales is based on recognizing distinctive layer sequences or matching a few key layers of snow. Many layers cannot be correlated because they pinch out or change at scales (i.e. 100 m) smaller than the spacing between snow pits.