Temporal and spatial variations in spectral reflectance and characteristics of surface dust on Gulkana Glacier, Alaska Range
Temporal and spatial variations in spectral reflectance and characteristics of surface dust on Gulkana Glacier, Alaska Range
复制标题
DOI：
10.3189/002214309789470914
复制
发表时间：
2009
影响因子：
3.4
通讯作者：
N. Takeuchi
中科院分区：
文献类型：
--
作者：
N. Takeuchi
摘要2001年5月至9月，在美国阿拉斯加州阿拉斯加山脉的Gulkana冰川表面，在6个不同的海拔高度测量了可见光到近红外波长范围（350-1050 nm）的光谱反射率。测量结果显示，冰川表面的光谱反射率是可变的，光谱随时间和海拔高度而变化。5月的光谱是一个典型的湿雪表面：反射率范围约为0.4至0.8，一般随波长的增加而减少。随着融雪的进行，反射率逐渐下降，在400-600和670-680 nm波长范围内出现了特定的反射，对应于雪藻水华导致的红色雪面。当冰表面暴露时，光谱最终移动到较低（0.1-0.4）和平坦的反射率曲线，这是被灰尘污染的冰表面的典型特征。对冰川表面尘埃的分析表明，其数量和特征在空间和季节上都有变化，并与光谱相关。结果表明，该冰川光谱反射率的时空变化不仅与冰川表面的物理性质有关，还与冰川表面的生物物质（如红色雪藻细胞和冰尘）有关。
Abstract Spectral reflectances in the visible to near-infrared wavelength range (350–1050 nm) were measured on the surface of Gulkana Glacier, Alaska Range, Alaska, USA, at six different elevations from May to September 2001. The measurements showed variable spectral reflectances on the glacier surface, and the spectra changed over time and elevation. The spectra in May were those of a typical wet snow surface: the reflectance ranged approximately from 0.4 to 0.8, and generally decreased as the wavelength increased. As snowmelt proceeded, the reflectance gradually fell, and specific absorptions appeared in the spectrum at wavelength ranges of 400–600 and 670–680 nm, corresponding to a red snow surface due to snow algal bloom. As the ice surface was exposed, the spectrum finally shifted to a lower (0.1–0.4) and flat reflectance curve, typical of an ice surface contaminated with dust. Analyses of the dust on the glacier surface showed that its quantity and characteristics changed spatially and seasonally and were correlated with spectral albedo. The results showed that the temporal and spatial variations in spectral reflectance on this glacier are due not only to physical properties of the glacier surface, but also to biogenic materials on the surface (e.g red-colored snow algal cells and cryoconite).