关键词: 南方冬季湿雪, 光谱测量, 光谱分析, 光谱特征

Abstract: In China, the study of spectral characteristics of snow is more concentrated in northern areas, while the study of wet snow in southern areas is relatively rare. In this paper, the Fieldspec4 portable spectrometer was used to collect spectrum data of winter wet snow in Nanjing City, and the influences of solar elevation angle, slope, aspect, underlying surface and mixed snow and vegetation on snow reflectance were analyzed. The result indicates that snow reflectance changes smoothly in visible band and decreases rapidly in near-infrared region. There are absorption regions of snow reflectance near 1 020 nm, 1 250 nm. In the state of wet snow, snow reflectance decreases as the solar elevation angle increases. While the moisture content has much more influence on snow reflectance than the solar elevation angle in the state of water wet snow. Snow reflectance of sunny slope rises significantly with the increase of slope, and it is far higher than that in shady side. The difference of several underlying surfaces has limited influence on snow reflectance when the snow depth reaches a certain value, otherwise it will have a significant impact. Pure snow reflectance is the highest in visible band, and in near-infrared band snow reflectance from mixed snow and vegetation is the highest. Before the curves intersect, snow reflectance from mixed snow and vegetation increases gradually when the snow coverage rate on the vegetation increases. With the intersection moves forward, the reflectance comes closer to the pure snow reflectance. In addition, snow reflectance from snow under forst is the lowest. The measurement and analysis of winter wet snow reflectance in Nanjing City are of great significance for acquainting spectral characteristics and variation regularity, as well as snow quantitative remote sensing and its parameters inversion.

Key words: winter wet snow in southern China, spectral measurement, spectral analysis, spectral characteristics