我国西北若干种冰、雪及水体反射光谱特性的研究

本文根据1980—1982年在我国西北地区野外实测资料的基础上,详细分析了若干种冰、雪及浑浊水体的反射光谱特性及其与测试目标物的某些参数关系,并根据光谱特性的分类结果提出其最佳遥感波段。     

重盐土在温度变化时的物理化学性质和力学性质

在降温过程中,重盐土的物理化学性质及力学性质发生重要变化:易溶盐向土体冷端迁移;土壤溶液中的硫酸钠呈水合芒硝析出,因而使土体积膨胀(即盐胀);盐胀使土的强度降低。盐胀率随降温速率、上覆荷载值、土的初始密度及土粒间的粘聚力的增大而降低,随土含水量的增大而提高。盐胀率峰值发生在特定的温度区间。在温度回升时,土体积并不明显回缩,这说明盐胀过程具有不可逆性。在温度反复升降过程中,盐胀量逐步累增,土的无侧限抗压强度也逐渐降低。     

STUDY ON SPECTRAL REFLECTION CHARACTERISTICS OF SNOW, ICE AND WATER OF NORTHWEST CHINA

The spectral reflection characteristics of snow, ice and turbid water within spectralrange 380-1200 nm have been analysed. The spectral reflectance of snow decreases withincreasing of snow density and its crystal size, and there is good correlation between densityand spectral reflectance. The spectral reflactance gradually decreases from 95% to 60%within visible range while snow is metamorphosed to glacier ice. The variation of spectralreflectance of turbid water is determined by the silt content of water; that is, when the siltcontent is more than 5400 mgl~(-1) and the wavelengtho f the maximum reflectance is stable(near 820 nm). Based on the test, M_j and C_v, values, the optimum remote sensing bands havebeen selected respectively, namely, 420-450, 840-910, 950-1110 nm for snow, 670-760nm for ice and 730-810 nm for turbid water.