The low-frequency conductivity of snow near the melting temperature
The low-frequency conductivity of snow near the melting temperature
复制标题
接近融化温度的雪的低频电导率
DOI：
10.3189/172756401781819193
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发表时间：
2001
影响因子：
2.9
通讯作者：
N. Maeno
中科院分区：
文献类型：
--
作者：
I. Takei;N. Maeno
摘要 雪的介电常数测量是在 –15° 至 0°C 的温度范围和 50 Hz 至 5 MHz 的频率范围内进行的。使用的雪样（密度约 400 kg m-3）是储存的雪（平均粒径：2 mm）和白霜（粒径：<1 至 5 mm）。介电参数的频率特性显示出30kHz附近的介电色散（戴维森-科尔型）和低频介电色散（科尔-科尔圆律型）。交流电电导率在 30 kHz 左右表现出介电色散，并且在高于 1 MHz 和低于 100 Hz 的频率范围内表现出两个特征常数值（高频电导率 σ∞ 和低频电导率 σLOW）。低频电导率 σLOW 在 –2°C 左右出现峰值。以前的研究人员从未注意到这种行为。 σLOW 显示低于 –5°C 时约 1 eV 的活化能。这意味着σLOW 主要是由表面传导引起的。活化能随着温度升高至 –5°C 以上而增加。这意味着该温度范围内的σLOW受到冰表面准液体层的影响。 –2°C 以上的 σLOW 随着温度升高而降低。在融化温度附近明显奇怪的行为归因于多孔雪内的大量自由冰表面。得出这个结论是因为我们在没有自由冰表面的情况下进行的测量表明，对于固体多晶冰样品和在冷却过程中用煤油浸泡的雪样品来说，没有这样的电导率峰值。
Abstract Dielectric measurements of snow were carried out in the temperature range –15° to 0°C and in the frequency range 50 Hz to 5 MHz. The snow samples (about 400 kg m–3 density) used were stored snow (average particle size: 2 mm) and hoar-frost (particle size: <1 to 5 mm). The frequency characteristics of dielectric parameters showed a dielectric dispersion (Davidson-Cole type) around 30 kHz and a low-frequency dielectric dispersion (Cole-Cole circular law type). The a.c. conductivity showed a dielectric dispersion around 30 kHz and two characteristic constant values in the frequency ranges above 1 MHz and below 100 Hz (the high-frequency conductivity σ∞ and the low-frequency conductivity σLOW). The low-frequency conductivity σLOW showed a peak at about –2°C. This behavior has never been noted by previous researchers. The σLOW showed an activation energy of about 1 eV below –5°C. This means that the σLOW is mainly caused by a surface conduction. The activation energy increased with increasing temperature above –5°C. This means that the σLOW in this temperature range is affected by the quasi-liquid layer on ice surfaces. The σLOW above –2°C decreased with increasing temperature. The apparently curious behavior near the melting temperature is attributed to the numerous free ice surfaces within the porous snow. This conclusion was reached because our measurements without the free ice surfaces showed no such conductivity peaks for solid polycrystalline ice samples and for snow samples soaked with kerosene in the cooling process.