A triple‐frequency approach to retrieve microphysical snowfall parameters
A triple‐frequency approach to retrieve microphysical snowfall parameters
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DOI：
10.1029/2010jd015430
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发表时间：
2011-06
影响因子：
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通讯作者：
S. Kneifel;M. Kulie;R. Bennartz
中科院分区：
文献类型：
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作者：
S. Kneifel;M. Kulie;R. Bennartz
在三个典型的云雷达频率范围，即Ku波段、Ka波段和W波段，研究了各种雪粒子模式的散射特性和消光特性，包括单个散射特性和平均尺寸分布。研究的模型包括软球体、随机取向的原始非球形颗粒和复杂聚集体，以及水平排列的球体。结果表明，同时使用Ku/Ka波段和Ka/W波段双波长比（DWR）可以实现不同雪粒习性的分离。进一步表明，三频方法对指数大小分布的斜率参数的约束比传统的单DWR方法更严格。当要推导质量相关量时，未知的质量-尺寸关系所带来的不确定性仍然是一个挑战。雪的衰减，特别是在W波段，被发现可能会改变这些结果，尽管是适度的，但不会影响一般结论。对模拟尺寸分布的截止点进行的敏感性研究强调了在未来的散射数据库中包括较大颗粒的潜在好处。
[1] Backscattering and extinction properties of various snow particle models are studied for three typical cloud radar frequency ranges, namely Ku band, Ka band, and W band, both in terms of their individual scattering properties as well as averaged over size distributions. Models studied include soft spheres, randomly oriented pristine nonspherical particles and complex aggregates, as well as horizontally aligned spheroids. It is shown that the concurrent use of Ku/Ka band and Ka/W band dual wavelength ratios (DWR) allows for a separation of different snow particle habits. It is further shown that triple-frequency approaches constrain the slope parameter of exponential size distributions more tightly than conventional single DWR approaches can. Uncertainties introduced by unknown mass-size relations for different snow particle habits remain a challenge when mass-related quantities are to be derived. Attenuation by snow, especially at W band, is found to potentially alter these results, albeit moderately, without affecting the general conclusions. Sensitivity studies performed with respect to cutoffs in the simulated size distribution highlight potential benefits of including larger particles in future scattering databases.