Hydrometeor Shape Variability in Snowfall as Retrieved from Polarimetric Radar Measurements
Hydrometeor Shape Variability in Snowfall as Retrieved from Polarimetric Radar Measurements
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从偏振雷达测量中检索降雪中的水凝物形状变化
DOI：
10.1175/jamc-d-20-0052.1
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发表时间：
2020
影响因子：
3
通讯作者：
de Boer, Gijs
中科院分区：
文献类型：
--
作者：
Matrosov, Sergey Y.;Ryzhkov, Alexander V.;Maahn, Maximilian;de Boer, Gijs
一种基于极化雷达的大气冰粒子形状反演方法被应用于部署在阿拉斯加州奥利克托克角（70.495°N，149.883°W）的扫描Ka波段雷达的降雪测量。的平均长宽比，这是定义的水凝物的小到大尺寸比的球状颗粒模型，检索作为颗粒形状参数。雷达参数包括反射率、微分反射率和共极相关系数。反演结果表明，平均长宽比低于0.2-0.3的水凝物通常出现在气温高于−17° C至−15°C的地区，这与已被证明有利于平面习性的原始冰晶生长的制度相对应。对应最低平均纵横比的雷达反射率通常在−10和10 dBZ之间。对于较冷的温度，平均纵横比通常在0.3和0.8之间的范围内。水凝物的长宽比随着粒子从温度范围为-17 ° C至-15 °C的高度向地面过渡而有增加的趋势。这种增加被认为是由聚集和成霜过程引起的，该过程导致颗粒变得更加球形，并且与显示出差异反射率随着反射率增加而降低的区域相关联。在最低海拔的长宽比检索是一致的，在现场测量使用基于表面的多角度雪花相机。在主要水凝物种类发生变化的高度上观测到粒子纵横比剖面的明显梯度，这是通过垂直指向的多普勒雷达的光谱测量推断的。
A polarimetric radar–based method for retrieving atmospheric ice particle shapes is applied to snowfall measurements by a scanning Ka-band radar deployed at Oliktok Point, Alaska (70.495°N, 149.883°W). The mean aspect ratio, which is defined by the hydrometeor minor-to-major dimension ratio for a spheroidal particle model, is retrieved as a particle shape parameter. The radar variables used for aspect ratio profile retrievals include reflectivity, differential reflectivity, and the copolar correlation coefficient. The retrievals indicate that hydrometeors with mean aspect ratios below 0.2–0.3 are usually present in regions with air temperatures warmer than approximately from −17° to −15°C, corresponding to a regime that has been shown to be favorable for growth of pristine ice crystals of planar habits. Radar reflectivities corresponding to the lowest mean aspect ratios are generally between −10 and 10 dBZ. For colder temperatures, mean aspect ratios are typically in a range between 0.3 and 0.8. There is a tendency for hydrometeor aspect ratios to increase as particles transition from altitudes in the temperature range from −17° to −15°C toward the ground. This increase is believed to result from aggregation and riming processes that cause particles to become more spherical and is associated with areas demonstrating differential reflectivity decreases with increasing reflectivity. Aspect ratio retrievals at the lowest altitudes are consistent with in situ measurements obtained using a surface-based multiangle snowflake camera. Pronounced gradients in particle aspect ratio profiles are observed at altitudes at which there is a change in the dominant hydrometeor species, as inferred by spectral measurements from a vertically pointing Doppler radar.
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DOI：
--
发表时间：
2018
期刊：
影响因子：
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作者：
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DOI：
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2008
期刊：
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影响因子：
2.2
作者：
V. Melnikov
通讯作者：
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液云微物理过程可以用于垂直指向云雷达校准吗？
影响因子：
3.8
作者：
M. Maahn;F. Hoffmann;M. Shupe;G. de Boer;S. Matrosov;E. Luke
通讯作者：
E. Luke
DOI：
--
发表时间：
1991
期刊：
影响因子：
--
作者：
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S. Matrosov