Shattering and particle interarrival times measured by optical array probes in ice clouds
Shattering and particle interarrival times measured by optical array probes in ice clouds
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DOI：
10.1175/jtech1922.1
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发表时间：
2006-10-01
影响因子：
2.2
通讯作者：
Bansemer, A.
中科院分区：
文献类型：
--
作者：
Field, P. R.;Heymsfield, A. J.;Bansemer, A.
光学阵列探测器是确定云微物理结构的重要工具之一。一段时间以来，人们已经知道，这些探头外壳上冰晶的破碎可能导致粒度分布的不正确测量，如果所得的假颗粒不被拒绝，则随后导出的微物理性质。在本文中，它表明，这些探针测量的粒子的到达时间间隔可以是双峰的“云”探针比“降水”探针更受影响。长的到达间隔时间模式代表真实的云结构，而短的到达间隔时间模式是由破碎的冰粒碎片造成的。对于这里考虑的飞行，如果在四种情况中的三种情况下使用2 x 10（-4）s的到达间隔时间阈值过滤碎片颗粒，在另一种情况下使用1 x 10（-5）s的到达间隔时间阈值过滤碎片颗粒，则在存在大颗粒的情况下，测量的总浓度可能受到高达4倍的影响，如通过超过1 mm的质量加权平均尺寸确定的，或指数斜率参数落在30 cm（-1）以下。当粒径分布较窄（质量加权平均粒径< 1 mm）时，对本文所述的情况，冰水含量可高估20%-30%。
Optical array probes are one of the most important tools for determining the microphysical structure of clouds. It has been known for some time that the shattering of ice crystals on the housing of these probes can lead to incorrect measurements of particle size distributions and subsequently derived microphysical properties if the resulting spurious particles are not rejected. In this paper it is shown that the interarrival times of particles measured by these probes can be bimodal-the "cloud" probes are more affected than the "precipitation" probes. The long interarrival time mode represents real cloud structure while the short interarrival time mode results from fragments of shattered ice particles. It is demonstrated for the flights considered here that if the fragmented particles are filtered using an interarrival time threshold of 2 x 10(-4) s in three of the four cases and 1 x 10(-5) s in the other, then the measured total concentration can be affected by up to a factor of 4 in situations where large particles are present as determined by the mass-weighted mean size exceeding 1 mm, or the exponential slope parameter falling below 30 cm(-1). When the size distribution is narrow (mass weighted mean size < 1 mm), ice water contents can be overestimated by 20%-30% for the cases presented here.