A comparison of ice water content measurement techniques on the FAAM BAe-146 aircraft
A comparison of ice water content measurement techniques on the FAAM BAe-146 aircraft
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FAAM BAe-146 飞机上冰水含量测量技术的比较
DOI：
10.5194/amt-7-3007-2014
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发表时间：
2014
影响因子：
3.8
通讯作者：
A. Vance
中科院分区：
文献类型：
--
作者：
S. Abel;R. Cotton;P. Barrett;A. Vance
抽象的。本文比较了BAE-146型飞机机载大气测量设备(FAAM)上各种测量技术的冰水含量数据。数据来自PIKNMIX现场实验期间测量的一系列云类型，包括混合相层积云、堆积云和卷云。这些测量涵盖了自然界中发现大气冰粒的广泛条件，例如通常在中纬度卷云中发现的低冰水含量环境，以及经常在冷对流云中观察到的冰水含量高得多的环境。这些技术包括使用(I)一个nevzorov热线探头进行大量测量，(Ii)测量的总水分含量(凝结加水汽)与大气中的水蒸气含量之间的差值，以及(Iii)逆流虚拟撞击器(CVI)(仅用于卷云测量)。我们还通过将测量的颗粒尺寸分布(PSD)与冰粒密度如何随尺寸变化的假设进行积分来估计QI。结果表明，唯一能测量高QI值(几个g m−3)的散装冰水含量技术是总水含量减去水汽的方法。对于低冰水含量，我们开发了一种新的nevzorov基线漂移参数，使探测器能够对QI±0.002 g m−3敏感。在卷云中，nv zorov与其他大宗测量结果之间的一致性通常好于2倍的CVI值(qi>；0.008 g m−3)和总含水量减去水汽的方法(qi>；0.02g m−3)。只要对质量-尺寸关系做出适当的先验假设，所有情况下的总体测量结果都可以与PSD的估计值很好地吻合。这在采样的对流云中是有问题的，因为原始冰粒、重环粒子和过冷液滴都存在。在卷云的情况下，我们证明了使用依赖于温度的质量-尺寸关系来匹配体积气的测量是必需的。
Abstract. This paper presents a comparison of ice water content (qi) data from a variety of measurement techniques on the Facility for Airborne Atmospheric Measurements (FAAM) BAe-146 research aircraft. Data are presented from a range of cloud types measured during the PIKNMIX field experiment that include mixed-phase stratocumulus, cumulus congestus and cirrus clouds. These measurements cover a broad range of conditions in which atmospheric ice particles are found in nature, such as the low-ice-water-content environments typically found in midlatitude cirrus and the environments with much higher ice water content often observed in cold convective clouds. The techniques include bulk measurements from (i) a Nevzorov hot-wire probe, (ii) the difference between the measured total water content (condensed plus vapour) and the water vapour content of the atmosphere and (iii) a counterflow virtual impactor (CVI) (only for cirrus measurements). We also estimate the qi from integration of the measured particle size distribution (PSD) with assumptions on how the density of ice particles varies as a function of size. The results show that the only bulk ice water content technique capable of measuring high qi values (several g m−3) was the method of total water content minus water vapour. For low ice water contents we develop a new parametrisation of the Nevzorov baseline drift that enables the probe to be sensitive to qi ± 0.002 g m−3. In cirrus clouds the agreement between the Nevzorov and other bulk measurements was typically better than a factor of 2 for the CVI (qi > 0.008 g m−3) and the method of total water content minus water vapour (qi > 0.02 g m−3). Good agreement with the bulk measurements for all cases could be obtained with the estimate from the PSD provided that appropriate a priori assumptions on the mass–dimension relationship were made. This is problematic in the convective clouds sampled because pristine ice particles, heavily rimed particles and supercooled liquid drops were all present. In a cirrus case, we show that using a temperature-dependent mass–dimension relation was required to match the bulk measurement of qi.