机载热线含水量仪探测数据校验方法

机载含水量仪是目前云中液态水含量唯一的探测仪器,其准确性直接影响人工增雨作业条件判别。基于2015年和2017年四川盆地南部开展的10架次飞机云物理探测试验,考察机载热线含水量仪LWC-100探测数据发现存在异常极大值、负值数量多等问题。通过分析DMT（Droplet Measurement Technologies）公司云粒子探头（cloud droplet probe,CDP）、云粒子图像探头（cloud imaging probe,CIP）、降水粒子图像探头（precipitation imaging probe,PIP）数据,提出对入云前的干功率进行重新计算的3种方法:方法1以CDP探头的不同粒子尺度分档为标准,不低于某一档尺度的粒子数浓度大于0记为入云；方法2以CDP的数浓度大于10 cm-3为入云判定条件；方法3以CDP,CIP,PIP 3种探头探测的粒子数浓度同时大于0记为入云。结果显示:3种方法均有效纠正液态水含量不为0的情况,负值数量也较探测数据明显减少。方法1以不小于5 μm的粒子数浓度大于0记为入云,校验计算得到的液态水含量以负值数量和大小作为评价依据较方法2和方法3更优。

Calibration for Data Observed by Airborne Hot-wire Liquid Water Content Sensor

Based on the cloud microphysical detection data of 10-sortie aircraft over southern Sichuan Basin in 2015 and 2017, the liquid water content measured by DMT (Droplet Measurement Technologies) hot-wire liquid water content sensor is examined, and abnormal values in maximum, minimum and negative values are found.There are 4 possible causes for the abnormal maximum, minimum and negative values of liquid water content. First, the errors are caused by multiple parameters such as temperature, air pressure and vacuum velocity, which may lead to the error superposition of calculated values. Second, the on-board operators didn't calibrate the zero before entering the cloud. Third, the on-board operators only calibrate the zero once before entering the cloud during the whole flight. Fourth, the interval between cloud entry and exit is too short, so that the manual zero calibration is inaccurate.Using cloud particle spectrum data from cloud droplet probe (CDP), cloud imaging probe (CIP) and precipitation imaging probe (PIP), three solutions are proposed for calibrating hot-wire liquid water content sensor. Solution 1 is to set the criteria for entering cloud as the concentration of particle above a certain size from CDP probe greater than 0. Solution 2 is to set the criteria for entering cloud as the number concentration of cloud particles greater than 10 cm-3 from CDP probe. Solution 3 is to set the criteria for entering cloud as the number concentration from CDP, CIP and PIP probe greater than 0. The results show that when the number concentration is 0 from CDP, CIP and PIP probe, the original non-zero liquid water content problems are corrected by these solutions.To avoid the influence of ice phase particles on CDP number concentration, the verification is carried out in the positive temperature zone. All the test results show that the negative proportion of liquid water content is also significantly reduced compared with the original data. Solution 1 reduces the negative proportion of liquid water content, and make the minimum and maximum more reasonable than other scales. The liquid water content measured by Solution 1 are more reasonable than Solution 2 and 3.