基于飞机探测的陕西及周边地区结冰云层微物理特征分析

Analysis of microphysical characteristics of icing clouds in Shaanxi and surrounding areas based on aircraft probing

2021年,在陕西及周边地区利用国王350飞机开展了21次自然结冰资源探测试验,通过对CCP机载探测数据的研究,分析了结冰云层的微物理特征,并对运输类飞机适航标准CCAR-25部附录C包线的符合性进行了评估。结果表明:2021年自然结冰资源探测试验期间,在结冰云层内部,90%的液态水含量(liquid water content,LWC)小于0.15 g/m^(3),约一半的结冰遭遇样本LWC低于0.07 g/m^(3);中值体积直径(median volume diameter,MVD)约85%的样本落在10~25µm范围内,LWC大于0.2 g/m^(3)的样本主要出现在MVD为18~22µm之间;环境温度(outside air temperature,OAT)最常出现在-6~-4℃范围内,占结冰总暴露距离的47%。同时,在-10~0℃范围内的结冰遭遇样本中,97.3%的样本附录C包线符合性低于40%,在-20~-10℃范围内的结冰遭遇样本中,91.7%的样本附录C包线符合性低于40%。虽然陕西及周边地区具备一定条件的结冰气象环境,可满足试验机在结冰云层内进行盘旋飞行,以保证获得足够的结冰飞行时间或结冰厚度,但与CCAR-25部附录C规定的连续最大结冰包线还有差距。如果要覆盖全年的结冰气象条件,则CCAR-25部附录C温度与海拔高度的包线还需要考虑夏季、秋季的数据做进一步优化。

In 2021,a series of 21 natural icing resource probing tests were conducted in the Shaanxi region and its adjacent areas using the King 350 aircraft.Through meticulous analysis of onboard Cloud Combination Probe(CCP)detection data,the intricate microphysical characteristics of icing cloud layers were meticulously investigated.Moreover,an in-depth evaluation of compliance with the airworthiness standard,CCAR-25 Appendix C envelope for transport aircraft,was undertaken.The findings reveal that throughout the course of the 2021 natural icing resource exploration tests,within the confines of the icing cloud layers,the liquid water content(LWC)remained below 0.15 g/m3 for 90%of instances.Notably,nearly half of the observed icing encounters exhibited an LWC below 0.07 g/m^(3).Median volume diameter(MVD)data illustrated that approximately 85%of samples fell within the 10 to 25µm range,whereas instances of LWC surpassing 0.2 g/m^(3) were predominantly noted within the MVD values of 18 to 22µm.Furthermore,the outside air temperature(OAT)typically ranged between-6 to-4℃,accounting for nearly half(47%)of the total icing exposure duration.Furthermore,the comprehensive analysis of icing encounters in the temperature range of-10 to 0℃ demonstrated a notable compliance rate below 40% for 97.3% of the samples,based on the criteria outlined in Appendix C.Similarly,within the-20 to-10℃ range,91.7% of the samples illustrated a compliance rate below 40%for Appendix C envelope.While the Shaanxi region and its neighboring environs offer conducive icing meteorological conditions suitable for executing hovering flight within icing cloud layers to satisfy stipulated icing flight duration or thickness requirements,a discernible discrepancy remains when compared to the continuous maximum icing envelope mandated by CCAR-25 Appendix C.To comprehensively encompass year-round icing meteorological conditions,including those during summer and autumn,a further refinement of CCAR-25 Appendix C's envelope with respect to temperature and altitude parameters is strongly advocated.This study not only provides intricate insights into the microphysical nuances of icing cloud layers but also emphasizes the imperative for augmenting the representation of these complexities within airworthiness regulations and aviation safety protocols.