Study Of Microphysical Properties In Aircraft Icing Environment In Hohhot Area

It is important to carry out the research on the characteristics of aircraft ice accumulation environment and the spatial and temporal distribution of supercooled water to ensure flight safety,provide a basis for test flights,develop cloud water resources,and prevent and mitigate disasters.In this thesis we analyzed the macroscopic characteristics of weather situation,water vapor conditions and cloud system conditions in seven aircraft ice-accumulation environments in Hohhot area using airborne sounding data,ERA5 reanalysis data,Fengyun-2satellite data and GPM precipitation satellite data,revealed the horizontal and vertical microphysical structure characteristics of cloud particles,and fitted the particle spectrum distribution parameters.The specific results obtained in the thesis are as follows:The weather situation of the aircraft ice accumulation environment in the Hohhot area is mainly classified into:low pressure ridge type,low pressure type,and sub-high type.The humidity field characteristics show that the water vapor in the detection area is mainly co-existing with radiation and dispersion,and the water vapor flux dispersion is generally-0.8×10^-5Kg h Pa^-1m^-2s^-1.The cloud tops are mainly classified as cirrus and cirrus clouds,and the temperature of the cloud tops is mainly around 240 k.Precipitation did not occur once during the aircraft detection period,and occurred in the remaining six times.The vertical characteristics revealed by the airborne particle probe are:the cloud system is mostly two-layered,and the inverse thermosphere appears in four of the seven detections,and the height of the inverse thermosphere is mainly about 5600 m.The particle number concentration and liquid water content of CIP and PIP are higher at the inverse thermosphere height,which is conducive to the generation of cumulus ice.The maximum values of liquid water content and particle number concentration of precipitation clouds and non-precipitation clouds do not vary much;the maximum values of liquid water content and effective diameter of CIP are significantly lower than those of precipitation clouds;the maximum values of particle number concentration of PIP are also significantly lower than those of precipitation clouds;whether it is precipitation clouds or non-precipitation clouds,the spectrum of CDP particle spectrum can reach 45μm.The width of CDP particle spectrum can reach 45μm in both precipitation and non-precipitation cloud systems,and all of them are multi-peak distribution,with peaks occurring consistently in the range of 10～25μm.The width of CIP and PIP spectrum in non-precipitation cloud systems is narrower than that in precipitation cloud systems.The characteristics of microphysical levels around 5000 m are as follows:（1）The maximum values of 7 times CDP particle number concentration are generally around 100～400 cm^-3.The maximum value of liquid water content is significantly higher in summer than in other seasons.Effective diameter effective diameter mean value is higher in autumn season and lower in summer;almost all levels detect effective diameter maximum up to 49μm.（2）The mean value of CIP number concentration is fairly distributed,and there is no obvious pattern in the distribution of number concentration maximum.The average value of liquid water content with precipitation is significantly higher than that without precipitation.The mean and maximum values of effective diameter are relatively large in all three seasons.（3）The average value of PIP number concentration,the number concentration in spring and autumn is higher than that in summer.Liquid water content flat mean value is generally higher in autumn;liquid water content maximum value is higher in summer.The average value of effective diameter is higher in autumn,and the maximum value of effective diameter can reach 3000～4000μm for almost all horizontal detections（4）The spectral width of CDP particle spectrum of non-precipitation cloud system is 30μm,and the particle spectrum of precipitation cloud system can reach 40μm except for the detection of 20μm at 15:00 on July25,2020,and the particle spectrum of precipitation cloud system is single-peaked distribution,and the particle spectrum of non-precipitation cloud system is single-peaked and The particle spectra of the non-precipitation cloud system are single-peaked,and the particle spectra of the non-precipitation cloud system are both single-peaked and double-peaked;the peak of the particle spectra of the double-peaked distribution is 10～20μm,and the peak of the particle spectra of the single-peaked distribution is 10μm.Finally,the mean particle spectra of the particle number concentrations detected by CDP were analyzed and fitted with the gamma function and K-M function.The mean particle spectra of CDP showed that the mean particle of ten horizontal detections mostly showed bimodal and single-peaked types,and there were very few multi-peaked types;in the process of fitting the mean particle spectra of CDP with the gamma function,the shape factor was up to 102.59,which was two orders of magnitude higher than the lowest The correlation coefficients of the Gamma distribution for the third and tenth fits were 2.23 and 2.77,respectively,and the correlation coefficients of the fits were 0.53 and 0.51,respectively,and the correlation coefficients of the K-M distribution fits were 0.50 and 0.43,respectively,which were relatively similar,but the correlation coefficients of the rest of the Gamma function fits were almost all above 0.7 while the K-M function fit correlation coefficients are almost all above 0.5 under,indicating that the Gamma function fit correlation coefficients are significantly higher than the K-M function fit.