Studies Of Cloud Microphysical Properties Based On Ka-band Millimerter Wave Cloud Radar

The macro-microscopic physical characteristics and dynamic characteristics of the cloud have great significance to weather forecasting,climate prediction,and flight safety.In recent years,millimeter-wave radars have become one of the main devices for cloud observation.The paper uses the fundamental data and spectral data of millimeter-wave radar to study the microphysical properties of the cloud and retrieval of air vertical speed in cloud.The main contents and conclusions include:(1)By analyzing the observation data(reflectivity,mean Doppler velocity,linear depolarization ratio and spectral width)and ECMWF reanalysis data(temperature)of the HMBQ millimeter-wave radar of Beijing YanQing,the fuzzy logic algorithm of cloud particle phase inversion is established,and by using the asymmetric T-type functions.The results show,by analyzing the parameters of cloud radar detection by fuzzy logic method,the phase state of water condensate can be identified effectively,reflecting the evolution process.Compared with Wang's algorithm,this algorithm considers spectral width,which is an important parameter to identify the mixed phase,making the recognition result more reasonable.(2)A peak-identification algorithm based on the Doppler velocity spectra of MMCR was designed.Following the application of the algorithm,the polynomial was fit to the local spectrum by the least-squares method,obtaining the spectral distribution of different types of particles.Finally,the LWC in the cloud was derived by different types of reflectivity values,and compared with observations by MWR.The results show,in the mixed-phase clouds,the spectral moment parameters of the total spectral reflect the characteristics of the snowflakes and the supercooled liquid were ignored.Therefore,the LWC deduced by the total reflectivity could be underestimated.However,the bimodal characteristics of the Doppler spectra can be used to identify and quantify the supercooled liquid in cloud.However,using the bimodal characteristic of the Doppler spectra,the supercooled liquid can be effectively identified and quantified,and the LWP of supercooled liquid by Doppler spectra are consistent with the LWP of MWR.(3)The accuracy of the three radar noise-level compute method are assessed by using simulated data and spectra processing technologies are researched.A retrievalmethod of air vertical speed was studied using MMCR Doppler spectral data.And the influence of noise level error on the air vertical speed is evaluated quantitatively.The results show,the noise error of the three methods are relatively small when the spectral width and signal noise are small;But when the spectral width and signal noise are relatively large,the segment method is the most accurate and stable method,the objective method is overrated which can cause the air vertical velocity of inversion to be small.The air vertical velocity of inversion is analyzed by combining the reflectivity,mean Doppler velocity and spectral width,which indicates that the results are relatively reasonable.