| The dynamic and thermal process of cloud and precipitation's generation and development and the micro-physical characteristics are the focuses of Cloud Physics research work.Vertical air velocity in clouds and drop size distribution are the key points of micro-physical parameters that people want to get.The CAMs South China Precipitation Experiment was operated in 2016.Vertically pointing Ka-band Millimeter Radar was used as an effective tool to get the dynamic process and micro-physical characteristics in this experiment.This paper apply Doppler Spectral Density Data in Vertical Air Motions and Drop Size Distribution Retrieval in Cloud and Precipitation according to that.In this study,a stratiform precipitation case in 2016 CAMs South China Precipitation Test is used to retrieve the vertical air velocity in clouds and drop size distribution,and compare the DSD results with Disdrometer and MRR.First,Liquid droplets trace methods is used to get the vertical airspeed which can obtain Doppler spectral in static air.Then we retrieve DSDs from the translated Doppler spectrum by a V-D relation.Last,Normalized Gamma Distribution is used to fit the retrieved DSDs.Several conclusions are got from the case study:1)Weak downwards flow dominates the vertical air motions in cloud between the height from 1km to the 0?level height.The clear-air echo caused by plankton contamination and noisy echo influence the Doppler spectral,as well as the phenomenon of saturation in Z existing near surface layer and affect the results of vertical air motions too.2)Differences in Z is found in the detection of CR?MRR and Disdrometer.MRR's Z data has a smaller difference with Disdrometer than CR.In stable stratiform precipitation,Doppler spectral of CR and MRR are almost consistent.3)In the comparison test of CR and MRR,DSD retrieval results are highly sensitive to the introduction of vertical Airspeed.Because of airspeed changing with height,DSD from CR has an overall increasing number concentration and decreasing value of average radium.DSDs retrieved by the two instruments'spectrum have a similar distribution along all heights,demonstrating the validity of retrieving DSD from Doppler spectral.4)In the comparison of Gamma fitting parameters of CR and disdrometer,the DSD of CR introducing vertical air motions results in has a smaller Dm and a same Nw magnitude comparing to disdrometer.In addition,the base data and Doppler spectral of Ka-band Millimeter Radar in May 6th,2016 are used in the analysis of convective cases like a squall line.Also,data of SA Radar in Guangzhou,China was also utilized as a comparison for the detection of MRR.The whole passing process of the squall line case was got by SA's volume scan and CR's time-heights pictures.The main conclusions are as follows:1)In the convective area of the squall line during the time of 18:00-18:30,the Z?Zdr?Kdp get by SA imply the existence of intensive rain and large-scale raindrops.In the convective and stratiform area of the squall line,ice crystals or melting hailstone may exist around the height of 0°level.2)In the vertical air velocity in clouds and drop size distribution results of CR,when the convection is passing by,fierce updrafts can reach the magnitude of 4-5m/s.Updrafts gets weaker when the convection translates to stratiform area.The obvious updraft at 16:04 could trigger the convection at 16:50.Raindrops below the 0°level are between 1-4mm.Raindrops are getting larger with the falling process.3)Comparing the error of reflectivity between SA and CR in the measurement of Z.The echo area is different between the two radars and echo absence exist in the convection part.In the quantitative comparison,Z of SA and CR are around 12-24dBZ,8-10km,and SA has a bigger data overall,which is also more concentrated as well.SA has a bigger Z value at every height,the difference is decreasing with height.The deviation is about3.45 in 8.41km and 1.75 in 10.66km.At 3km,the value and change tendency of Dm are alike between SA and CR,which are around 0.8-2.0mm. |
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