| Clouds play an important role in the climate system through their profound effects on the radiative energy budget,energy balance and water cycles.The study of clouds macroscopic and microscopic characteristics which is very important for in-depth understanding of the role of clouds in climate change,improve the parameterization of clouds process in model and weather modification.The macrophysical properties of clouds above the Huainan area and the distribution and seasonal variations of clouds microphysical properties are analyzed based on the cloud radar and microwave radiometer dataset from March 1,2015 to February 28,2016.A preliminary analysis on the macro and micro structure characteristics of light precipitation clouds and snow clouds,the vertical structure evolution and water content,effective particle radius variation characteristics of cloud before and after precipitation for a light precipitation case and a snow case were conducted.The results show that:(1)The occurrence of cloud base peaks at both 2.5 and 7.0 km while the cloud top peaks at 2.5 and 8.5 km.About 80.2%of the cloud thickness is within 2 km.The diurnal cycles of cloud base and top are significant in spring and autumn.In spring and autumn,both the cloud base and top heights decrease after sunrise and then increase from mid-afternoon to midnight,the cloud thickness is higher at night.The occurrence of high,middle and low clouds is 57.8%,32.9,8.8%,respectively.The average thickness of middle cloud is the largest,which is 1.5 km,the low cloud thickness is 1.0 km,and the high cloud thickness is the smallest,which is 0.9 km.Clouds can also be classified based on the number of cloud layers.Single-layer clouds account for the largest proportion in multi-layer clouds system.As the number of cloud layers increases,the frequency of occurrence of clouds at two or more layers gradually decreases,and multi-layer clouds occur frequently in summer and autumn.(2)Single peak is shown in the probability distribution function(PDF)of the ice and liquid water content,effective radius of ice cloud and liquid cloud.The ice water content is less than 0.35 g/m~3,with 92.96%of the values distribution in the summer between 0~0.2 g/m~3,and around 90%of the values distribution under 0.1 g/m~3in spring,autumn and winter.Liquid water content is between 0.1~0.7 g/m~3 with maximum frequencies around 0.25~0.3 g/m~3 in spring,autumn and winter and0.35~0.4 g/m~3in summer,respectively.The ice effective radius is between 40~75?m,with 79.15%of the values between 55~65?m in summer,and 70%of the values around 50~60?m.The liquid effective radius is less than 7?m,with most frequent values around 4.0~5.0?m.From the vertical distribution,the mean value of summer ice water content at different heights is much greater than the other three seasons.The vertical distribution shows increasing ice water content with height,the maximum ice water content occurs near the height of 6.5~8.0 km and the largest ice water content is0.133 g/m~3 in summer.The mean value of summer ice effective radius at different heights is much greater than the other three seasons.In the spring,summer,autumn and winter,the ice effective radius increased with height,reaching a maximum at 6.27km,11.76 km,7.5 km,and 6.69 km,respectively.The maximum values corresponded to 53.1?m,60.7?m,55.71?m and 52.56?m,respectively.The largest ice water content is 60.7?m in summer.There is no significant difference in the vertical variation of liquid effective radius in the four seasons.The liquid effective radius increased with height,reaching a maximum around 1.7~2.0 km.The maximum values corresponded to 4.9?m.(3)With high spatial-temporal resolution,the millimeter wave cloud radar is good at observing details of lighter rain cloud system,providing good support for the development of cloud prediction and cloud research of macro and micro physics properties.Mixed cloud existed has echo intensity,Doppler velocity and velocity spectrum width three bright bands.The velocity spectrum bright band with a height less than Doppler velocity bright band,and Doppler velocity bright band with a height less than echo intensity bright band.Mixed cloud existed“Snow-Supply”vertical structure in this process.There were certain supercooled water in mixed cloud,and the vertical distribution of supercooled water was not continuous,and the distribution of the range was relatively wide.In the stratus cloud stage,as the precipitation system approaches,the effective radius of the particles increases and the water content in the cloud gradually increases.Before the stratus cloud rainfall,the particle radius and liquid water content in the cloud reached 13.5-285.2?m and 0.22-0.57 g/m~3,respectively,and reached the maximum in the cloud during the precipitation process.Because precipitation takes away a large amount of water vapor,the water content of the cloud layer decreases sharply after precipitation,and the particles also become smaller.The effective radius of the inverted particles is 6.94-95.73?m,and the liquid water content is 0.096-0.646 g/m~3.Both the amount of water and the effective radius of the particles are greater than after precipitation.(4)Analysis of snowfall clouds shows that:the millimeter wave cloud radar is good at observing details of snow cloud system and obtain information about clouds macro and micro physics properties.The maximum radar reflectivity cloud represent the max water content area in the snow cloud.Echo intensity gradually increases and have several peaks in the reflectivity profile with decreasing height due to different wind speed at different wind speeds at different heights.The snow water content was less than 0.03 g/m~3 at the early stage of snowfall and the dissipation phase of the snowfall system.In thriving snow clouds,the snow water content was between0.001~0.104 g/m~3.The snowfall inversion results showed that the snowfall was the largest at 00:00 on the 21st,which was 0.89 mm/h.These data can provide information for the development of cloud model and snow seeding potential evaluation. |
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