| Based on the millimeter wave radar data and sounding temperature data obtainedfrom the third atmospheric scientific experiment on the Qinghai-Tibet Plateau from July to August 2014,the the phase of cloud hydrometeor in Naqu region of Tibet in summer is inverted by using the fuzzy logic method.The macro-parameter distribution of clouds is obtained by combining with the laser cloud altimeter,and then the micro-parameter distribution is retrieved.The results are as follows:The cloud macro-parameters have the following characteristics:(1)The highestfrequency of cloud bottom height occurs at 1.5 km,followed by 6 km.The maximum height of cloud top is 3 km,followed by 6-9 km.The frequency distribution of clouds with thickness greater than 4 km tends to be stable.As the number of clouds increases,its proportion decreases gradually.(2)The diurnal variation of cloud bottom height on the plateau is small,with only a short increase from 15:00 to 17:00.The cloud top height shows a bimodal distribution.The diurnal variation trend of cloud thickness is consistent with the height of cloud top.(3)The precipitation frequency of convective clouds is lower than that of stratiform clouds,and most of them are in the afternoon.The ice ratio in clouds is not as high as that of stratiform clouds.Stratiform clouds precipitation is less in the afternoon,after midnight,convective clouds over the Plateau transform to stratiform clouds after midnight.Convective clouds develop to the highest level after evening,and the rainfall intensity of convective clouds between 4:00 and 11:00 is higher.The phase in clouds have the following distribution characteristics:(1)Thereflectivity factors of liquid clouds have two distribution centers corresponding to warm clouds and supercooled water layers.The high value centers of reflectivity factors of mixed clouds do not change much with altitude,and the reflectivity of ice clouds above 6km tends to concentrate.(2)The high frequencies of the three phases are concentrated in the 1 km,2-3 km and 3-4 km above the ground respectively.These three types of cloud hydrometeor appeared most frequently in the morning,afternoon and evening,and were lower than other periods in the morning.(3)The thickness of liquid phase clouds is generally less than 0.3 km.The upper limit of the thickness of mixed phase clouds is negatively correlated with the height of cloud bottom.The average thickness of ice phase clouds is the largest when the cloud top is located at 9 km.The thickness of the mixed phase and ice phase in the middle cloud varies slightly.The distribution characteristics of cloud microphysical quantities are as follows:(1)The effective radius and water content of liquid droplets below 2 km increase with height,while the median value effective radius of droplets above 2 km does not change with height.Below 2 km,the effective radius and liquid water content at 11:00 are lower than those at other times.The value is lower in the morning above 2 km.(2)Mean effective radius of ice crystals reaches maximum at 6 km,and the upper limit of the ice water content is at 7 km.Ice crystals are small between 6:00-12:00.After 12:00,there is a maximum area of effective radius and ice water content at 4-9 km over the plateau.(3)The average value of liquid-water path is 30 g/m~2,and that of ice-water path is 9 g/m~2.During the daytime,the fluctuation of liquid-water path is larger than that at night,and the ice-water path shows the characteristics of rising in the afternoon and decreasing after midnight. |
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