| Cloud is an important factor affecting the weather and climate.With equipment such as ground-based observation equipment or satellite remote sensing,information within the cloud can be obtained to study clouds and precipitation.Millimeter-wave radar emits millimeter-level microwave signals,which have the advantage of detecting small particles and can acquire finer cloud structures efficiently.However,using millimeter-wave cloud radar alone to study cloud parameters,due to the impact of precipitation on the attenuation of millimeter-wave radar,the inversion error may be greater.The merging data of millimeter-wave cloud radar,C-band continuous-wave radar and laser-ceilometer can retain the cloud information and reduce the influence of precipitation on the research results and can accurately determine the cloud boundary.The State Key Laboratory of Severe Weather of the Chinese Academy of Meteorological Sciences used a variety of observation equipment to conduct comprehensive observations of clouds and precipitation in Longmen County,Guangdong Province from May to August 2016.The main test of this experiment is that the Chinese Academy of Meteorological Sciences simultaneously deployed several different bands of vertical detection equipment at the same site to jointly observe the characteristics of cloud and precipitation in the South China summer.This article uses the merging data during this experiment to classify clouds into ice clouds,water clouds,and mixed-clouds according to cloud phase classification methods.The cloud top height,cloud base height,cloud thickness,and cloud amount of summer clouds in the Longmen area of Guangdong are preliminary statistical analysis that conducted on the daily changes in the number of clouds and other characteristics,and the macro characteristics of different types of clouds were discussed.The cloud liquid water content of three clouds was inverted,and the distribution characteristics of water content were analyzed.The results are as follows:The frequency of cloud top height,cloud thickness,cloud amount,number of cloud layers,and different heights in the Longmen area has more obvious diurnal variations.The height of cloud tops in the summer of the Longmen area is mainly concentrated at heights below 4 km and heights above 8 km,and the cloud base is mainly distributed below 3 km and above 4 km.After 12 o'clock,the number of high clouds increased significantly,and the height of cloud tops was more than 8 km and the highest was 12 km.The proportion of clouds with thickness less than 2 km is the highest,accounting for more than 30% of the total cloud thickness at that time.The frequency of cloud formation with thicknesses over 6 km is less than 10%,and the daily change of clouds with medium and high thickness is relatively obvious.Clouds in South China are mainly distributed below 12 km height.The frequency of cloud occurrence within a range of 5-6 km is relatively low.There is a high frequency of multi-layer clouds in the afternoon.There is consistency in the frequency of cloud tops and cloud bottoms in the Longmen area.The frequency of cloud top height below 4 km is relatively stable,and the frequency of low clouds gradually increases from 0 o'clock to 10 o'clock.The maximum frequency is close to 40%.The height of the cloud top is up to 15 km,the height of the cloud base is up to 12 km,and the frequency of cloud top and cloud base height below 4-8 km.The frequency of occurrence of mixed-cloud is relatively lowest in summer,and the occurrence frequency of water clouds is relatively stable.The frequency of occurrence of ice clouds in the Longmen area is similar to that of summer clouds.The relative change of LWP in summer water cloud is relatively small,and the change trend of total LWP and mixed cloud LWP is consistent.When the LWP is high,the mixedcloud is the main contribution.The summer average LWP of the mixed-cloud is about 2.5 times that of the water cloud.The average change of echo intensity over the course of the day is roughly divided into 6 stages: 5:00,8:00,14:00,19:00,22:00 and 2:00.At 14 o'clock,the average echo intensity increases to the maximum value during the day,and the average reflectance can reach 20 d BZ at a height of 3-6 km.From 0 to 8 o'clock,the average echo top height is about 12 km,and after 8:00,the echo top height is highest at 15 km.From 8:00 to 14:00,there are several short duration convection processes.In the Longmen area of Guangdong,there are more clouds and precipitation processes in the afternoon and in the middle of the night than in the middle of the night and in the morning.The average maximum reflectivity of the mixed-cloud is the highest,and the frequency of the echo intensity of the mixed-cloud is about 0.7,and the reflectivity at this time is about 10 d BZ.The probability distribution of water clouds is concentrated in the height range of 1-2km,and the echo intensity is-20 d BZ.Meanwhile cloud clouds are mainly composed of cloud droplet particles.The echo center of the ice cloud is at a height of 10 km,and the reflectivity intensity is about-5 d BZ.The total cloud echo intensity center is at 2km and 10 km height. |
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