Application Of Cloudsat In The Study Of Precipitation Clouds

Artificially inducing precipitation is one of the ways to alleviate the shortage of water resources by developing and utilizing air water. Meanwhile, for atmospheric environmental disaster, such as severely haze which is harmful for human health and city extreme high temperature which caused by urban heat island, artificially inducing precipitation is the effective intervention measure in these critical situations as well. In order to carry out artificial water operation scientifically and reduce the manpower investment blindness, employing the CloudSat satellite data, the vertical distributions of cloud microphysical properties of the potential clouds for artificially inducing precipitation including stratus and stratocumulus were studied firstly. Then the vertical distributions of microphysical properties of heavy precipitation clouds were revealed through analyzing the clouds in the episodes of heavy snowfall and rain in northern Xinjiang, and the relationship between cloud microphysical properties and rainfall precipitation was discussed. Eventually, the similarities and differences between rainfall cloud and snow cloud were analyzed comparatively.The study will provide new scientific observations and theoretical basis in designing schemes for artificially inducing precipitation and forecasting heavy precipitation. The results are as follows.The stratus appeared more than stratocumulus and the ice clouds and liquid clouds in stratus distributed in1.0-11.0km and0-9.0km altitudes respectively, while ice clouds and liquid clouds in stratocumulus distributed in0-9.0km altitudes. Cloud particle effective radius, number concentration and water content were greater in stratocumulus than in stratus, so that stratocumulus is a better artificial precipitation object for this reason. The stratus and stratocumulus frequently appeared in spring, summer and autumn, but were seldom seen in winter and particularly stratocumulus was even less. Cloud particle effective radius, number concentration and liquid water content in stratus were greater in summer than other seasons.Deep convective clouds and stratiform clouds are the main cloud types in snowfall processes. Ice effective radius (IER) emerged obvious stratification in the vertical height, and the lower the cloud layer, the higher the IER value. Particles (IER<50μm) distributed throughout the clouds and more in the upper area and particles(IER≥100μm) distributed in2.0-5.0km, and particles (50μm≤IER<100μm) were48.8-74.9%. Ice number concentration increased rapidly with the increase of height in the lower part of the clouds and then stabilized after reaching a certain height. Generally, particles with ice number concentration less than50L-1only appeared at the bottom of the clouds, and the high values appeared mainly in the upper clouds. Ice water content showed a single peak distribution in vertical height and high IWC particles appeared at4.0-6.0km height layer. Deep convective clouds, along with cumulus and stratiform clouds are the main cloud types in the heavy rainfall process. Ice clouds and water clouds distributed in2.0-11.0km. Ice effective radius (IER) emerged obvious stratification in the vertical height, and the lower the cloud layer, the greater the IER value. Particles (IER>150μm) distributed at the2.0-4.0km layer and85.6%of particles (100μm<IER≤150μm) distributed in2.0-6.0km. Water clouds distributed below6km. Those with IER less than50μm, accounted for26.9%, distributed throughout the cloud and the percentages increased with the increase of height. The greater value of liquid effective radius (LER) distributed in the middle of the clouds layer and the maximum appears3.0km, and the top and bottom of the clouds were filled with low LER ice particles. Particles with IER less than5um, accounted for71.2%, distributed throughout the cloud and mainly spread at3.0-4.0km layer. Particles with IER greater than20um, only accounted for1.3%, concentrated distribution within2.0-4.0km height layer. Ice number concentration showed an increasing trend with the increasing of height. Liquid number concentration (LNC) emerged obvious stratification in the vertical height, and the lower the cloud layer, the greater the LNC value. Particles with LNC less than20cm-3accounted for25.3%, and the distribution in the vertical height increased with increasing height. Those with LNC greater than60cm-3were12.3%and distributed in2.0-5.0km.Ice water content(IWC) showed Gaussian distribution in vertical height and high IWC appeared at6.0-7.0km layer. IWC and ice water path of clouds in raining areas were larger than those in the areas of non-precipitation areas. Liquid water content (LWC) showed a decreasing trend with the increase of height, and particles with LWC greater than500.0mg/m3accounted for12.3%, distributed in2.0-3.0km.The vertical distributions of rainfall and snow cloud microphysical properties are slightly different. Overall, ice effective radius showed a decreasing trend with the increase of height. Ice effective radius in the snow clouds had a greater variation than in the rain clouds in the lower part of clouds. Ice number concentration increased rapidly with the increase of height in the lower layer. However, after reaching a certain height, the growth trend slowed down and ice number concentration in the snow clouds slightly decreased at the top of the clouds. Ice water content showed both unimodal and bimodal distribution in the vertical height. The rainfall clouds were mainly unimodal, but the snowfall clouds had both, and the peak value distributed in the middle to lower part of clouds.